Ublox EVA-8M Series Quick setup guide

EVA-8M and EVA-M8 series
u-blox 8 / u-blox M8 GNSS SiP modules
Hardware Integration Manual

Abstract
This document describes the hardware features and specifications of u-blox EVA-8M and EVA-
M8
series GNSS modules. The EVA series modules boast the industry’s smallest form factor and are a
fully tested standalone solution that requires no host integration. The EVA-8M and EVA-M8
series
modules combine excellent GNSS performance with highly flexible power, design, and serial
communication options.
www.u-blox.com
UBX-16010593 - R06


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Document Information
Title EVA-8M and EVA-M8 series
Subtitle u-blox 8 / u-blox M8 GNSS SiP modules
Document type Hardware Integration Manual
Document number UBX-16010593
Revision and date R06 7-Feb-2019
Document status Early Production Information
Product status Corresponding content status
In Development /
Prototype
Objective Specification Target values. Revised and supplementary data will be published later.
Engineering Sample Advance Information Data based on early testing. Revised and supplementary data will be published later.
Initial Production Early Production Information Data from product verification. Revised and supplementary data may be published later.
Mass Production /
End of Life
Production Information Document contains the final product specification.
European Union regulatory compliance
EVA-8M, EVA-M8M, and EVA-M8Q comply with all relevant requirements for RED 2014/53/EU. The EVA-8M and EVA-M8M/Q
Declaration of Conformity (DoC) is available at www.u-blox.com within Support > Product resources > Conformity Declaration.
This document applies to the following products:
Product name Type number ROM/FLASH version PCN reference
EVA-M8M EVA-M8M-0-10 ROM SPG 3.01 / Flash FW SPG 3.01 UBX-16012546
EVA-M8M EVA-M8M-1-10 ROM SPG 3.01 / Flash FW SPG 3.01 UBX-16012546
EVA-M8Q EVA-M8Q-0-10 ROM SPG 3.01 / Flash FW SPG 3.01 N/A
EVA-8M EVA-8M-0-10 ROM SPG 3.01 N/A
u-blox or third parties may hold intellectual property rights in the products, names, logos and designs included in this
document. Copying, reproduction, modification or disclosure to third parties
of this document or any part thereof is only
permitted with the express written permission of u
-blox.
The information contained herein is provided “as is” and u
-blox assumes no liability for its use. No warranty, either express or
implied, is given, includ
ing but not limited to, with respect to the accuracy, correctness, reliability and fitness for a particular
purpose of the information. This document may be revised by u
-blox at any time without notice. For the most recent
documents, visit www.u
-blox.com.
Copyright © u
-blox AG.

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Contents
Document Information................................................................................................................................ 2
Contents .......................................................................................................................................................... 3
1Hardware description ........................................................................................................................... 6
1.1 Overview........................................................................................................................................................6
2Design-in................................................................................................................................................... 7
2.1 Power management ...................................................................................................................................7
2.1.1 Overview ...............................................................................................................................................7
2.1.2 Power management configuration .................................................................................................8
2.2 Interfaces......................................................................................................................................................9
2.2.1 UART interface....................................................................................................................................9
2.2.2 Display Data Channel (DDC) Interface .........................................................................................10
2.2.3 SPI Interface ......................................................................................................................................10
2.2.4 USB interface.....................................................................................................................................10
2.2.5 SQI Flash memory.............................................................................................................................11
2.3 I/O Pins ........................................................................................................................................................12
2.3.1 Time pulse..........................................................................................................................................12
2.3.2 External interrupt .............................................................................................................................13
2.3.3 Active antenna supervisor..............................................................................................................13
2.3.4 Electromagnetic interference and I/O lines.................................................................................14
2.4 Real-Time Clock (RTC) .............................................................................................................................15
2.4.1 RTC using a crystal...........................................................................................................................15
2.4.2 RTC derived from the system clock: “single crystal” feature..................................................15
2.4.3 RTC using an external clock ...........................................................................................................15
2.4.4 Time aiding.........................................................................................................................................16
2.5 RF input.......................................................................................................................................................16
2.5.1 Active Antenna..................................................................................................................................16
2.5.2 Passive Antenna ...............................................................................................................................16
2.5.3 Improved Jamming Immunity........................................................................................................17
2.6 Safe Boot Mode (SAFEBOOT_N) ...........................................................................................................17
2.7 System Reset (RESET_N) .......................................................................................................................18
2.8 Design-in checklist....................................................................................................................................18
2.8.1 General considerations....................................................................................................................18
2.8.2 Schematic design-in for EVA-8M / EVA-M8 series GNSS modules.......................................18
2.9 Pin description...........................................................................................................................................19
2.9.1 Pin name changes.............................................................................................................................20
2.10Layout design-in checklist ......................................................................................................................20
2.11Layout..........................................................................................................................................................21
2.11.1 Footprint.............................................................................................................................................21
2.11.2 Paste mask ........................................................................................................................................21
2.11.3 Placement ..........................................................................................................................................22

