Verdin iMX8M Mini

Board Overview

Verdin iMX8M Mini

Name:

verdin_imx8mm

Vendor:

Toradex AG

Architecture:

arm

SoC:

mimx8mm6

Overview

The Verdin iMX8M Mini is a System on Module based on the NXP® i.MX 8M Mini family of embedded System on Chips (SoCs). The i.MX 8M Mini family consists of the i.MX 8M Mini Quad, i.MX 8M Mini QuadLite, i.MX 8M Mini Dual, i.MX 8M Mini DualLite, i.MX 8M Mini Solo, and i.MX 8M Mini SoloLite. The top-tier i.MX 8M Mini Quad features four Cortex-A53 cores as the main processor cluster. The cores provide complete 64-bit Armv8-A support while maintaining seamless backwards compatibility with 32-bit Armv7-A software. The main cores run at up to 1.8 GHz for commercial graded products and 1.6 GHz for industrial temperature range products.

In addition to the main CPU complex, the i.MX 8M Mini features a Cortex-M4F processor which peaks up to 400 MHz. This processor is independent of the main complex and features its own dedicated interfaces while still being able to access the regular interfaces. This heterogeneous multicore system allows for the running of additional real-time operating systems on the M4 cores for time- and security-critical tasks.

• Board features:

  • RAM: 1GB - 2GB (LPDDR4)

  • Storage:

    • 4GB - 17GB eMMC

    • 2KB I²C EEPROM

  • Wireless:

    • WiFi Dual-band 802.11 ac/a/b/g/n 2.4/5 GHz

    • Bluetooth 5/BLE

  • USB:

    • 1x USB2.0 Host

    • 1x USB2.0 OTG

  • Ethernet Gigabit

  • Interfaces:

    • MIPI DSI 1x4 Data Lanes

    • PCIe Gen 2

    • MIPI CSI-2

    • SPI

    • QSPI

    • UART

    • I²C

    • I²S

    • SD/SDIO/MMC

    • GPIOs

    • CAN

    • ADC

    • S/PDIF

  • Debug

    • JTAG 10-pin connector

More information about the board can be found at the Toradex website.

Supported Features

The Zephyr verdin_imx8mm/mimx8mm6/m4 board target supports the following hardware features:

Interface	Controller	Driver/Component
NVIC	on-chip	nested vector interrupt controller
SYSTICK	on-chip	systick
CLOCK	on-chip	clock_control
PINMUX	on-chip	pinmux
UART	on-chip	serial port-polling; serial port-interrupt
GPIO	on-chip	GPIO output GPIO input

The default configuration can be found in the defconfig file: boards/toradex/verdin_imx8mm/verdin_imx8mm_mimx8mm6_m4_defconfig.

It is recommended to disable peripherals used by the M4 core on the Linux host.

Other hardware features are not currently supported by the port.

Connections and IOs

UART:

Zephyr is configured to use the UART4 by default, which is connected to the FTDI USB converter on most Toradex carrier boards.

This is also the UART connected to WiFi/BT chip in modules that have the WiFi/BT chip. Therefore, if UART4 is used, WiFI/BT will not work properly.

If the WiFi/BT is needed, then another UART should be used for Zephyr (UART2 for example). You can change the UART by changing the zephyr,console and zephyr,shell-uart in the boards/toradex/verdin_imx8mm/verdin_imx8mm_mimx8mm6_m4.dts file.

Board Name	SoC Name	Usage
UART_1	UART2	General purpose UART
UART_2	UART3	General purpose UART
UART_3	UART1	Cortex-A53 debug UART
UART_4	UART4	Cortex-M4 debug UART

GPIO:

All the GPIO banks are enabled in the dts/arm/nxp/nxp_imx8m_m4.dtsi.

LED:

There is no LED in the module itself, this is dependent on the carrier board that is being used with the module. The device tree is configured to use the GPIO3_IO1, which can be connected to the LED of the Verdin Development Board or changed in the boards/toradex/verdin_imx8mm/verdin_imx8mm_mimx8mm6_m4.dts if needed.

System Clock

The M4 Core is configured to run at a 400 MHz clock speed.

