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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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
Table continues on the next page...
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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
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Table 2. Indicators and jumpers (continued)
Circuit ref (Rev E) Description Default Reference
to the i.MX RT685 VDDIO_0 supply
pins.
JP22 Selects the value of LDO_ENABLE.
High (1-2) or Low (2-3). Open Schematic
JP23
This jumper is provided for optional
insertion of an ammeter to measure
supply current to the i.MX RT685
VDDIO_1 supply pins.
Closed
Measuring MIMXRT685-EVK
device supply current and
Schematic
JP24
This jumper is provided for optional
insertion of an ammeter to measure
supply current to the i.MX RT685
VDDA_BIAS supply pins.
Closed Measuring MIMXRT685-EVK
device supply current and
Schematic
JP25
This jumper is provided for optional
insertion of an ammeter to measure
supply current to the i.MX RT685
VDDA_ADC1V8 supply pins.
Closed Measuring MIMXRT685-EVK
device supply current and
Schematic
JP26 This jumper is provided for optional
insertion of an ammeter to measure
supply current to the i.MX RT685
VDDA_AO supply pins.
Closed Measuring MIMXRT685-EVK
device supply current and
Schematic
JP27
This jumper is provided for optional
insertion of an ammeter to measure
supply current to the i.MX RT685
VDDIO_2 supply pins.
Closed Measuring MIMXRT685-EVK
device supply current and
Schematic
JP28
This jumper is provided for optional
insertion of an ammeter to measure
supply current to the i.MX RT685
RT685 VDD1V8 supply pins.
Closed
Measuring MIMXRT685-EVK
device supply current and
Schematic
JP29
This jumper is provided for optional
insertion of an ammeter to measure
supply current to the i.MX RT685
Core.
Closed
Measuring MIMXRT685-EVK
device supply current and
Schematic
JP30 This jumpers routes P1_5 to the
accelerometer interrupt pin. Closed Schematic
J1 Additional / spare signal expansion
header. N/A Additional expansion header
J16
UART header for i.MX RT685
Flexcom 0 UART. Note that JP4 must
be installed when using this UART to
avoid conflicts with the on-board
debug probe.
N/A USART header
J18 Header for access to I3C port. Note
that this port is also shared with the N/A I3C header
Table continues on the next page...
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Table 2. Indicators and jumpers (continued)
Circuit ref (Rev E) Description Default Reference
audio devices on the board (codec
and amplifiers).
J25, J26 Ground headers, provided for
convenient connection to ground. N/A Schematic
J35
Host reset control header. Provides a
connection point for an external host
to drive the reset of the i.MX RT685
(and other devices sharing this reset).
Open Schematic
J38
Footprint-only for Trace Mictor 38
Adapter gives you the ability to
perform trace.
N/A Schematic
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Chapter 3
Getting started
This section describes how to first power up the board and then how to start a first debug session using the MCUXpresso SDK.
The board is pre-programmed with a simple program indicating that the target MCU is running. Connect a micro USB cable from
connector J5 (LINK USB) to a host computer or power supply to power-up the board and run this program.
The following debug probes can be used with the board:
• On-board debug probe (LPC4322 Link2), Cortex® M33 only.
• SEGGER J-link probes (version 9 and older)
Other debug probes may also be supported by IAR and Keil tools and by other IDEs/debug tools. Refer to the websites of these
companies for further information.
3.1 Starting a debug session using the on-board (Link2) Debug Probe
By default, the i.MX RT685 EVK is configured to use the on-board Debug Probe (Link2) to debug the on-board target (i.MX
RT685), using the CMSIS-DAP debug protocol pre-programmed into the Link2 Flash memory. The MCUXpresso IDE or other
development tools that support the CMSIS-DAP protocol can be used in the default configuration (once support is released for
those tools). Check with your toolchain vendor for availability of specific device support packs for the i.MX RT685 series devices.
