NXP Semiconductors i.MX RT685 User manual

i.MX RT685 Evaluation Board
NXP Semiconductors Document identifier: UM11159
User's Guide Rev. 0, March 20 2020

Contents
Chapter 1 Introduction........................................................................................... 3
Chapter 2 Board layout and settings......................................................................5
Chapter 3 Getting started.....................................................................................13
3.1 Starting a debug session using the on-board (Link2) Debug Probe........................................13
Chapter 4 On-board (Link2) debug probe............................................................15
4.1 Programming the Link2 firmware.............................................................................................15
4.2 VCOM port...............................................................................................................................16
Chapter 5 Board power........................................................................................17
5.1 Measuring MIMXRT685-EVK device supply current............................................................... 17
5.2 PMIC (PCA9420).....................................................................................................................17
Chapter 6 Board serial connections.....................................................................19
6.1 USB high-speed port............................................................................................................... 19
6.2 USART header........................................................................................................................ 19
6.3 I3C header...............................................................................................................................19
6.4 Flexcomm header....................................................................................................................19
6.5 Additional expansion header................................................................................................... 21
Chapter 7 On-board peripherals.......................................................................... 22
7.1 Audio Codec............................................................................................................................22
7.2 Audio digital amplifiers.............................................................................................................22
7.3 SD/eMMC card slot................................................................................................................. 23
7.4 Accelerometer......................................................................................................................... 23
7.5 User LEDS...............................................................................................................................23
7.6 Buttons.................................................................................................................................... 23
7.7 ISP boot config........................................................................................................................ 24
7.8 DMIC....................................................................................................................................... 25
Chapter 8 Expansion connectors.........................................................................27
8.1 PMod connector...................................................................................................................... 27
8.2 Arduino connector................................................................................................................... 27
Chapter 9 Other board features........................................................................... 30
9.1 MIMXRT685-EVK ADC references and inputs........................................................................30
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Chapter 1
Introduction
The i.MX RT685 Evaluation Board (part number MIMXRT685-EVK) is designed for customers to evaluate the i.MX RT685 MCU.
It can be used with a range of development tools, including NXP’s MCUXpresso IDE. This User Manual describes Revision E of
the board with B0 silicon.
The EVK is subject to changes in future revisions.
NOTE
Figure 1. i.MX RT685 board
The i.MX RT685 EVK includes the following features:
• i.MX RT685 Cortex-M33 core processor with Cadence Xtensa HiFi4 DSP
• Onboard, high-speed USB, Link2 debug probe with CMSIS-DAP protocol (supporting Cortex M33 debug only)
• High speed USB port with micro A/B connector for the host or device functionality
• UART, I2C and SPI port bridging from i.MX RT685 target to USB via the on-board debug probe
• Optional external debug probe connections with trace option (10 or 20 pin Cortex-M connectors, later required for trace)
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• 512 MB Macronix Octal SPI Flash operating at 1.8 V
• 4.5 MB Apmemory PSRAM
• Full size SD card slot (SDIO)
• NXP PCA9420UK PMIC
• User LEDs
• Reset and User buttons
• Arduino and PMod/Host expansion connectors
• NXP FXOS8700CQ accelerometer
• Stereo audio codec with line in/out and electret microphone
• Stereo NXP TFA9894 digital amplifiers, with option for external +5V power for higher performance speakers
• Support for up to eight off-board digital microphones via 12-pin header
• Two on-board DMICS
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Introduction
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Chapter 2
Board layout and settings
Figure 2 shows the layout of the board (top side), indicating location of the connectors and buttons.
Figure 2. i.MX RT685 EVK connectors, LEDs, buttons and headers
Table 1 provides a description of connectors, LEDs and buttons.
Table 1. Connectors, LEDs, buttons and headers
Circuit ref (Rev E) Description Default Reference
D1 Reset LED N/A Schematic
D2 Link2 boot LED N/A Schematic
D8 - D10 User LEDs. N/A User LEDS
Table continues on the next page...
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Table 1. Connectors, LEDs, buttons and headers (continued)
Circuit ref (Rev E) Description Default Reference
D11 3.3 V power on LED (LD2_OUT when
JS11 shunted)
N/A Schematic
D15 SD card power LED (JS14 shunted) N/A Schematic
J2 10-pin Cortex-M target debug
header.
