Ublox ANNA-B4 Series Quick setup guide

UBX-21000517 - R03
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ANNA-B4 series
Stand-alone Bluetooth 5.1 low energy modules
System integration manual
0
3
Abstract
This manual provides a functional overview combined with best-practice design guidelines for
integrating ANNA-B4 stand-alone Bluetooth® 5.1 low energy modules in customer applications.
ANNA-B402 provides an open CPU architecture with a powerful MCU for customer applications,
while ANNA-B412 is delivered with pre-flashed u-connectXpress software. Targeted towards
hardware and software application engineers, the document describes the hardware design-in,
software, component handling, regulatory compliance, and testing of the module. It also includes list
of approved external antennas for use with the module.

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Document information
Title
ANNA-B4 series
Subtitle
Stand-alone Bluetooth 5.1 low energy modules
Document type
System integration manual
Document number
UBX-21000517
Revision and date
R03
28-Jan-2022
Disclosure restriction
C1-Public
Document status explanation
Draft
For functional testing. Revised and supplementary data will be published later.
Objective Specification
Target values. Revised and supplementary data will be published later.
Advance Information
Data based on early testing. Revised and supplementary data will be published later.
Early Production Information
Data from product verification. Revised and supplementary data may be published later.
Production Information
Document contains the final product specification.
This document applies to the following products:
Product name
ANNA-B412
ANNA-B402
☞For information about the related hardware, software, and status of listed product types, see also
the respective data sheets [5] [6].
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, including 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
1Functional description .........................................................................................................................6
1.1 Overview........................................................................................................................................................6
1.2 Example applications .................................................................................................................................6
1.3 Product features .........................................................................................................................................7
1.4 Block diagrams ............................................................................................................................................8
1.5 Product description ....................................................................................................................................9
ANNA-B4 ..............................................................................................................................................9
1.6 Hardware options........................................................................................................................................9
1.7 Software options......................................................................................................................................... 9
Open CPU............................................................................................................................................10
u-connectXpress software .............................................................................................................11
1.8 Pin configurations and functions ..........................................................................................................11
2System function interfaces ............................................................................................................ 12
2.1 Main supply input......................................................................................................................................12
Digital I/O interfaces reference voltage (VCC_IO) ......................................................................12
2.2 Antenna interface .....................................................................................................................................12
ANNA-B4 integrated antenna .......................................................................................................13
Antenna connected to the antenna pin .......................................................................................13
2.3 Module reset ..............................................................................................................................................13
2.4 Internal temperature sensor...................................................................................................................13
2.5 Low power clock ........................................................................................................................................14
Internal oscillator ..............................................................................................................................14
External crystal ................................................................................................................................14
External clock source, TCXO...........................................................................................................15
Selecting clock source .....................................................................................................................15
2.6 Serial interfaces ........................................................................................................................................16
Universal asynchronous serial interface (UART) .......................................................................16
Serial peripheral interface (SPI) .....................................................................................................17
I2C interface (open CPU only).........................................................................................................17
2.7 GPIO pins.....................................................................................................................................................17
2.8 NFC interface.............................................................................................................................................18
Battery protection ............................................................................................................................19
2.9 Debug interface .........................................................................................................................................19
Thermal guidelines ...........................................................................................................................19
2.10 Reserved pins (RSVD) ..............................................................................................................................19
2.11 ANNA-B1 to ANNA-B4 migration ..........................................................................................................20
3Design-in................................................................................................................................................ 22
3.1 Overview......................................................................................................................................................22