When using the MCUXpresso IDE, the on-board Link2 can also be booted in the DFU mode (see jumper settings). If this is done,
MCUXpresso IDE will download CMSIS-DAP to the probe as needed. Using the DFU boot mode will ensure that the most up-to-
date/compatible firmware image is used with the MCUXpresso IDE.
If the Debug Probe is set up to boot in DFU mode, the USB bridge functions (virtual COM port) and Debug Probe
features will not be available if the board is not first initialized by the MCUXpresso IDE.
NOTE
3.1.1 Installation steps to use with MCUXpresso IDE
1. Download and install the MCUXpresso IDE.
2. Configure and download an SDK package (with the MCUXpresso IDE tool chain option selected) from the MCUXpresso
SDK Builder utility (http://mcuxpresso.nxp.com).
Install JP1 to force the Link2 Debug Probe to boot in DFU mode (see Note in Starting a debug session using the on-board
(Link2) Debug Probe).
3. Ensure that:
• The jumper is fitted in position, local target powered.
• The jumper is not installed, target SWD enabled.
These are the default positions set during board manufacture.
4. Connect the board to the USB port of your host computer, connecting a micro USB cable to connector J5.
5. Allow about 10 seconds for the i.MX RT685 EVK device to enumerate for the first time. The device will appear as LPC-
Link2 UCom Port.
If the first attempt to debug a project fails in the IDE, cancel the debug session and repower the board. On some machines the
drivers take longer to enumerate for the first time, so these steps should correct this issue.
When the board is used for the first time, it is recommended to force the i.MX RT685 target into a known state by performing an
ISP boot before attempting to run your first example code. This can be achieved by pressing and holding down the ISP button
while pressing and releasing the reset button.
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3.1.2 Installation steps to use Keil and IAR tools
1. Download and install LPCScrypt or the Windows drivers for LPCXpresso boards (http://www.nxp.com/lpcutilities). This will
install required drivers for the board.
The Link2 (LPC4322 device) is pre-programmed with CMSIS-DAP firmware during manufacture, so you do not
need to program it.
NOTE
2. Ensure JP1 is open to force the Link2 Debug Probe to boot from internal flash.
3. Ensure jumper JP2 is fitted in position 1-2, and JP3 is not installed. These are the default positions set during board
manufacture.
4. Connect the i.MX RT685 board to the USB port of your host computer, connecting a micro USB cable to connector J5
(Link USB). Allow about 30 seconds for the Link2 devices to enumerate for the first time. It is not necessary to check the
Hardware Manager. If this is done, there will be:
• five devices (if using CMSIS-DAP protocol).
• four under Human Interface Devices (CMSIS-DAP, LPC-SIO, two HID Compliant Devices, and a USB Input
Device).
• one under Ports (LPC-LinkII UCom.).
Your board is now ready to use with your 3rd-party tool. Follow the instructions for those tools for using a CMSIS-DAP probe.
MCUXpresso IDE can also be used with the board after setting up the board this way.
3.1.3 Starting a debug session using an external Debug Probe
Code running on the i.MX RT685 target can be debugged using an external Debug Probe that conforms to the standard Arm®
Cortex-M debug connectors (either 10 or 20 pin). To use an external Debug Probe connect the probe to one of the SWD
connectors (J2 or J19) and connect power via the micro USB connector J6.
When using a Revision E board, the Debug link connector (J5) can still be used to power the board, and the VCOM function of
the LPC432x can also be used, but JP17, JP18 and JP19 must be removed to prevent contention between the external and on-
board debug probes on the SWD port of the i.MX RT685.
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Chapter 4
On-board (Link2) debug probe
This section describes the features provided by the on-board Link2 Debug Probe, including how to use this to debug an external
target.
The Link2 Debug Probe is implemented using an LPC43xx MCU, which provides a high-speed USB port interface to the host
computer that runs the development tools. This device is not intended for developer use and should only be used with approved
firmware images from NXP. The Link2 on-chip flash memory is factory programmed with a firmware image that supports CMSIS-
DAP debug protocol, but also includes other USB end point functions.