N/A Schematic
J3 Audio codec line input jack N/A Schematic
J4 Audio codec line output jack N/A Schematic
J5 On board debug probe (LINK USB)
micro B USB connector
N/A Schematic
J6
External +5 V power
Micro USB connection for power to
the i.MX RT685 target and peripheral
circuitry (excluding Link2 Debug
Probe).
N/A Schematic
J7 Micro AB High speed USB
connector Device/Host.
N/A USB high-speed port
J19 Debug Trace Connector. 20-pin
Cortex-M debug connector for i.MX
RT685 target, including trace pins.
N/A Schematic
J11, J20
Screw terminal connections for
external speakers. When attaching a
speaker, ensure that the appropriate
driver settings are used in the
TFA9894 devices to avoid damage
to the speaker.
N/A Schematic
J21 Batt charger. N/A Schematic
J24
Additional +5 V power connector.
This barrel type connector may be
used to supply additional power to
the digital amplifiers, if needed. It
does not power any of the other
circuitry on the board.
N/A Schematic
J27 – J30 J27, J28, J29, J30 Arduino
expansion connectors.
N/A Arduino connector
J31
External DMIC header. Provides
access to all DMIC (PDM) clock and
data lines, along with 1.8V (default
SW2_OUT)
N/A External DMIC
J32 SD/eMMC Card socket. N/A SD/eMMC card slot
J36 PMod/Host connector. This
connector provides access to the N/A PMod connector
Table continues on the next page...
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Table 1. Connectors, LEDs, buttons and headers (continued)
Circuit ref (Rev E) Description Default Reference
SPI and I2C ports of the i.MX RT685
that are also designated for ISP
boot. This connector can be used to
work with a remote host, or as an
interface to off-the-shelf PMod
expansion boards.
J47 Flexcomm interface. N/A Flexcomm header
P1 Electret mic. N/A Schematic
SW1, SW2
User buttons. These buttons, when
pressed, pulls the connected i.MX
RT685 pin (P1_1 for SW1 and P0_10
for SW2) to ground. A 100 K ohm
pull up to VDDIO_1 is connected to
the pin.
N/A User buttons (SW1 and SW2)
SW3
Reset button. When pressed, reset
is applied to the i.MX RT685,
TFA9894 amplifiers, Octal SPI flash,
pSRAM, expansion connector
(Arduino reset, if JP14 is installed).
N/A Reset
SW4 PMIC on button. N/A PMIC-ON
SW5
Boot Config switch. ISP boot mode
selection. Switch the DIP switch for
ISP port signal to ON to pull that pin
low via a 1K ohm resistor. Switch 1
is for ISP0, 2 for ISP1 and 3 for
ISP2.
ISP0 ON
ISP1 OFF
ISP2 ON ISP boot config
U1 LPC4322. N/A Schematic
U6 Accelerometer FXOS8700CQ. N/A Accelerometer
U8 Audio CODEC. N/A Audio Codec
U12, U17 Digital Audio Amplifiers N/A Audio digital amplifiers
U18 MIMXRT685. N/A Schematic
U19 Octal SPI Flash. N/A Schematic
U20
PMIC. Programmable output voltage
regulator with four different outputs:
SW1, SW2, LDO1 and LDO2.
N/A PMIC (PCA9420)
U40, U41 On-Board DMICs. N/A On-board DMIC
U108 pSRAM N/A Schematic
Figure 3 shows location of jumpers and headers.
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Board layout and settings
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Figure 3. i.MX RT685 EVK jumpers and headers
Table 2 provides a description of jumpers and indicators.
Table 2. Indicators and jumpers
Circuit ref (Rev E) Description Default Reference
JP1
Link2 (LPC43xx) force DFU boot.
Leave this jumper open (default) for
Link2 to follow the normal boot
sequence. The Link2 will boot from
flash if image is found there. With the
flash erased the Link2 normal boot
sequence will fall through to DFU boot.
Install this jumper to force the Link2 to
DFU boot mode. Use this setting to
reprogram the Link2 internal flash with
a new image (using the LPCScrypt
utility) or to use the MCUXpresso IDE
with CMSIS-DAP protocol.