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3.2 Antenna integration guidelines..............................................................................................................22
3.3 Antenna connected through the RF pin...............................................................................................23
RF transmission line design ...........................................................................................................24
RF connector design ........................................................................................................................25
3.4 Supply interfaces ......................................................................................................................................26
VCC application circuits ..................................................................................................................26
3.5GND pins .....................................................................................................................................................27
3.6 General layout guidelines ........................................................................................................................27
Considerations for schematic design and PCB floor-planning ...............................................27
Layout and manufacturing.............................................................................................................27
ESD guidelines...................................................................................................................................28
3.7 Design-in checklists .................................................................................................................................29
Schematic checklist.........................................................................................................................29
Layout checklist................................................................................................................................29
4Open CPU software............................................................................................................................ 30
4.1 Zephyr .........................................................................................................................................................30
Getting started with Zephyr on the ANNA-B4 module.............................................................30
Board configuration in Zephyr .......................................................................................................30
Building for ANNA-B402 EVK on the Zephyr command-line...................................................30
4.2 Nordic nRF5 SDK ......................................................................................................................................30
Getting started with the Nordic nRF5 SDK.................................................................................31
Create a custom board support file for Nordic nRF5 SDK .......................................................31
Adding a board configuration to your project .............................................................................33
4.3 Definition of Low Frequency clock source ...........................................................................................34
4.4 Bluetooth device (MAC) address and other production data ..........................................................34
4.5 Flashing open CPU software ..................................................................................................................35
Flashing over the SWD interface...................................................................................................35
Flashing over the UART interface .................................................................................................35
5u-connectXpress software .............................................................................................................. 38
5.1 Flashing ANNA-B412 u-connectXpress software .............................................................................38
Updating over UART.........................................................................................................................38
5.2 Low frequency clock and autosense .....................................................................................................45
6Handling and soldering ..................................................................................................................... 47
6.1 ESD handling precautions.......................................................................................................................47
6.2 Packaging, shipping, storage, and moisture preconditioning .........................................................47
6.3 Soldering .....................................................................................................................................................47
Reflow soldering process ................................................................................................................48
Cleaning ..............................................................................................................................................49
Potting and conformal coating ......................................................................................................49
Other remarks ...................................................................................................................................49
7Qualifications and approvals .......................................................................................................... 50
7.1Country approvals.....................................................................................................................................50

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7.2 European Union regulatory compliance ...............................................................................................50
Radio Equipment Directive (RED) 2014/53/EU ..........................................................................50
Compliance with the RoHS directive ............................................................................................50
7.3 FCC and IC compliance ............................................................................................................................50
FCC compliance..............................................................................................................................................51
RF-exposure statement ..................................................................................................................52
End product user manual instructions.........................................................................................52
End product labeling requirements ..............................................................................................53
FCC and IC IDs ...................................................................................................................................54
End product compliance..................................................................................................................54
7.4 Japan radio equipment compliance......................................................................................................54
Compliance statement....................................................................................................................54
End product labelling requirement................................................................................................55
End product user manual requirement ........................................................................................55
7.5 NCC Taiwan compliance ..........................................................................................................................55
Taiwan NCC Warning Statement..................................................................................................55
Labeling requirements for end product .......................................................................................55
7.6 KCC South Korea compliance.................................................................................................................56
7.7 Brazil compliance ......................................................................................................................................56
7.8 Australia and New Zealand regulatory compliance ...........................................................................56
7.9 South Africa regulatory compliance .....................................................................................................57
7.10 Bluetooth qualification.............................................................................................................................57
8Pre-approved antennas list............................................................................................................. 58
8.1 Approved antennas ..................................................................................................................................58
9Product testing ................................................................................................................................... 60
9.1 u-blox in-line production testing ............................................................................................................60
9.2 OEM manufacturer production test .....................................................................................................61
“Go/No go” tests for integrated devices ......................................................................................61
Appendix ....................................................................................................................................................... 62
AGlossary ................................................................................................................................................. 62
BAntenna reference designs ............................................................................................................. 64
B.1 Internal antenna reference design with module at PCB corner.......................................................64
B.2 Internal antenna reference design with module along PCB edge ...................................................66
B.3 Reference design for external antennas (U.FL connector) ..............................................................67
B.4 Examples of application ground plane miniaturizations ..................................................................68
B.4.1 Example application 1......................................................................................................................69
B.4.2 Example application 2......................................................................................................................71
Related documentation ........................................................................................................................... 72
Revision history.......................................................................................................................................... 73
Contact.......................................................................................................................................................... 74