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2.12Migration considerations ........................................................................................................................22
2.12.1 Hardware migration from EVA-7M to EVA-8M / EVA-M8M / EVA-M8Q ..............................22
2.12.2 C88-M8M - Evaluating EVA-M8M on existing NEO-xM sockets............................................24
2.13EOS/ESD/EMI precautions......................................................................................................................25
2.13.1 Electrostatic Discharge (ESD) .......................................................................................................26
2.13.2 ESD protection measures...............................................................................................................26
2.13.3 Electrical Overstress (EOS) ............................................................................................................26
2.13.4 EOS protection measures...............................................................................................................26
2.13.5 Electromagnetic interference (EMI) .............................................................................................27
2.13.6 Applications with cellular modules ...............................................................................................27
3Product handling & soldering.......................................................................................................... 30
3.1 Packaging, shipping, storage and moisture preconditioning ..........................................................30
3.2 ESD handling precautions.......................................................................................................................30
3.3 Soldering .....................................................................................................................................................30
3.3.1 Soldering paste .................................................................................................................................30
3.3.2 Reflow soldering................................................................................................................................31
3.3.3 Optical inspection.............................................................................................................................31
3.3.4 Repeated reflow soldering ..............................................................................................................31
3.3.5 Wave soldering..................................................................................................................................31
3.3.6 Rework ................................................................................................................................................31
3.3.7 Use of ultrasonic processes ...........................................................................................................31
4Product testing ................................................................................................................................... 32
4.1 Test parameters for OEM manufacturer.............................................................................................32
4.2 System sensitivity test............................................................................................................................32
4.2.1 Guidelines for sensitivity tests ......................................................................................................32
4.2.2‘Go/No go’ tests for integrated devices........................................................................................32
Appendix ....................................................................................................................................................... 33
AReference schematics....................................................................................................................... 33
A.1 Cost optimized circuit..............................................................................................................................33
A.2 Best performance circuit with passive antenna.................................................................................34
A.3 Improved jamming immunity with passive antenna .........................................................................35
A.4 Circuit using active antenna...................................................................................................................36
A.5 USB self-powered circuit with passive antenna .................................................................................37
A.6 USB bus-powered circuit with passive antenna .................................................................................38
A.7 Circuit using 2-pin antenna supervisor ................................................................................................39
A.8 Circuit using 3-pin antenna supervisor ................................................................................................40
BComponent selection ........................................................................................................................ 41
B.1 External RTC (Y1)......................................................................................................................................41
B.2 RF band-pass filter (F1)...........................................................................................................................41
B.3 External LNA protection filter (F2)........................................................................................................42
B.4 USB line protection (D2) ..........................................................................................................................42
B.5 USB LDO (U1).............................................................................................................................................42

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B.6 External LNA (U1) .....................................................................................................................................42
B.7 Optional SQI Flash (U3)............................................................................................................................43
B.8 RF ESD protection diode (D2).................................................................................................................43
B.9 Operational amplifier (U6).......................................................................................................................43
B.10Open-drain buffer (U4, U7 and U8)........................................................................................................43
B.11Antenna supervisor switch transistor (T1) .........................................................................................44
B.12Ferrite beads (FB1) ...................................................................................................................................44
B.13Feed-thru capacitors................................................................................................................................44
B.14Inductor (L1)...............................................................................................................................................44
B.15Standard capacitors.................................................................................................................................44
B.16Standard resistors....................................................................................................................................45
CGlossary ................................................................................................................................................. 45
Related documents ................................................................................................................................... 46
Revision history .......................................................................................................................................... 46
Contact.......................................................................................................................................................... 47

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1Hardware description
1.1 Overview
The EVA-8M / EVA-M8 series GNSS modules feature the excellent performance of the u-blox 8 / u-
blox M8 positioning engine. The EVA-8M / EVA-M8 series delivers high sensitivity and minimal
acquisition times in the ultra-compact EVA form factor.
The EVA-8M / EVA-M8 series is an ideal solution for cost and space-sensitive applications. It is easy
to design-in, only requiring an external GNSS antenna in most applications. The layout of the EVA-8M
/ EVA-M8 modules is especially designed to ease the customer’s design and limit near field
interferences since RF and digital domains are kept separated.
The EVA-8M and EVA-M8M series module uses a crystal oscillator for lower system costs, while EVA-
M8Q with TCXO provides best performance. Like other u-blox GNSS modules, the EVA series uses
components selected for functioning reliably in the field over the full operating temperature range.
The EVA-M8M and EVA-M8Q modules include a dual-frequency RF front-end, with which the u-blox
M8 concurrent GNSS engine is able to intelligently use the highest amount of visible satellites from
up to three GNSS (GPS/Galileo, together with GLONASS or BeiDou) systems for reliable positioning.
The EVA-M8M series comes in two variants. The EVA-M8M-0 defaults to GPS/QZSS/GLONASS and
fits global applications, whereas EVA-M8M-1 defaults to GPS/QZSS/BeiDou making it the ideal
module for China. The right satellite constellations can be selected without touching software, and
therefore reducing the design and testing effort.
The EVA-8M includes a single-frequency RF front-end, and can receive and track either GPS or
GLONASS signals.
The EVA-8M and EVA-M8 series modules can be easily integrated in manufacturing, thanks to the
QFN-like package and low moisture sensitivity level. The modules are available in 500 pcs/reel, ideal
for small production batches. The EVA-8M and EVA-M8 series modules combine a high level of
integration capability with flexible connectivity options in a miniature package. This makes them
perfectly suited for industrial and mass-market end products with strict size and cost requirements.
The DDC (I2C compliant) interface provides connectivity and enables synergies with u-blox cellular
modules.
The EVA-8M and EVA-M8 series modules are qualified as stipulated in the JESD47 standard.
☞For applications needing data logging capability, storing configurations and hold AssistNow data,
the EVA-8M / EVA-M8 series GNSS modules must be connected to an external SQI Flash memory.
Firmware update form SQI Flash memory is only supported with EVA-M8M and EVA-M8Q series
GNSS modules. For more information about product features, see the
EVA-M8 Data Sheet [1] and
the
EVA-8M Data Sheet [2]
☞To determine which u-blox product best meets your needs, see the product selector tables on the
u-blox website www.u-blox.com.

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2Design-in
In order to obtain good performance with EVA-8M / EVA-M8 series GNSS receiver modules, there are
a number of issues requiring careful attention during the design-in. These include:
•Power Supply: Good performance requires a clean and stable power supply.
•Interfaces: Ensure correct wiring, rate and message setup on the module and your host system.
•Antenna interface: For optimal performance, seek short routing, matched impedance and no stubs.
•External LNA: With EVA-M8 and EVA-M8M modules, an additional external LNA is mandatory if a
passive antenna is used. With EVA-M8Q module, an additional external LNA is
recommended with passive antenna.
2.1 Power management
2.1.1 Overview
The EVA-8M / EVA-M8 series GNSS modules provide four supply pins: VCC, VCC_IO, V_BCKP and
VDD_USB. They can be supplied independently or tied together to adapt various concepts, depending
on the intended application. The different supply voltages are explained in the following subsections.
Figure 1 shows an example to supply the EVA-8M / EVA-M8 series modules when not using the USB
interface. In this case, the VDD_USB pin is connected to ground.
Figure 1: EVA-8M / EVA-M8 series power supply example
2.1.1.1 Main supply voltage (VCC)
During operation, the EVA-8M / EVA-M8 series GNSS modules are supplied through the VCC pin. It
makes use of an internal DC/DC converter for improved power efficiency. In a following step, built-in