The Link2 flash is pre-programmed
with a version of CMSIS-DAP firmware
by default.
Open Schematic
JP2
Buffer Power Selection
For On-board Target place in position
1-2 (default)
For Off-board Target place in position
2-3
1-2 Schematic
JP3
Target processor selection for the on-
board Debug Probe.
Jumper open (default) the i.MX RT685
Target SWD interface enabled.
Normal operating mode where the
Open Schematic
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Table 2. Indicators and jumpers (continued)
Circuit ref (Rev E) Description Default Reference
Target SWD is connected to either the
on-board Link2 Debug Probe or an
external Debug Probe.
Jumper shunted, the i.MX RT685
Target SWD interface is disabled. Use
this setting only when the on-board
Link2 Debug Probe is used to debug
an off-board target MCU.
JP4
When open (default), the Bridge UART
and SPI connections from the Link2
probe are driven to the i.MX RT685
target.
Install JP4 when using the SPI
interface at connector J36 and/or FC0
UART at J16. Note that this disables
the Link2 SPI and UART (VCOM/
bridge) connections.
Open Schematic
JP6
Interrupt source select for audio
devices, controlling which audio
device drives the interrupt to i.MX
RT685 Port 0 pin 0. Insert in position
1-2 for the audio codec or 2-3 for the
TFA9894 amplifiers.
2-3 (digital amplifiers) Audio Codec and Audio digital
amplifiers
JP7, JP8
I2S data select for audio devices,
controlling which audio device drives
the I2S connections to the i.MX
RT685 I2S port. Insert in position 1-2
for the audio codec or 2-3 for the
TFA9894 amplifiers. i.MX RT685
PIO0_9 used for data transmit and
PIO0_23 for data receive.
2-3 (digital amplifiers) Audio Codec and Audio digital
amplifiers
JP9, JP10
ADC reference connector
This header provides an access point
to inject positive and negative voltage
references for the i.MX RT685 ADC.
An external positive reference may be
connected to JP10 pin 2.
An external negative reference may be
connected to JP9 pin 1.
Open MIMXRT685-EVK ADC
references and inputs
JP11
Selection jumper for digital amplifier
+5V supply. Install in position 1-2 to
draw digital amplifier supply from J6
(Rev E) power connector, or in
1-2 Schematic
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Table 2. Indicators and jumpers (continued)
Circuit ref (Rev E) Description Default Reference
position 2-3 when external power
supply (J24) is used.
JP12
Voltage/supply selector for i.MX
RT685 VDDIO_1 power domain.
Selects between PMIC output
LDO2_OUT (position 2-3) or SW2_OUT
(position 1-2). The PMIC is
programmed to default to SW2_OUT at
1.8V and LDO2_OUT at 3.3 V, but can
be re-programmed on-the-fly by the
i.MX RT685.
1-2
SW2_OUT 1.8 V Schematic
JP13
Host ISP control selection. This
header/jumper can be used to select
which of the Port 1 pin 15 (ISP0) or
pin 16 (ISP1) signals is routed to the
Interrupt/ISP pin on the PMod/Host
connector. These signals from can be
used as GPIO/interrupts to/from the
i.MX RT685, and may be used to
determine its boot mode following
reset.
Header is not installed
by default, but position
1-2 is shorted to select
ISP1/P1-16.
Schematic
JP14
Reset enable/disable to Arduino.
Install jumper to route the i.MX
RT685 reset control signal to the
standard Arduino reset pin.
Open Schematic
JP15
Power supply to FXOS8700CQ
accelerometer. Connects 3.3 V from
linear regulator U25 to the
accelerometer 3.3 V supply input.
The I/O voltage for this device is
connected to the VDDIO_1 supply rail of
the i.MX RT685.
Closed Schematic
JP16 On button control to PMIC. Set as
directed by NXP. 1-2 Schematic
JP17, JP18, JP19
SWD port isolation jumpers. When
using the VCOM port and an external
debug probe, remove these jumpers
to prevent contention with the on-
board debug probe (LPC432x
device).
All closed Schematic
JP20
VDDIO_0 supply connection to PMIC /
external supply injection. This jumper
is provided for optional insertion of an
ammeter to measure supply current
Closed Measuring MIMXRT685-EVK
device supply current
Table continues on the next page...
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