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1Functional description
1.1 Overview
The ANNA-B4 series are small, stand-alone Bluetooth 5.1 Low Energy (LE) wireless module that are
particularly suited for harsh professional environments.
Based on the Nordic Semiconductor nRF52833 chip that includes an integrated RF core and powerful
Arm® Cortex®-M4 with FPU processor, ANNA-B4 operates in all Bluetooth 5.1 modes –as well as
802.15.4 (Thread and Zigbee) and Nordic proprietary modes (ANNA-B402 only).
Featuring Angle of Arrival (AoA) and Angle of Departure (AoD) transceivers, ANNA-B402 supports the
Bluetooth 5.1 Direction Finding service. The service can for example be used for indoor positioning,
wayfinding, and asset tracking.
ANNA-B4 modules need only a single supply voltage in the range of 1.7–3.6 V and, as the supply
voltage level can also be used as the I/O reference level, can be easily integrated into simple, single
voltage rail systems. The broad supply voltage range makes ANNA-B4 particularly useful in battery
powered systems. To use the USB interface VBUS 5 V supply is required.
With the same physical size and mechanical design as the ANNA-B112 module, ANNA-B4 offers a
natural upgrade path for existing ANNA-B1 applications. Four additional pins on ANNA-B4, included
to increase the number of supported GPIOs module, can be conveniently accommodated within a
common module footprint. ANNA-B4 also extends the operating temperature range to +105 °C,
beyond the +85 °C specified for ANNA-B1.
Table 1 describes the various models in the ANNA-B4 series.
Model
Description
ANNA-B402
ANNA-B4 open CPU module, that enables customer applications to run on the built-in Arm®
Cortex®-M4 with FPU. Equipped with an integrated chip antenna but can also be used with an
external antenna via the antenna pin.
ANNA-B412
ANNA-B4 module with pre-flashed u-connectXpress software application. Equipped with an
integrated chip antenna but can also be used with an external antenna via the antenna pin.
Table 1: ANNA-B4 series models
See also the ANNA-B402 and ANNA-B412 data sheets [5] [6] and ANNA-B402 and ANNA-B412
product summaries [3] [4].
1.2 Example applications
The ANNA-B4 modules are applicable for a wide range of different applications:
•Industrial automation
•Smart buildings and cities
•Low power sensors
•Wireless-connected and configurable equipment
•Point-of-sales
•Health devices
•Real-time Location, RTLS
•Indoor positioning
•Asset tracking
•Wearables

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1.3 Product features
Figure 1: ANNA-B4 series main features summary

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1.4 Block diagrams
A block diagram of the ANNA-B4x2 module is shown in Figure 2.
☞Not all interfaces are supported by the u-connectXpress software in ANNA-B412 variants.
For information about the interfaces supported specifically in ANNA-B412, see also the
ANNA-B412 data sheet [6].
Figure 2: ANNA-B4x2 block diagram
The ANNA-B4 System in Package (SiP) module has an integrated antenna. The “RF pin”can either be
connected directly to the adjacent “Antenna pin”to use the internal antenna. Otherwise, it can be
routed to an external antenna or antenna connector. When using the internal antenna, a counterpoise
trace must be routed on the main PCB and connected to “Antenna PCB” pin.
To achieve the lowest possible power consumption in stand-by mode ANNA-B4 has the possibility to
connect an optional external 32.768 kHz LPO crystal or oscillator.
VCC_IO (1.7 –3.6 V)
DC/DC and LDO regulators
512 kB flash
Bluetooth LE
baseband
IO buffers
Arm® Cortex®-M4
with FPU
PLL
VCC (1.7 –3.6 V)
32 MHz
Reset
UART
SPI
GPIO
1.3 V
System
power
I2C
PWM
I2S
ADC and
comparator
Analog
Passive NFC tag
NFC
128 kB
RAM
PLL
32.768 kHz
RTC, timers
and counters
RF
Nordic nRF52833
USB device
USB 2.0
QDEC
PDM
Antenna
Antenna PCB
Antenna pin
RF pin
ANNA-B4x2

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1.5 Product description
ANNA-B4
Item
ANNA-B402 / ANNA-B412
Bluetooth version
5.1
Band support
2.4 GHz, 40 channels
Typical conducted output power
+8 dBm
Max radiated output power with internal antenna (EIRP)
+9 dBm
Max radiated output power with external antenna (EIRP)
+13 dBm (pending certification)
RX sensitivity (conducted)
-94 dBm
RX sensitivity, long range mode (conducted)
-103 dBm
Supported 2.4 GHz radio modes
Bluetooth Low Energy
IEEE 802.15.4 (ANNA-B402 only)
Proprietary 2.4 GHz modes (ANNA-B402 only)
Supported Bluetooth LE data rates
1 Mbps
2 Mbps
500 kbps
125 kbps
Module size
6.5 x 6.5 x 1.2 mm
Table 2: ANNA-B4 series characteristics summary
For more information about each module variant, see also the ANNA-B402 [5] and ANNA-B412 [6]
data sheets.
1.6 Hardware options
ANNA-B402 and ANNA-B412 modules have identical hardware architecture and design. Both module
variants are based on the Nordic Semiconductor nRF52833 System on Chip (SoC).
1.7 Software options
ANNA-B4 modules are integrated with an Arm® Cortex®-M4 application processor with FPU, 512 kB
flash memory and 128 kB RAM.
The structure of any software running on either ANNA-B4 module variant includes the following
components:
•Radio stack
•Bootloader (optional)
•Application
The fundamental differences in the software implantation of the two module variants include:
•ANNA-B402 modules host the customer application and optional bootloader software, developed
using the Nordic SDK, in an open-CPU configuration on the module. See also Open CPU.
•ANNA-B412 modules are pre-flashed with a secure bootloader and u-connectXpress software that
interfaces through an AT command interpreter to control customer application software running
on host MCUs. See also u-connectXpress software.
•Both module variants include the Nordic S140 SoftDevice Bluetooth Low Energy protocol stack
that supports GATT server and client, central and peripheral roles, and multidrop connections.