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LDOs generate stabilized voltages for the Core and RF domains of the chip respectively. The current
at VCC depends heavily on the current state of the system and is in general very dynamic.
☞Do not add any series resistance (< 0.2 Ω) to the VCC supply, as it will generate input voltage noise
due to the dynamic current conditions.
☞The equipment must be supplied by an external limited power source in compliance with the clause
2.5 of the standard IEC 60950-1.
2.1.1.2 I/O supply voltage (VCC_IO)
The digital I/Os of the EVA-8M / EVA-M8 series GNSS modules can be supplied with a separate voltage
from the host system connected to the VCC_IO pin of the module. The wide range of VCC_IO allows
seamless interfacing to standard logic voltage levels. However, in most applications VCC_IO and VCC
share the same voltage level and are tied together. VCC_IO supplies also the RTC and the backup RAM
(BBR) during normal operation.
The EVA-8M / EVA-M8 series GNSS modules come in two different IO voltage range flavors:
1. EVA-M8Q with IO voltage from 2.7 V to 3.6 V
2. EVA-M8M and EVA-8M with the wider range from 1.65 V to 3.6 V. The level should be set
according to section 2.2.5.
☞VCC_IO must be supplied in order for the system to boot.
☞When running the firmware from the external SQI Flash most of the VCC_IO current is consumed
by the SQI bus.
2.1.1.3 Backup power supply (V_BCKP)
In the event of a power failure at VCC_IO, the backup domain is supplied by V_BCKP.
☞If no backup supply is available, connect V_BCKP to VCC_IO.
☞Avoid high resistance on the V_BCKP line: During the switch from main supply to backup supply,
a short current adjustment peak can cause high voltage drop on the pin with possible
malfunctions.
☞If the “single crystal” feature is enabled (which derives the RTC frequency from the main clock),
the V_BCKP pin also supplies the clock domain if there is a power failure at VCC_IO, meaning that
the V_BCKP current will also be higher. Ensure that the capacity of the backup battery chosen
meets your requirements. EVA-M8Q module uses TCXO oscillator and does not support the
“single crystal” feature. For more information about “single crystal” feature see section 2.4.2
2.1.1.4 USB interface power supply
VDD_USB supplies I/Os of the USB interface. If the USB interface is being used, the system can be
either self-powered, i.e. powered independently from the USB bus, or it can be bus-powered, i.e.
powered through the USB connection. In bus-powered mode, the system supply voltages need to be
generated from the USB supply voltage VBUS.
☞If the USB interface is not used, the VDD_USB pin must be connected to GND.
2.1.2 Power management configuration
Depending on the application, the power supply schematic will differ. Some examples are shown in the
following sections:
•Single supply voltage for VCCand VCC_IO, no backup supply see Appendix, Figure 13
•Separate supply voltages for VCC, VCC_IO and V_BCKP see Appendix, Figure 14
•Single supply voltage for VCC and VCC_IO, use of a backup supply see Appendix, Figure 16

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☞For description of the different power operating modes see the EVA-M8 Data Sheet [1] and the
EVA-8M Data Sheet [2].
2.2 Interfaces
The EVA-8M / EVA-M8 series GNSS modules provide UART, SPI and DDC (I2C compatible) interfaces
for communication with a host CPU. A USB interface is also available on dedicated pins (see section
2.2.4). Additionally, an SQI interface is available for connecting the EVA-8M / EVA-M8 series GNSS
modules with an optional external flash memory.
The UART, SPI and DDC pins are supplied by VCC_IO and operate at this voltage level.
Four dedicated pins can be configured as either 1 x UART and 1 x DDC or a single SPI interface
selectable by D_SEL pin. Table 1 below provides the port mapping details.
Pin 32 (D_SEL) = “high” (left open) Pin 32 (D_SEL) = “Low” (connected to GND)
UART TXD SPI MISO
UART RXD SPI MOSI
DDC SCL SPI CLK
DDC SDA SPI CS_N
Table 1: Communication Interfaces overview
☞It is not possible to use the SPI interface simultaneously with the DDC or UART interface.
☞For debugging purposes, it is recommended to have a second interface e.g. USB available that is
independent from the application and accessible via test-points.
For each interface, a dedicated pin can be defined to indicate that data is ready to be transmitted.
The TXD Ready signal indicates that the receiver has data to transmit. Each TXD Ready signal is
associated with a particular interface and cannot be shared. A listener can wait on the TXD Ready
signal instead of polling the DDC or SPI interfaces. The UBX-CFG-PRT message lets you configure the
polarity and the number of bytes in the buffer before the TXD Ready signal goes active. The TXD Ready
function is disabled by default.
☞The TXD Ready functionality can be enabled and configured by proper AT commands sent to the
involved u-blox cellular module supporting the feature. For more information see the
GPS
Implementation and Aiding Features in u-blox wireless modules
[6].
☞The TXD Ready feature is supported on several u-blox cellular module products.
2.2.1 UART interface
A UART interface is available for serial communication to a host CPU. The UART interface supports
configurable data rates with the default at 9600 baud. Signal levels are related to the VCC_IO supply
voltage. An interface based on RS232 standard levels (+/- 7 V) can be realized using level shifter ICs
such as the Maxim MAX3232.
Hardware handshake signals and synchronous operation are not supported.
A signal change on the UART RXD pin can also be used to wake up the receiver in Power Save Mode
(see the
u-blox 8 / u-blox M8 Receiver Description Including Protocol Specification [3]).
☞Designs must allow access to the UART and the SAFEBOOT_N pin for future service, updates, and
reconfiguration.