Programming and Debugging

The i.MX8MM doesn’t have QSPI flash for the M4 and it needs to be started by the A53 core. The A53 core is responsible to load the M4 binary application into the RAM, putting the M4 in reset, setting the M4 Program Counter and Stack Pointer, and get the M4 out of reset. The A53 can perform these steps at the bootloader level or after the Linux system has booted via RemoteProc.

The M4 can use up to 3 different RAMs. These are the memory mapping for A53 and M4:

Region	Cortex-A53	Cortex-M4 (System Bus)	Cortex-M4 (Code Bus)	Size
OCRAM	0x00900000-0x0093FFFF	0x20200000-0x2023FFFF	0x00900000-0x0093FFFF	256KB
TCMU	0x00800000-0x0081FFFF	0x20000000-0x2001FFFF		128KB
TCML	0x007E0000-0x007FFFFF		0x1FFE0000-0x1FFFFFFF	128KB
OCRAM_S	0x00180000-0x00187FFF	0x20180000-0x20187FFF	0x00180000-0x00187FFF	32KB

For more information about memory mapping see the i.MX 8M Applications Processor Reference Manual (section 2.1.2 and 2.1.3)

At compilation time you have to choose which RAM will be used. This configuration is done in the file boards/toradex/verdin_imx8mm/verdin_imx8mm_mimx8mm6_m4.dts with “zephyr,flash” (when CONFIG_XIP=y) and “zephyr,sram” properties. The available configurations are:

"zephyr,flash"
- &tcml_code
- &ocram_code
- &ocram_s_code

"zephyr,sram"
- &tcmu_sys
- &ocram_sys
- &ocram_s_sys

Starting the Cortex-M4 via U-Boot

Load and run Zephyr on M4 from A53 using u-boot by copying the compiled zephyr.bin to the eMMC (can be the FAT or EXT4 partition). You can do it by using a USB stick or through the ethernet with the scp command, for example. Power it up and stop at the u-boot prompt.

Load the M4 binary onto the desired memory and start its execution using:

fatload mmc 0:1 ${loadaddr} zephyr.bin
cp.b ${loadaddr} 0x7e0000 <size_of_binary_in_bytes>
bootaux 0x7e0000

Or if the binary is on the ext4 partition:

ext4load mmc 0:2 ${loadaddr} /path/to/zephyr.bin
cp.b ${loadaddr} 0x7e0000 <size_of_binary_in_bytes>
bootaux 0x7e0000

If you are using TorizonCore OS, then you should use partition 1:

ext4load mmc 0:1 ${loadaddr} /path/to/zephyr.bin
cp.b ${loadaddr} 0x7e0000 <size_of_binary_in_bytes>
bootaux 0x7e0000

Starting the Cortex-M4 via RemoteProc

Copy the zepyhr.elf to /lib/firmware on the target.

Note

In order to use remoteproc you have to add imx8mm-verdin_hmp_overlay.dtbo at the end of the line in the /boot/overlays.txt, then reboot the target. If you are using TorizonCore, then this file is located at /boot/ostree/torizon-<hash>/dtb/overlays.txt.

To load and start a firmware use these commands:

verdin-imx8mm:~# echo zepyhr.elf > /sys/class/remoteproc/remoteproc0/firmware
verdin-imx8mm:~# echo start > /sys/class/remoteproc/remoteproc0/state
[   94.714498] remoteproc remoteproc0: powering up imx-rproc
[   94.720481] remoteproc remoteproc0: Booting fw image zephyr.elf, size 473172
[   94.727713] remoteproc remoteproc0: No resource table in elf
[   94.733615] remoteproc remoteproc0: remote processor imx-rproc is now up

The M4-Core is now started up and running. You can see the output from Zephyr on UART4.

Debugging

MIMX8MM EVK board can be debugged by connecting an external JLink JTAG debugger to the J902 debug connector and to the PC. Then the application can be debugged using the usual way.

Here is an example for the Hello World application.

# From the root of the zephyr repository
west build -b verdin_imx8mm/mimx8mm6/m4 samples/hello_world
west debug

Open a serial terminal, step through the application in your debugger, and you should see the following message in the terminal:

*** Booting Zephyr OS build zephyr-v3.4.0-1251-g43c549305bdb ***
Hello World! verdin_imx8mm_m4