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Figure 3 shows the software architecture and implementation of software components for
ANNA-B402 and ANNA-B412 modules.
Figure 3: ANNA-B4 software structure
Open CPU
The open CPU architecture of ANNA-B402 series modules allows module integrators to build their
own applications. Table 3 describes the possible connectivity and application support for
recommended Nordic SDK environments in ANNA-B40 hardware. See also Open CPU software.
Feature
Support
Development environment
Nordic SDK (including Bluetooth Mesh, HomeKit, AirFuel, IoT, Thread, Zigbee)
HW interfaces
2 x UART
4 x SPI
33 x GPIO pins
8 x ADC channels
1 x USB
2 x I2C
1 x I2S
4 x PWM
1 x QDEC
Security
Secure boot ready
Secure Simple Pairing
128-bit AES encryption
Bluetooth low energy secure connections
Table 3: Open CPU software support
See also Open CPU software.

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u-connectXpress software
ANNA-B412 modules are pre-flashed with u-connectXpress and bootloader software, which
interfaces through an AT command interpreter to control customer application software running on
host MCUs. Table 4 describes the feature support in the u-connectXpress software.
Feature
Support
Bluetooth
u-blox Low Energy Serial Port Service (SPS)
GATT server and client using AT commands
Beacons
1 + 2 Mbit/s modulation
125 Kbit/s modulation long range functionality
Advertising extensions
Configuration over air
Wireless transmission of AT commands to control the module
Extended Data Mode™
For simultaneous AT commands and data, and multiple simultaneous data streams
HW interfaces
2 x UART, 19 x GPIO
Configuration
AT commands
Support tools
s-center
Operating modes
Central role (7 simultaneous links)
Peripheral role (6 simultaneous links)
Simultaneous central and peripheral roles
(8 in total, where max 4 as peripheral and max 7 as central)
LE 1M PHY
LE 2M PHY
LE CODED PHY
Advertising extensions
LE data length extension
Bluetooth mesh (Available on request. Contact us.)
Direction finding (AoA / AoD) (Available on request. Contact us.)
Security
Secure boot
Secure Simple Pairing
128-bit AES encryption
Bluetooth low energy secure connections
Throughput over UART
780 Kbit/s
Table 4: u-connectXpress software support
See also u-connectXpress software.
1.8 Pin configurations and functions
For information about pin configuration and functions, see the ANNA-B402 and ANNA-B412 data
sheets [5] [6].