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2.2.2 Display Data Channel (DDC) Interface
An I2C compatible Display Data Channel (DDC) interface is available for serial communication with a
host CPU.
☞The SCL and SDA pins have internal pull-up resistors sufficient for most applications. However,
depending on the speed of the host and the load on the DDC lines additional external pull-up
resistors might be necessary. For speed and clock frequency see the
EVA-M8 Data Sheet [1] and
the
EVA-8M Data Sheet [2].
☞To make use of DDC interface the D_SEL pin has to be left open.
☞The EVA-8M / EVA-M8 series GNSS modules DDC interface provides serial communication with
u-blox cellular modules. See the specification of the applicable cellular module to confirm
compatibility.
2.2.3 SPI Interface
The SPI interface can be used to provide a serial communication with a host CPU. If the SPI interface
is used, UART and DDC are deactivated, because they share the same pins.
☞To make use of the SPI interface, the D_SEL pin has to be connected to GND.
2.2.4 USB interface
The USB interface of the EVA-8M / EVA-M8 series GNSS modules support the full-speed data rate of
12 Mbit/s. It is compatible to the USB 2.0 FS standard. The interface requires some external
components in order to implement the physical characteristics required by the USB 2.0 specification.
Figure 2 shows the interface pins and additional external components. In order to comply with USB
specifications, VBUS must be connected through a LDO (U1) to pin VDD_USB of the module. This
ensures that the internal 1.5kΩpull-up resistor on USB_DP gets disconnected when the USB host
shuts down VBUS.
Depending on the characteristics of the LDO (U1), for a self-powered design it is recommended to add
a pull-down resistor (R8) at its output to ensure VDD_USB does not float if a USB cable is not
connected, i.e. when VBUS is not present. In USB self-powered mode, the power supply (VCC) can be
turned off and the digital block is not powered. In this case, since VBUS is still available, the USB host
would still receive the signal indicating that the device is present and ready to communicate. This
should be avoided by disabling the LDO (U1) using the enable signal (EN) of the VCC-LDO or the output
of a voltage supervisor.
The interface can be used either in “self-powered” or “bus-powered” mode. The required mode can be
configured using the UBX-CFG-USB message. Also, the vendor ID, vendor string, product ID and
product string can be changed.
In order to get the 90Ωdifferential impedance in between the USB_DM and USB_DP data line, a 27Ω
series resistor (R4, R5) must be placed into each data line (USB_DM and USB_DP).
Module
VDD_USB
LDO
VDD_USB
R4
USB_DP
USB_DM
R5
C24 C23
D2
VBUS
DP
DM
GND
USB Device Connector
U1
EN R11
EN
Figure 2: USB interface

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Name Component Function Comments
U1 LDO Regulates VBUS (4.4 …5.25
V) down to a voltage of 3.3 V).
Almost no current requirement (~1 mA) if the GNSS receiver is
operated as a USB self-powered device, but if bus-powered LDO (U1)
must be able to deliver the maximum current of ~100 mA.
C24,C23 Capacitors Required according to the specification of LDO U1
D2 Protection
diodes
Protect circuit from
overvoltage / ESD when
connecting.
Use low capacitance ESD protection such as ST Microelectronics
USBLC6-2.
R4, R5 Serial
termination
resistors
Establish a full-speed driver
impedance of 28…44 Ω
A value of 27
Ω
is recommended.
R11 Resistor Ensures defined signal at
VDD_USB when VBUS is not
connected / powered
100 k
Ω
is recommended for USB self-powered setup. For bus-powered
setup R8 is not required.
Table 2: Summary of USB external components
See Appendix A.5 and Appendix A.6 for reference schematics for self- and bus-powered operation.
☞If the USB interface is not used, connect VDD_USB to GND.
2.2.5 SQI Flash memory
An external SQI (Serial Quad Interface) Flash memory can be connected to the EVA-8M / EVA-M8
series GNSS modules. The SQI interface provides the following options:
•Store the current configuration permanently
•Save data logging results
•Hold AssistNow Offline and AssistNow Autonomous data
☞In addition, the EVA-M8M and EVA-M8Q GNSS modules can make use of a dedicated flash
firmware with an external SQI Flash memory. The flash memory with these modules can be used
to run firmware out of flash and to update the firmware as well. Running the firmware from the
SQI Flash requires a minimum SQI Flash size of 8 Mbit.
☞The voltage level of the SQI interface follows the VCC_IO level. Therefore, the SQI Flash must be
supplied with the same voltage as VCC_IO of the EVA-8M / EVA-M8 module. It is recommended to
place a decoupling capacitor (C4) close to the supply pin of the SQI Flash.
☞Make sure that the SQI Flash supply range matches the voltage supplied at VCC_IO.
Figure 3 : Connecting an external SQI Flash memory