• Virtual COM (VCOM) port: a serial device that can be used with any host computer application design for serial port
communication (e.g. Teraterm, puTTY, etc.). Set the terminal program for baud rate to 115200, no parity, 8 bit data, 1 stop
bit, no flow control.
• SWO trace end point: this virtual device is used by MCUXpresso to retrieve SWO trace data. See the MCUXpresso IDE
documentation for more information.
• I2C/SPI bridges: bridge device from I2C and SPI ports of the MCU target.
All of these devices are independent of each other and of the CMSIS-DAP debug device that is enumerated when the board is
connected to a host computer; for example, the VCOM port can be used if the board is running an application when no debugger
is running.
In order to correctly install and use the Link2 device on the i.MX RT685 EVK (required for any debugging purpose) for Windows
7 (or later) host computers, install the drivers first. These drivers will automatically be installed when MCUXpresso IDE has already
been installed. If these IDEs are not being used, it is recommended LPCScrypt be installed as this also includes the required
drivers. All these tools and utilities are available for free download at https://www.nxp.com/lpcscrypt.
The CMSIS-DAP firmware image installed at the factory (and by LPCScrypt) will uniquely identify itself to the host computer so
that more than one board can be connected to that host computer at any time. Some toolchains cannot discern between multiple
debug devices. Refer to your toolchain documentation for more information.
The MCUXpresso does support multiple LPCXpresso board targets. It is strongly recommended that LPCScrypt be used to update
the Debug Probe firmware in order to ensure the latest version is being used.
The Link2 only boots when the board is power cycled. The reset button on the board does not reset the Link2.
NOTE
When using MCUXpresso IDE, the Link2 can be automatically booted with the latest/most appropriate firmware for that IDE
version by installing JP1 DFU jumper before powering up the board. This is the recommended approach for the MCUXpresso IDE.
If JP1 is installed when powering the board then the VCOM port (and other devices mentioned above) device will not appear until
the MCUXpresso IDE boots the Debug Probe. The Debug Probe is booted once a debug session is started (that is, the IDE
attempts to download code to the target).
4.1 Programming the Link2 firmware
As mentioned earlier in this section, it is not normally necessary to program the Link2 firmware. However, this can easily be
accomplished using the supporting utility, LPCScrypt.
To program the Link2 Flash the Link2 device (LPC432x) must be in DFU mode. If the Link2 already has a valid image in the flash,
it will need to be forced into DFU mode by placing a jumper shunt on JP1, and power cycling (disconnecting then reconnecting
power). Link2 MCU programming is performed using the LPCScrypt utility (see http://www.nxp.com/lpcscrypt). Instructions for
using the tool are located at the same web page.
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4.2 VCOM port
The identifier of the VCOM port will vary between boards and hosts as each board will enumerate with a unique identifier. On
Windows, to determine the COM port, open the Windows operating system Device Manager. This can be achieved by going to
the Windows operating system Start menu and typing Device Manager in the search bar. In the Device Manager under Ports;
the LPC-LinkII UCom Port device and its name should be visible.
This VCOM port will only appear:
• if the Debug Probe has been programmed with the CMSIS-DAP firmware and the Debug Probe DFU link
(JP1) is removed at power up.
• if the Debug Probe has been configured for DFU boot (JP1) installed at power up and MCUXpresso IDE has
booted it (by starting a debug session).
NOTE
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On-board (Link2) debug probe
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Chapter 5
Board power
The MIMXRT685-EVK requires +5 V input to power the on-board voltage low dropout linear regulators, of which there are 3.
Link2 Debug probe has a 2.5 V regulator (U14) which draws power from USB connector J5 (LINK USB) only. The debug probe
is unpowered if J5 is unconnected.