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2System function interfaces
2.1 Main supply input
The power for ANNA-B4 modules is provided through the VCC pins. ANNA-B4 uses an integrated
DC/DC converter to transform the supply voltage presented at the VCC pin into a stable system core
voltage. This makes ANNA-B4 modules compatible for use in battery-powered designs.
The VCC supply can be taken from any of the following sources:
•Switched Mode Power Supply (SMPS)
•Low Drop Out (LDO) regulator
•Battery
When using ANNA-B4 with a battery, it is important that the chosen battery can handle the peak
power of the module. In case of battery supply, consider adding extra capacitance on the supply line
to avoid capacity degradation. For information about voltage supply requirement and current
consumption, see also the respective ANNA-B402 [5] and ANNA-B412 data sheets [6].
Digital I/O interfaces reference voltage (VCC_IO)
On ANNA-B4 modules, the I/O voltage level is the same as the supply voltage and VCC_IO is internally
connected to the supply input VCC.
When using ANNA-B4 with a battery, the I/O voltage level varies with battery output voltage. The
battery voltage depends on the battery “state of charge”. Level shifters might be needed to stabilize
the voltage –depending on the I/O voltage of the host system and interfacing components.
2.2 Antenna interface
ANNA-B4 is equipped both with an integrated chip antenna and an RF pin. The integrated chip
antenna makes ANNA-B4 suitable for a minimum sized application product. The RF pin enables use
of other antenna types. This could be either an antenna placed on the main PCB or an external
antenna.
ANNA-B4 supports the following antenna types:
•Integrated antenna included in ANNA-B4 SiP. The integrated antenna requires an external
counterpoise trace on the main PCB.
•Integrated antenna on the main PCB. Typically, a SMD antenna mounted on the main PCB, which
is connected to the ANNA-B4 RF pin through a transmission line.
•External Antenna. Typically, a dipole antenna connected to the ANNA-B4 RF pin through a coaxial
cable and U.FL connector on the main PCB.
Table 5 describes how the related pins shall be connected for each antenna solution
Pin
External antenna, or
integrated antenna on
main PCB
ANNA-B4 integrated antenna.
ANNA-B4 placed in the corner of
the main PCB
ANNA-B4 integrated antenna.
ANNA-B4 placed along the side of
the main PCB
Pin 1 –ANT_PCB
GND*
GND pattern
NC
Pin 2 –ANT_GND
GND
NC
GND pattern
Pin 3 –ANT_GND
GND
NC
GND pattern
Pin 5 –ANT_INT
GND*
Connect to pin 6 –ANT
Connect to pin 6 –ANT
Pin 6 - ANT
Connect to antenna or
antenna connector
Connect to pin 5 –ANT_INT
Connect to pin 5 –ANT_INT
*Connect to GND for better layout, not critical for function
Table 5: ANNA-B4 Antenna options

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⚠When integrating the u-blox reference design into an end-product, the application designer is
solely responsible for any unintentional emission levels produced by the end-product.
ANNA-B4 integrated antenna
☞ANNA-B4 is pre-certified with the integrated antenna. To take advantage of this certification, the
module must be integrated in strict accordance with the ANNA-B4 Antenna reference design.
When including ANNA-B4 with an integrated antenna into the application design, the reference
design must be followed precisely to reach full radiated performance. The reference design defines
where to position ANNA on the main PCB and describes how to route the counterpoise antenna trace.
Although an integrated antenna can be placed in either the corner or along the edge of the application
board, a corner location offers slightly better antenna performance.
Antenna connected to the antenna pin
This section describes the integration of any antenna connected to the RF pin, external antenna, or
integrated antenna on the main PCB.
ANNA-B4 is equipped with an RF pin for connection of an antenna when the antenna integrated in
ANNA-B4 is not the preferred antenna option. The RF pin has a nominal characteristic impedance of
50 Ωand must be connected to the antenna through a 50 Ωtransmission to reach full performance.
In this way, the transmission of incoming and outgoing radio frequency (RF) signals is optimized in
the 2.4 GHz frequency band.
Choose an antenna with optimal radiating characteristics for the best electrical performance and
overall module functionality. Use either an internal antenna integrated on the main PCB or an external
antenna connected to the main PCB through a 50 Ωconnector.
When using an external antenna, the PCB-to-RF cable transition must be implemented using either a
suitable 50 Ωconnector or an RF-signal solder pad (including GND) that is optimized for 50 Ω
characteristic impedance.
2.2.2.1 Approved antenna pin designs
ANNA-B4 module is pre-certified together with external antennas. The external antenna is in this
design connected to the RF pin via a U.FL connector. The connection between the RF pin and U.FL
connector is routed with a 50 ohm transmission line. It is advised to implement this reference design
in the application product to save costs and time during the certification process when implementing
an external antenna. See also the Pre-approved antennas list.
This reference design is described in Appendix B.3.
The module may be integrated with other antennas. In which case, the OEM installer must certify his
design with respective regulatory agencies.
2.3 Module reset
ANNA-B4 series is reset by applying a low level on the RESET_N input pin, which is normally set high
with an internal pull-up. A low logic level on this pin initiates an “external” or “hardware” reset of the
module. The prevailing parameter settings at the time of the reset are not saved in the non-volatile
memory of the module and a proper network detach is not performed.
2.4 Internal temperature sensor
The radio chip in the ANNA-B4 series module contains a temperature sensor that is primarily used for
over-temperature and under-temperature shutdown.