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SQI Flash size of 8 Mbit is sufficient to save AssistNow Offline and AssistNow Autonomous
information as well as current configuration data. However, for EVA-M8M and EVA-M8Q to run
Firmware from the SQI Flash and provide space for logging results, a minimum size of 8 Mbit may not
be sufficient depending on the amount of data to be logged.
☞For more information about supported SQI Flash devices see Table 18.
EVA-8M / EVA-M8 series modules have a configurable VCC_IO monitor threshold (iomonCfg) to
ensure that the module only start if the VCC_IO supply is within the supply range of the SQI Flash
device (VCC_IO is used to supply the SQI Flash). This will ensure that any connected SQI Flash memory
will be detected correctly at startup.
See the
u-blox 8 / u-blox M8 Receiver Description Including Protocol Specification [3] for setting the
iomonCfg value.
With EVA-8M and EVA-M8M modules the VCC_IO monitor threshold is set to default 1.54 V value for
using a 1.8 V Flash memory device.
With EVA-M8Q module, the VCC_IO monitor threshold is set to default 2.69 V value in production, but
may be increased to 3.0 V.
If the default value for the VCC_IO monitor threshold is not suitable it can be set according to the IO
supply voltage level (VCC_IO) in the eFuse by the Low Level Configuration.
If VCC_IO voltage 2.7 V to 3.0 V is used, send the following sequence to the module
•B5 62 06 41 0C 00 00 00 03 1F 04 BA CF 67 FF 7F FF FF E5 95
If VCC_IO voltage 3.0 V to 3.6 V is used, send the following sequence to the module
•B5 62 06 41 0C 00 00 00 03 1F 4F 22 4C 5C FF 7F 7F FF 8A 7C
☞Applying these sequences result in a permanent change and cannot be reversed. An unstable
supply voltage at the VCC_IO pin while applying these sequences can also damage the receiver.
☞Make sure that the SAFEBOOT_N pin is available for entering Safe Boot Mode. Programming the
SQI Flash memory with a Flash firmware is done typically at production. For this purpose the EVA-
M8M and EVA-M8Q GNSS modules have to enter the Safe Boot Mode. More information about
SAFEBOOT_N pin see section 2.6.
☞When the EVA-M8M-1 variant is attached with an external SQI flash without running a Flash
firmware, the default concurrent reception of GPS/QZSS/SBAS and BeiDou remains unchanged.
In case the Flash is also used for execution of firmware update, the default reception will be reset
to GPS/QZSS/SBAS and GLONASS. EVA-M8M-1 can be changed back to concurrent
GPS/QZSS/SBAS and BeiDou by sending a dedicated UBX message (UBX-CFG-GNSS) to the
module. More information see the
u-blox 8 / ublox M8 Receiver Description Including Protocol
Specification
[3].
2.3 I/O Pins
All I/O pins make use of internal pull-ups. Thus, there is no need to connect unused pins to VCC_IO.
2.3.1 Time pulse
A configurable time pulse signal is available with the EVA-8M / EVA-M8 series GNSS modules.
The TIMEPULSE output generates pulse trains synchronized with GPS or UTC time grid with intervals
configurable over a wide frequency range. Thus it may be used as a low frequency time
synchronization pulse or as a high frequency reference signal.

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By default, the time pulse signal is disabled. For more information, see the u-blox 8 / u-blox M8
Receiver Description Including Protocol Specification
[3].
2.3.2 External interrupt
EXTINT is an external interrupt pin with fixed input voltage thresholds with respect to VCC_IO (see
the
EVA-M8 Data Sheet [1] and the EVA-8M Data Sheet [2] for more information). It can be used for
wake-up functions in Power Save Mode on all u-blox M8 modules and for aiding. Leave open if unused;
its function is disabled by default. By default, the external interrupt is disabled.
If the EXTINT is not used for an external interrupt function, it can be used for some other purpose.
E.g. as an output pin for the TXD Ready feature to indicate that the receiver has data to transmit.
For further information, see the pin assignment in section 2.9 and the u-blox 8 / u-blox M8 Receiver
Description Including Protocol Specification [3].
☞If the EXTINT is configured for on/off switching of the EVA-8M / EVA-M8 series GNSS modules,
the internal pull-up becomes disabled. Thus make sure the EXTINT input is always driven within
the defined voltage level by the host.
2.3.3 Active antenna supervisor
The EVA-8M / EVA-M8 series GNSS modules support active antenna supervisors. The antenna
supervisor gives information about the status of the active antenna and will turn off the supply to the
active antenna in case a short is detected or to optimize the power consumption when in Power Save
Mode.
There is either a 2-pin or a 3-pin antenna supervisor. By default the 2-pin antenna supervisor is
enabled.
2.3.3.1 2-pin antenna supervisor
The 2-pin antenna supervisor function, which is enabled by default, consists of the ANT_OK input and
the ANT_OFF output pins.
Function I/O Description Remarks
ANT_OK I Antenna OK
“high” = Antenna OK
“low” = Antenna not OK
Default configuration
ANT_OFF O Control signal to turn on and off the antenna supply
“high” = Antenna OFF
“low” = Antenna ON
Default configuration
Table 3: 2-pin antenna supervisor pins
The circuitry, as shown in Appendix A.7 (see Figure 19) provides antenna supply short circuit
detection. It will prevent antenna operation via transistor T1 if a short circuit has been detected or if
it is not required (e.g. in Power Save Mode).
The status of the active antenna can be checked by the UBX-MON-HW message. For more
information, see the
u-blox 8 / u-blox M8 Receiver Description Including Protocol Specification [3].
Open drain buffers U4 and U7 (e.g. Fairchild NC7WZ07) are needed to shift the voltage levels. R3 is
required as a passive pull-up to control T1 because U4 has an open drain output. R4 serves as a
current limiter in the event of a short circuit.

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2.3.3.2 3-pin antenna supervisor
The 3-pin antenna supervisor is comprised of the ANT_DET (active antenna detection), ANT_OK
(short detection) and ANT_OFF (antenna on/off control) pins. This function must be activated by
sending the following sequence to the EVA-8M / EVA-M8 series receivers in production:
•B5 62 06 41 0C 00 00 00 03 1F CD 1A 38 57 FF FF F6 FF DE 11
☞Applying this sequence results in a permanent change and cannot be reversed. An unstable supply
voltage at the VCC_IO pin while applying this sequence can also damage the receiver.
Function I/O Description Remarks
ANT_DET I
(pull-up)
Antenna detected
“high” = Antenna detected
“low” = Antenna not detected
Byte sequence given in section 2.3.3.2
should be applied.
ANT_OK I
(pull-up)
Antenna not shorted
“high” = antenna has no short
“low” = antenna has a short
Byte sequence given in section 2.3.3.2
should be applied.
ANT_OFF O Control signal to turn on and off the antenna
supply
“high” = turn off antenna supply
“low” = short to GND
Byte sequence given in section 2.3.3.2
should be applied.
Table 4: 3-pin Antenna supervisor pins
The external circuitry, as shown in Appendix A.8, (see Figure 20) provides detection of an active
antenna connection status. If the active antenna is present, the DC supply current exceeds a preset
threshold defined by R4, R5, and R6. It will shut down the antenna via transistor T1 if a short circuit
has been detected via U7 or if it’s not required (e.g. in Power Save Mode).
The status of the active antenna can be checked by the UBX-MON-HW message. More information
see the
u-blox 8 / u-blox M8 Receiver Description Including Protocol Specification [3].
The open drain buffers U4, U7 and U8 (e.g. Fairchild NC7WZ07) are needed to shift the voltage levels.
R3 is required as a passive pull-up to control T1 because U4 has an open drain output. R4 serves as a
current limiter in the event of a short circuit.
2.3.4 Electromagnetic interference and I/O lines
Any I/O signal line (length > ~3 mm) can act as an antenna and may pick up arbitrary RF signals
transferring them as noise into the GNSS receiver. This specifically applies to unshielded lines, lines
where the corresponding GND layer is remote or missing entirely, and lines close to the edges of the
printed circuit board. If for example, a cellular signal radiates into an unshielded high-impedance line,
it is possible to generate noise in the order of volts and not only distort receiver operation but also
damage it permanently.
On the other hand, noise generated at the I/O pins will emit from unshielded I/O lines. Receiver
performance may be degraded when this noise is coupled into the GNSS antenna (see Figure 9).
In case of improper shielding, it is recommended to use resistors or ferrite beads (see Appendix B.12)
on the I/O lines in series. These components should be chosen with care because they will affect also
the signal rise times. Alternatively, feed-thru capacitors with good GND connection close to the GNSS
receiver can be used (see Appendix B.13).
EMI protection measures are particularly useful when RF emitting devices are placed next to the
GNSS receiver and/or to minimize the risk of EMI degradation due to self-jamming. An adequate
layout with a robust grounding concept is essential in order to protect against EMI. More information
can be found in subsection 2.13.6.3.

