FRDM-IMX91 Board User Manual

2.11 Tri-radio module interface

The FRDM-IMX91 board features a Tri-radio (Wi-Fi 6, Bluetooth Low Energy 5.4, and 802.15.4) module based on the NXP IW612 that interfaces with the SD2, UART5, SAI1, and SPI3 controller of the target processor.

The two antenna pins (RF_ANT0 and RF_ANT1) of the module connects to U.FL connectors P9 and P10 (DNP by default). The module is supplied with VPCIe_3V3, VEXT_1V8, and VDD_1V8.

The MAYA-W476-00B module and M.2 connector share several interface lines on the FRDM-IMX91 board. Zero-ohm resistors enable signal selection between these components.

2.12 CAN interface

The i.MX 91 processor supports a controller area network (CAN) module that is a communication controller implementing the CAN protocol according to the CAN with flexible data rate (CAN FD) protocol and the CAN 2.0B protocol specification. The processor supports two CAN FD controllers.

On the FRDM-IMX91 board, one of the controllers is connected to the high-speed CAN transceiver TJA1051T/3. The high-speed CAN transceiver drives CAN signals between the target processor and a 10-pin 2x5 2.54 mm header (P12) to its physical two-wire CAN bus.

The CAN_TXD and CAN_RXD signals are multiplexed on GPIO_IO25 and GPIO_IO27, respectively. On the board, a 2-bit DIP switch (SW3) is used to control the CAN signals. For SW3 detail, see Section 1.7. The CAN_STBY signal from the IO expander PCAL6524HEAZ (U725, P2_7, I2C address: 22) enables / disables CAN standby mode.

The CAN interface circuit includes the split termination RC filter (62Ω + 56pF) for noise rejection and signal integrity. The switch SW4 is provided for enabling/disabling the RC filter. For SW4 detail, see Section 1.7.

The HS-CAN transceiver and header are described in Table 18.

2.13 USB interface

The i.MX 91 applications processor features two USB 2.0 controllers, with two integrated USB PHYs. On the FRDM-IMX91 board, one is used for the USB2.0 Type-C Port (P2) and the other is used for USB2.0 Type-A Port (P17).

Table 19 describes the USB ports available on the board.

2.14 Ethernet

The i.MX 91 processor supports two Gigabit Ethernet controllers (capable of simultaneous operation) with support for Energy-Efficient Ethernet (EEE), Ethernet AVB, and IEEE 1588.

The Ethernet subsystem of the board is provided by the Motorcomm YT8521SH-CA Ethernet transceivers (U713, U716) which support RGMII and connect to RJ45 connectors (P3, P4). The Ethernet transceivers (or PHYs) receive standard RGMII Ethernet signals from i.MX 91. The RJ45 connectors integrate Magnetic transformer inside, so they can be directly connected to Ethernet transceivers (or PHYs).

Each Ethernet port has a unique MAC address, which is fused into i.MX 91. The Ethernet connectors are labeled clearly on the board.

2.15 EXPI connector

One 2x20-pin EXPI connector (P11) is provided on the FRDM-IMX91 board to support I2S, UART, I2C, and GPIO connections. The header can be used to access various pins or to plug in accessory cards, such as the LCD display TM050RDH03-41, 8MIC-RPI-MX8 card, and MX93AUD-HAT.

The connector is shown in Figure 3.

2.16 Debug interface

The FRDM-IMX91 board features two independent debug interfaces.

• Serial wire debug (SWD) header (Section 2.16.1)
• USB-to-dual UART debug port (Section 2.16.2)

2.17 Board errata

No board errata.

3.1 5-inch Tianma LCD

TM050RDH03-41 is a 5" TFT LCD display with 800x480 resolution. This industrial-grade display uses an RGB interface without a touch panel. This display module connects to the FRDM-IMX91 through the EXPI 2x20-pin connector (P11).

$setenv fdtfile imx91-11x11-frdm-tianma-wvga-panel.dtb
$saveenv
$boot

$setenv fdtfile imx91-11x11-frdm-aud-hat.dtb
$saveenv
$boot

$setenv fdtfile imx91-11x11-frdm-8mic.dtb
$saveenv
$boot

4 PCB information

The FRDM-IMX91 is made with standard 10-layer technology. The material is FR-4, and the PCB stack-up information is described in Table 22.

Finished: 1.6 mm
Designed: 71.304 mil
Material: FR-4

5 European Union regulatory compliance

Table 23 is provided as per Article 10.8 of the Radio Equipment Directive 2014/53/EU.

(a) Frequency bands in which the equipment operates.

(b) The maximum RF power transmitted.

EUROPEAN DECLARATION OF CONFORMITY (Simplified DoC per Article 10.9 of the Radio Equipment Directive 2014/53/EU)

This apparatus, namely FRDM-IMX91 Freedom Development Platform, conforms to the Radio Equipment Directive 2014/53/EU. The full EU Declaration of Conformity for this apparatus can be found at the NXP website: FRDM-IMX91.

6 Acronyms

Table 24 lists and explains the acronyms and abbreviations used in this document.

7 Related documentation

Table 25 lists and explains the additional documents and resources that you can refer to for more information on the FRDM-IMX91 board. Some of the documents listed below may be available only under a nondisclosure agreement (NDA). To request access to these documents, contact your local field applications engineer (FAE) or sales representative.

8 Note about the source code in the document

The example code shown in this document has the following copyright and BSD-3-Clause license:

Copyright 2025 NXP Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
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3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

9 Revision history

Table 26 summarizes the revisions to this document.

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