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⚠As the temperature sensor is embedded in the radio chip, any intensive processing can cause extra
heat and impact the measurement accuracy. An external sensor is required if more accurate
monitoring of the surrounding area is necessary.
2.5 Low power clock
ANNA-B4 uses a 32.768 kHz low power clock to enable different power modes: active, sleep, and
standby. For further information about power modes, see also the ANNA-B412 data sheet [6].
The clock can be generated from either of the following internal or external clock sources:
•Internal oscillator
•External crystal
•External clock source, TCXO
The u-connectXpress software automatically senses the clock input and uses the source from the
external crystal –if one is available. Otherwise, the software uses the source from the internal
oscillator. This automatic sense functionality adds some additional time during startup (~1 s).
To get the lowest possible current consumption of the ANNA-B4 module in sleep mode, an external
crystal or external clock source is needed. If an external crystal or external clock source is not
connected, the internal oscillator must be used instead. The lower accuracy of the internal oscillator
means that the module must perform a calibration at specific intervals, which causes the current
consumption to increase in sleep mode.
For further information about the different hardware options for the low-power clock source and the
implications those choices have on both the cost and performance of the ANNA-B4 module, see also
Internal oscillator, External crystal, External clock source, TCXO, and Selecting clock source.
☞For practical guidance on how to configure the oscillator on nRF5 open CPU modules, see the
related application note [8].
☞An external crystal is also required by some third-party software, like Wirepas Massive.
Internal oscillator
When using the internal oscillator, clock pins XL_1 and XL_2 should be connected to ground, as shown
in Figure 4.
⚠To ensure +/-250 ppm clock stability, open-CPU application software must be configured to check
the calibration of the internal oscillator at least once every 8 seconds. This configuration is fixed
in u-connectXpress software.
☞The use of an internal oscillator with ANNA-B4 can minimize the Bill of Materials (BOM) and reduce
the associated production costs of the end product. But, it can also increase power consumption
in standby mode.
External crystal
ANNA-B4 has two input pins for connecting an external crystal as the source for the low-power clock.
The use of an external crystal allows ANNA-B4 to run with the lowest overall power consumption.

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Figure 4 shows the low-power clock components used on the EVK-ANNA-B4 evaluation board.
Figure 4: Connecting ANNA-B412 to an external crystal oscillator
Table 6: Components used on the EVK-ANNA-B4 EVK evaluation board
External clock source, TCXO
An external clock can be supplied from various sources, including a temperature-compensated crystal
oscillator (TCXO) or host CPU. The clock signal can be either low-swing or full-swing.
The electrical parameters for a suitable low-swing clock are described in Table 7.
Pin name
Parameter
Min
Typ
Max
Unit
Remarks
XL1
Input characteristic:
Peak to Peak amplitude
200
1000
mV
Input signal must not swing outside
supply rails.
XL2
-
-
-
-
Connect to GND
Table 7: Electrical parameters for a low-swing clock
The electrical parameters for a suitable full-swing clock are described in Table 8.
Pin name
Parameter
Min
Typ
Max
Unit
Remarks
XL1
Input characteristic:
Low-level input
0
0.3*VCC
V
Input characteristic:
high-level input
0.7*VCC
VCC
V
XL2
-
-
-
-
-
Connect to GND or leave unconnected
Table 8: Electrical parameters for a full-swing clock
Selecting clock source
☞With reference to the electrical parameters described in Table 8, note that the choice of clock
source is invariably a tradeoff between the current consumption and BOM count of the application
design. When using an internal oscillator, the expected increase in current consumption is
dependent on the software settings and the surrounding application environment.
Component
Value
Note
Crystal oscillator
32.768 kHz (20 ppm)
EPSON FC-12M used on ANNA-B4 EVK
Capacitors
22 pF