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2.4 Real-Time Clock (RTC)
The use of the RTC is optional to maintain time in the event of power failure at VCC_IO. The RTC is
required for hot start, warm start, AssistNow Autonomous, AssistNow Offline and in some Power
Save Mode operations. The time information can either be generated by connecting an external RTC
crystal to the module, by deriving the RTC from the internal crystal oscillator, by connecting an
external 32.768 kHz signal to the RTC input, or by time aiding of the GNSS receiver at every startup.
If a power save mode is used then an external RTC crystal must be connected. Optionally the RTC
frequency can be derived from the system clock or an external 32.768 kHz signal can be provided.
2.4.1 RTC using a crystal
The easiest way to provide time information to the receiver is to connect an RTC crystal to the
corresponding pins of the RTC oscillator, RTC_I and RTC_O. There is no need to add load capacitors
to the crystal for frequency tuning, because they are already integrated in the chip. Using an RTC
crystal will provide the lowest current consumption to V_BCKP in case of a power failure. On the other
hand, it will increase the BOM costs and requires space for the RTC crystal.
Figure 4: RTC crystal
2.4.2 RTC derived from the system clock: “single crystal” feature
The crystal based EVA-8M / EVA-M8M GNSS modules can be configured in such way that the
reference frequency for the RTC is internally derived from the 26 MHz crystal oscillator. For this
feature RTC_I must be connected to ground and RTC_O left open. The capacity of the backup battery
at V_BCKP must be dimensioned accordingly, taking into account the higher than normal current
consumption at V_BCKP in the event of power failure at VCC_IO.
☞Deriving RTC clock from internal oscillator is not available on TCXO based EVA-M8Q module.
☞With EVA-8M / EVA-M8M modules the single crystal feature can be configured by sending the
following sequence to the receiver:
B5 62 06 41 0C 00 00 00 03 1F 06 C3 CC B4 FF FF FD FF B8 CF
☞Applying this sequence results in a permanent change and cannot be reversed. An unstable supply
voltage at the VCC_IO pin while applying this sequence can also damage the receiver.
2.4.3 RTC using an external clock
Some applications can provide a suitable 32.768 kHz external reference to drive the module RTC. The
external reference can simply be connected to the RTC_I pin. Make sure that the 32.768 kHz reference
signal is always turned on and the voltage at the RTC_I pin does not exceed 350 mVpp. Adjusting of
the voltage level (typ. 200 mVpp) can be achieved with a resistive voltage divider followed by a DC
blocking capacitor in the range of 1 nF to 10 nF. Also make sure the frequency versus temperature
behavior of the external clock is within the recommended crystal specification shown in section B.1.

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2.4.4 Time aiding
Time can also be sent by UBX message at every startup of the EVA-8M / EVA-M8 series GNSS
modules. This can be done to enable warm starts, AssistNow Autonomous and AssistNow Offline.
This can be done when no RTC is maintained.
To enable hot starts correctly, the time information must be known accurately and thus the
TimeMark feature has to be used.
For more information about time aiding or timemark see the
u-blox 8 / u-blox M8 Receiver Description
Including Protocol Specification
[3].
☞For information of this use case, it is mandatory to contact u-blox support team.
☞For Power Save Mode operations where the RTC is needed, the time aiding cannot be used. This is
because the host does not have any information about when the EVA-8M / EVA-M8 series GNSS
modules turn from OFF status to ON status during ON/OFF operation of Power Save Mode.
2.5 RF input
The EVA-8M / EVA-M8 series GNSS module RF-input is already matched to 50 Ωand has an internal
DC block. To achieve the performance values as written in the
EVA-M8 Data Sheet [1] and the EVA-
8M Data Sheet
[2], an active antenna with a good LNA inside or the mandatory LNA with passive
antenna in front of EVA-8M / EVA-M8M GNSS module (must have a noise figure below 1dB). EVA-
M8Q with the passive antenna an external LNA is only recommended.
The EVA-M8 series GNSS modules can receive and track multiple GNSS system (e.g. GPS, Galileo,
GLONASS, BeiDou and QZSS signals). Because of the dual-frequency RF front-end architecture, two
GNSS signals (GPS L1C/A, GLONASS L1OF, Galileo E1B/C and BeiDou B1) can be received and
processed concurrently. This concurrent operation is extended to 3 GNSS when GPS and Galileo are
used in addition to GLONASS or BeiDou
The EVA-8M can receive GPS L1C/A and GLONASS L1OF signals. However, because of differing
center frequencies, the receiver has to be switched to GPS or GLONASS mode by using a UBX
message.
☞Concurrent reception of both GPS and GLONASS is not possible with the EVA-8M.
2.5.1 Active Antenna
In case an active antenna is used, just the active antenna supply circuit has to be added in front of the
modules RF-input, see Figure 16. In case the active antenna has to be supervised, either the 2-pin
active antenna supervisor circuit (see Figure 19) or the 3-pin active antenna supervisor circuit (see
Figure 20), has to be added to the active antenna circuit. These active antenna supervisor circuits also
make sure that the active antenna is turned off in Power Save Mode stages.
2.5.2 Passive Antenna
If a passive antenna is connected to a EVA-8M / EVA-M8M series GNSS module, it is mandatory to
use an additional LNA in front of module to achieve the performance values as written in the
EVA-M8
Data Sheet
[1] and the EVA-8M Data Sheet [2], see Annex A. EVA-M8Q with passive antenna, an
external LNA is only recommended. An LNA (U1) alone would make the modules more sensitive to out-
band jammers, so an additional GNSS SAW filter (F1) has to be connected between the external LNA
(U1) and the EVA-8M / EVA-M8M series GNSS module RF-input. If strong out-band jammers are close
to the GNSS antenna (e.g. a GSM antenna), see section 2.5.3.
The LNA (U1) can be selected to deliver the performance needed by the application in terms of:
•Noise figure (sensitivity)