There are two other regulators, both providing the option of 3.3 V, one (U25) for Arduino Interface (DCDC_3V3), Accelerometer
sensor (VDD_ACCEL) and USART (VDD_LDO_3V3) the other for SD Card supply (U23); these regulators can be powered by any of
the following (+5V) sources:
• USB Debug Link connector (J5)
• USB External +5V only connector (J6)
• USB High Speed connector (J7)
The +5 V sources above are connected via protection diodes to prevent reverse powering of any of them by another source. Note
that if J7 is configured as USB host port then that connector will not supply power to the board and another source must be
provided.
For further details on the power sequence needed by the RT600, please refer to Power Sequencing in the device data sheet.
5.1 Measuring MIMXRT685-EVK device supply current
Current supply to the RT685 Core can be measured via JP29 (VDDCORE). The voltage supplied can be measured on TP19 (SW1_OUT
output voltage from PMIC).
GPIO current supplies can be measured via JP20 (VDDIO_0), JP23 (VDDIO_1) and JP27 (VDDIO_2).
Other headers to measure power are JP24 (VDDA_BIAS), JP25 (VDDA_ADC1V8), JP26 (VDDA_AO) and JP28 (VDD1V8).
For further details refer to boards schematics.
5.2 PMIC (PCA9420)
The MIMXRT685-EVK has a Power Management Integrated Circuit. Using the PMIC adds flexibility to configure the power supply
rails according to the needs of the application. PMIC has four output voltages, SW1_OUT, SW2_OUT, LDO1_OUT, and LDO1_OUT.
Table 3. PMIC Output voltages
PMIC output voltage RT00 input voltage Output voltage ranges Default value
SW1_OUT VDDCORE 0.5 - 1.5 V 1.0 V
SW2_OUT
VDDIO_0
VDD1V8
VDDA_ADC1V8
VDDIO_1 (JP12, 1-2)
1.5 - 2.1 V/2.7 - 3.3 V 1.8 V
LDO1_OUT VDD_A0 1.7 - 1.9 V 1.8 V
LDO2_OUT
VDDIO_2
VDDIO_1 (JP12, 2-3)
1.5 - 2.1 V/2.7 - 3.3 V 3.3 V
PMIC is configured via I2C and external pins.
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Table 4. PMIC pins
PMIC IMXRT685
SCL PMIC_I2C_SCL
SDA PMIC_I2C_SDA
MODESEL0 PMIC_MODE0
MODESEL1 PMIC_MODE1
INT PMIC_IRQ_N
SYSREST RESET
ON SW4 (JP16, 1-2)
For further information, please refer to the board schematic.
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Board power
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Chapter 6
Board serial connections
This section describes connections between MIMXRT685-EVK on-board serial peripherals and connectors for use with off-board
devices.
6.1 USB high-speed port
The board incorporates micro AB connector for of USB0 (High Speed, connector J7) port of the MIMXRT685-EVK. USB0 port
can operate as a device or a host.
The resistor divider on the VBUS pin (R54 and R55) should be depopulated if user chooses to use the VBUS_VALID comparator
to monitor the VBUS supply for a host mode application.
The power must be supplied to the board via the external power-only USB connector (J6) when this USB port is
configured for host operation.
NOTE
For further details, please refer to the High Speed Device/Host Controller on the User Manual.
6.2 USART header
Header J16 is provided as a convenient way to use the USART with a serial to USB cable. Flexcom 0 ports (P0_1 and P0_2) are
used for this feature, since these ports are assigned for USART ISP mode.
These ports are shared with the Link2 debug probe (LPC4322) and PMod connector. When using this header, ensure that there
is no conflicting device connected to the PMod connector and that jumper JP21 [2-3] is set to disable the connection to the Link2.
6.3 I3C header
The MIMXRT685-EVK provides a header (J18) to easily interface with an I3C serial interface.
6.4 Flexcomm header
The MIMXRT685-EVK provides a Flexcomm interface (J47) with up to eight configurable universal serial interface modules. Each
module can be configured as: USART, I2C Bus, SPI Interface or I2S interface for digital audio.
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Figure 4. i.MX RT685 EVK Flexcomm pinout
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Board serial connections
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