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Depending on the software settings, the internal oscillator itself adds ~400 nA to the current
consumption and the calibration of the oscillator adds another ~1 µA. The standby current of
ANNA-B4 then increases from 2.2 µA to 3.6 µA, which is an increase of ~60%. For information about
the possible settings using open CPU software, see also the application note RC oscillator
configuration for nRF5 open CPU modules [8].
☞Low Frequency Clock settings are fixed for use with u-connectXpress software.
For applications where only the active mode is used, and the module never or rarely is in standby, the
increase of current is negligible.
If the application is expected to be in standby for longer periods of time and it is powered from a
battery, it might be worth adding an external crystal.
Table 9 shows the average current consumption for a beacon advertising at different intervals, when
using an external crystal oscillator versus when using the internal oscillator. The use case shown here
is based on an advertisement event (4.7 ms) that is broadcast with +4 dBm output power, 31 bytes,
and 3.3 V payload.
Table 9: Average current consumption with/without external low power crystal (theoretical calculations)
2.6 Serial interfaces
The pin mapping of the supported interfaces is dependent on whether ANNA-B4 is used with
u-connectXpress software or an open CPU based application. See also the ANNA-B402 [5] and
ANNA-B412 [6] data sheets.
Universal asynchronous serial interface (UART)
ANNA-B4 series modules provide a Universal Asynchronous Serial Interface (UART) for data
communication.
The following UART signals are available:
•Data lines (RXD as input, TXD as output)
•Hardware flow control lines (CTS as input, RTS as output)
•DSR and DTRare used to set and indicate system modes
The UART can be used as a 4-wire UART with hardware flow control or 2-wire UART with only TXD
and RXD. In 2-wire mode, CTS should be connected to GND on the ANNA-B4 module.
The bootloader delivered with the product, either u-connectXpress bootloader or the Nordic DFU
bootloader for open CPU modules, can be used to upgrade the software over the UART interface.
See also Flashing over the UART interface and Flashing ANNA-B412 u-connectXpress software.
The u-connectXpress software adds the DSR and DTR pins to the UART interface. These pins are not
used as originally intended but are used instead to control the state of the ANNA-B412 module.
Depending on the configuration of u-connectXpress, the DSR can be used to:
•Enter command mode
•Disconnect and/or toggle connectable status
•Enable/disable the rest of the UART interface
•Enter/wake up from the sleep mode
Advertise interval
External crystal oscillator
Internal oscillator
Increase in current
1 s
18 µA
19.5 µA
8 %
10 s
3.8 µA
5.2 µA
37 %
60 s
2.4 µA
3.9 µA
63 %

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For more information about the UART interface characteristics, see also the ANNA-B402 and
ANNA-B412 data sheet [5] and [6].
Interface
Default configuration
COM port
115200 baud, 8 data bits, no parity, 1 stop bit, hardware flow control
Table 10: Default settings for the COM port while using the u-connectXpress software
It is advisable to make the UART available as either test points or as available through a connected
header for software upgrade.
The IO level of the UART follows the VCC voltage and can subsequently in the range of 1.8–3.6 V. If
you are connecting the ANNA-B4 module to a host with a different voltage on the UART interface, a
level shifter should be used.
Serial peripheral interface (SPI)
The ANNA-B4 series supports up to four serial peripheral interfaces that can operate in both master
and slave modes with a maximum serial clock frequency of 8 MHz in both these modes.
The SPI interfaces use the four following signals:
•SCLK
•MOSI
•MISO
•CS
When using the SPI interface in master mode, it is possible to use GPIOs as additional Chip Select (CS)
signals to allow addressing of multiple slaves.
I2C interface (open CPU only)
The Inter-Integrated Circuit (I2C) interfaces can be used to transfer or receive data on a 2-wire bus
network. The ANNA-B4 series contains up to two I2C bus interfaces and can operate as both master
and slave using both standard (100 kbps) and fast (400 kbps) transmission speeds. The interface
uses the SCL signal to clock instructions and data on the SDL signal.
External pull up resistors are required for the I2C interface. The value of the pull-up resistor should be
selected depending on the speed and capacitance of the bus.
2.7 GPIO pins
ANNA-B4 series modules can provide up to 33 pins, which can be configured as general-purpose input
or output. Eight GPIO pins are capable of handling analog functionality. All pins are capable of handling
interrupt.
Function
Description
Default ANNA-B4 pin
Configurable GPIOs
General purpose input
Digital input with configurable edge detection and
interrupt generation.
Any
General purpose
output
Digital output with configurable drive strength, pull-
up, pull-down, open-source, open-drain and/or slew
rate.
Any
Pin disabled
Pin is disconnected from input buffers and output
drivers.
All*
Any
Timer/ counter
High precision time measurement between two
pulses/ Pulse counting with interrupt/event
generation.
Any
Interrupt/ Event
trigger
Interrupt/event trigger to the software application/
Wake up event.
Any