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•Selectivity and linearity (Robustness against jamming)
•Robustness against RF power and ESD
☞The external LNA (U1) must be placed close to the passive antenna to get best performance.
If Power Save Mode is used and the minimum current consumption has to be achieved, then the
external LNA should also be turned off. The ANT_OFF pin can be used to turn off an external LNA.
The ANT_OFF signal must be inverted for common LNAs which come with an enable pin which has be
“low” to turn off.
☞The function of the ANT_OFF pin can be inverted by sending the following sequence to the
receiver:
B5 62 06 41 0C 00 00 00 03 1F 90 47 4F B1 FF FF EA FF 33 98
☞Applying this sequence results in a permanent change and cannot be reversed. An unstable supply
voltage at the VCC_IO pin while applying this sequence can also damage the receiver.
☞A pull-down resistor (R7) is required to ensure correct operation of the ANT_OFF pin.
ESD discharge into the RF input cannot always be avoided during assembly and / or field use with this
approach! To provide additional robustness an ESD protection diode, as listed in Appendix B.7, can be
placed in front of the LNA to GND.
2.5.3 Improved Jamming Immunity
If strong out-band jammers are close to the GNSS antenna (e.g. a GSM antenna) GNSS performance
can be degraded or the maximum input power of the EVA-8M / EVA-M8 series GNSS modules RF-
input can be exceeded. An additional SAW filter (F2) has to put in front of the external LNA (U1), see
Appendix A. If the external LNA can accept the maximum input power, the SAW filter between the
passive antenna and external LNA (LNA1) might not be necessary. This results in a better noise figure
than an additional SAW filter (F2) in front of the external LNA (U1).
If the EVA-8M / EVA-M8 series GNSS module is exposed to an interference environment, it is
recommended to use additional filtering. Improved interference immunity with good GNSS
performance can be achieved when using a SAW/LNA/SAW configuration between the antenna and
the RF-input. The single-ended SAW filter (F2) can be placed in front of the LNA matching network to
prevent receiver blocking due to strong interference, see Figure 15.
It should be noted that the insertion loss of SAW filter (F2) directly affects the system noise figure
and hence the system performance. Choice of a component with low insertion loss is mandatory when
a passive antenna is used with this set-up. An example schematic for an improved jamming immunity
is shown in Appendix A.3 (see Figure 15).
2.6 Safe Boot Mode (SAFEBOOT_N)
If the SAFEBOOT_N pin is “low” at start up, the EVA-8M / EVA-M8 series GNSS modules start in Safe
Boot Mode and doesn’t begin GNSS operation. In Safe Boot Mode the module runs from an internal
LC oscillator and starts regardless of any configuration provided by the configuration pins. Thus, it
can be used to recover from situations where the SQI Flash has become corrupted.
Owing to the inaccurate frequency of the internal LC oscillator, the module is unable to communicate
via USB in Safe Boot Mode. For communication by UART in Safe Boot Mode, a training sequence (0x
55 55 at 9600 baud) can be sent by the host to the EVA-8M / EVA-M8 series GNSS modules in order
to enable communication. After sending the training sequence, the host has to wait for at least 2 ms
before sending messages to the receiver. For further information see the
u-blox 8 / u-blox M8 Receiver
Description Including Protocol Specification
[3].

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Safe Boot Mode is used in production to program the SQI Flash. It is recommended to have the
possibility to pull the SAFEBOOT_N pin “low” when the module starts up. This can be provided using
an externally connected test point or via a host CPUs digital I/O port.
2.7 System Reset (RESET_N)
The EVA-8M / EVA-M8 series GNSS modules provide a RESET_N pin to reset the system. The
RESET_N is an input-only with internal pull-up resistor. It must be at low level for at least 10 ms to
make sure RESET_N is detected. It is used to reset the system. Leave RESET_N open for normal
operation. The RESET_N complies with the VCC_IO level and can be actively driven high.
☞RESET_N should be only used in critical situations to recover the system. The Real-Time Clock
(RTC) will also be reset and thus immediately afterwards the receiver cannot perform a Hot Start.
☞In reset state, the module consumes a significant amount of current. It is therefore recommended
to use RESET_N only as a reset signal and not as an enable/disable.
2.8 Design-in checklist
2.8.1 General considerations
Check power supply requirements and schematic:
Is the power supply voltage within the specified range? See how to connect power in Section 2.1.
For USB devices: Is the voltage VDD_USB voltage within the specified range? Do you have a Bus
or Self powered setup?
Compare the peak current consumption of EVA-8M / EVA-M8 series GNSS modules with the
specification of your power supply.
GNSS receivers require a stable power supply. Avoid series resistance in your power supply line
(the line to VCC) to minimize the voltage ripple on VCC.
Backup battery
For achieving a minimal Time To First Fix (TTFF) after a power down (warm starts, hot starts),
make sure to connect a backup battery to V_BCKP, and use an RTC. If not used, make sure
V_BCKP is connected to VCC_IO.
Antenna/ RF input
The total noise figure including external LNA (or the LNA in the active antenna) should be around
1 dB.
With the EVA-8M / EVA-M8 series GNSS module, an external LNA is mandatory if no active
antenna is used to achieve the performance values as written in the
EVA-M8 Data Sheet [1] and
the
EVA-8M Data Sheet [2] .
Make sure the antenna is not placed close to noisy parts of the circuitry and not facing noisy
parts. (e.g. micro-controller, display, etc.)
To optimize performance in environments with out-band jamming/interference sources, use an
additional SAW filter.
☞For more information dealing with interference issues see the GPS Antenna Application Note [4]
Schematic
Inner pins of the package must all be connected to GND.
2.8.2 Schematic design-in for EVA-8M / EVA-M8 series GNSS modules
For a minimal design with the EVA-8M / EVA-M8 series GNSS modules, the following functions and
pins need to be considered:
•Connect the power supply to VCC, VCC_IO and V_BCKP.