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Function
Description
Default ANNA-B4 pin
Configurable GPIOs
ADC input
8/10/12-bit analog to digital converter
Any analog
Analog comparator
input
Compare two voltages, capable of generating wake-
up events and interrupts
Any analog
PWM output
Output complex pulse width modulation waveforms
Any
Connection status
indication
Indicates if a Bluetooth LE connection is maintained
BLUE**
Any
* = If left unconfigured ** = If using u-connectXpress software. For pin number, see also the ANNA-B412 data sheet [6].
Table 11: GPIO custom functions configuration
2.8 NFC interface
Figure 5 shows some important aspects of the NFC antenna design, where:
•The NFC antenna coil must be connected differentially between the NFC1 and NFC2 pins of the
device.
•Two external capacitors should be used to tune the resonance of the antenna circuit to 13.56 MHz.
Figure 5: NFC antenna design
The value of the required tuning capacitors (Ctune) is calculated with the two equations shown below.
An antenna inductance of Lant = 2 μH gives tuning capacitors in the range of 130 pF on each pin. For
good performance, match the total capacitance on NFC1 and NFC2.

󰆒
󰇛  󰇜 
󰆒
    
 
󰇛  󰇜   
⚠As the pins for the NFC interface in ANNA-B402 series modules can be used as normal GPIOs, it is
important that all NFC pins are correctly configured in the software. Connecting an NFC antenna
to pins that are configured for GPIO might damage the module. In ANNA-B412 series modules,
NFC pins are always set to "NFC mode".

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ANNA-B4 modules have been tested with a 3 x 3 cm PCB trace antenna, so it is advisable to keep these
measurements as closely as possible to antenna design. You can still use a smaller or larger antenna
if it is tuned to resonate at 13.56 MHz. To comply with European regulatory demands, the NFC
antenna must be placed in such a way that the space between the ANNA-B4 module and the remote
NFC transmitter is always within three meters during transmission.
Battery protection
If the antenna is exposed to a strong NFC field, parasitic diodes and unintended ESD structures can
cause the current to flow in the opposite direction of the supply.
If the battery used does not tolerate a return current, protect the battery with a series diode placed
between the battery and the device.
2.9 Debug interface
ANNA-B402 modules support Serial Wire debug (SWD) and Serial Wire Viewer, but not JTAG debug.
When designing your application with the ANNA-B402, the SWD interface (pins SWDCLK and
SWDIO) to the module should ideally be made available in the application design.
So that ANNA-B402 can be flashed over the UART or SWD interface, the module is preloaded with
bootloader software that is without security. A debug connector to the module is also useful during
the software development.
For security reasons, the debug interface should be disabled to prevent the upload or download of
insecure software –or software that has not been validated.
Figure 6 shows the pinout of the 10-pin, 50 mil pitch connector used on the EVK-ANNA-B402. This
compact debug header can also be used on a host board design. Keep in mind that the GND and
VDD_IO references are needed for the SWD interface to work.
Figure 6: Cortex debug connector pin out for SWD
Thermal guidelines
ANNA-B4 series modules have been successfully tested from –40 °C to +105 °C. ANNA-B4 modules
are low-power devices that generate only a small amount of heat during operation. A good grounding
should nonetheless be observed for temperature relief during high ambient temperatures.
2.10 Reserved pins (RSVD)
Do not connect any reserved (RSVD) pins. The reserved pins can be allocated for future interfaces and
functionality.

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2.11 ANNA-B1 to ANNA-B4 migration
ANNA-B4 is pin compatible with ANNA-B1 and provides a simple migration path for upgrading
applications with the extra features that ANNA-B4 modules deliver, including, increased memory,
increased output power, coded physical layer (PHY), higher operating temperature range, and
u-connectXpress secure-boot software.
Figure 7 shows the footprints of the u-connectXpress ANNA-B112 and ANNA-B412 modules.
Although the pin assignments vary, the positioning of the pin are identical.
Figure 7: ANNA-B112 u-connectXpress footprint and ANNA-B412 u-connectXpress footprint
Figure 8 shows the footprints of the open CPU ANNA-B112 and ANNA-B402 modules. Although the
pin assignments vary, the positioning of the pin are identical.
A= Analog function capable pin LF = Low Frequency, low drive I/O only
Signals that are highlighted in red are locked to a specific pin, the grey pins are GND pins.
Figure 8: ANNA-B112 open CPU footprint and ANNA-B402 open CPU footprint