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•VDD_USB: Connect the USB power supply to a LDO before feeding it to VDD_USB and VCC or
connect it to GND if USB is not used.
•Ensure an optimal ground connection to all ground pins of the EVA-8M / EVA-M8 series GNSS
modules.
•Choose the required serial communication interfaces (UART, USB, SPI or DDC) and connect the
appropriate pins to your application
•If you need hot or warm start in your application, connect a Backup Battery to V_BCKP and add
RTC circuit.
•If antenna bias is required, see Appendix A.4.
2.9 Pin description
Pin # Name I/O Description Remark
1 RF_IN I RF Input Add external LNA and SAW if no active antenna
used.
2 GND I Ground Outer ground pin
3 Reserved I/O Reserved Do not connect. Must be left open!
4 Reserved I/O Reserved Do not connect. Must be left open!
5 USB_DM I/O USB data Leave open if not used.
6 USB_DP I/O USB data Leave open if not used.
7 VDD_USB I USB Interface power Connect to GND if not used.
8 RTC_O O RTC Output Leave open if no RTC Crystal attached.
9 RTC_I I RTC Input Connect to GND if no RTC Crystal attached.
10 Reserved I/O Reserved Do not connect. Must be left open!
11 Reserved I/O Reserved Do not connect. Must be left open!
12 PIO14 / ANT_DET I Antenna detection Leave open if not used.
13 PIO13 / EXTINT I External interrupt Leave open if not used.
14 RESET_N I System reset See section 2.7.
15 RXD / SPI MOSI I Serial interface See section 2.2.
16 TXD / SPI MISO O Serial interface See section 2.2.
17 Reserved I/O Reserved Do not connect. Must be left open!
18 GND I Ground Outer ground pin
19 VCC I Main supply See section 2.1.
20 VCC_IO I I/O Supply See section 2.1.
21 V_BCKP I Backup supply See section 2.1.
22 SQI_D0 I/O Data line 0 to external SQI flash
memory or reserved configuration pin.
Leave open if not used.
23 SQI_CLK I/O Clock for external SQI flash memory or
configuration pin.
Leave open if not used.
24 SQI_D2 I/O Data line 2 to external SQI flash
memory or reserved configuration pin.
Leave open if not used.
25 SQI_D1 I/O Data line 1 to external SQI flash
memory or reserved configuration pin.
Leave open if not used.
26 SQI_CS_N I/O Chip select for external SQI flash
memory or configuration enable pin.
Leave open if not used.
27 SQI_D3 I/O Data line 3 to external SQI flash
memory or reserved configuration pin.
Leave open if not used.
28 Reserved I/O Reserved Do not connect. Must be left open!
29 SCL / SPI CLK I Serial interface See section 2.2.
30 SDA / SPI CS_N I/O Serial interface See section 2.2.

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31 TIMEPULSE O Time pulse output Leave open if not used.
32 D_SEL I Interface selector See section 2.2.
33 SAFEBOOT_N I Used for programming the SQI flash
memory and testing purposes.
Leave open if not used.
34 ANT_OK I Antenna status Leave open if not used.
35 ANT_OFF O Antenna control Leave open if not used.
36 Reserved I/O Reserved Do not connect. Must be left open!
37 GND I Ground Inner ground pin
38 GND I Ground Inner ground pin
39 GND I Ground Inner ground pin
40 GND I Ground Inner ground pin
41 GND I Ground Inner ground pin
42 GND I Ground Inner ground pin
43 GND I Ground Inner ground pin
Table 5: EVA-8M / EVA-M8 series GNSS modules pin description
2.9.1 Pin name changes
Selected EVA-M8M pin names have been updated to agree with a common naming convention across
u-blox modules. The pins have not changed their operation and are the same physical hardware but
with updated names. The table below lists those pins along with their old and new names.
No Previous Name New name
7 V_USB VDD_USB
15 RX / MOSI RXD / SPI MOSI
16 TX / MISO TXD / SPI MISO
26 SQI_CS SQI_CS_N
29 SCL / SCK SCL / SPI CLK
30 SDA / CS_N SDA / SPI CS_N
Table 6: EVA-M8M pin name changes
☞For more information about pin assignment see the EVA-M8 Data Sheet [1] and the EVA-8M Data
Sheet
[2]
2.10 Layout design-in checklist
Follow this checklist for the layout design to get an optimal GNSS performance.
Layout optimizations (Section 2.11)
Is the EVA-8M / EVA-M8 module placed according to the recommendation in section 2.11.3?
Is the grounding concept optimal?
Has the 50 Ωline from antenna to module (micro strip / coplanar waveguide) been kept as short
as possible?
Assure low serial resistance in VCC power supply line (choose a line width > 400 um).
Keep power supply line as short as possible.
Design a GND guard ring around the optional RTC crystal lines and GND below the RTC circuit.
Add a ground plane underneath the GNSS module to reduce interference. This is especially
important for the RF input line.
For improved shielding, add as many vias as possible around the micro strip/coplanar waveguide,
around the serial communication lines, underneath the GNSS module, etc.