NXP i.MX8MM EVK
Overview
i.MX8M Mini LPDDR4 EVK board is based on NXP i.MX8M Mini applications processor, composed of a quad Cortex®-A53 cluster and a single Cortex®-M4 core. Zephyr OS is ported to run on the Cortex®-A53 core.
Board features:
RAM: 2GB LPDDR4
Storage:
SanDisk 16GB eMMC5.1
Micron 32MB QSPI NOR
microSD Socket
Wireless:
WiFi: 2.4/5GHz IEEE 802.11b/g/n
Bluetooth: v4.1
USB:
OTG - 2x type C
Ethernet
PCI-E M.2
Connectors:
40-Pin Dual Row Header
LEDs:
1x Power status LED
1x UART LED
Debug
JTAG 20-pin connector
MicroUSB for UART debug, two COM ports for A53 and M4
More information about the board can be found at the NXP website.
Supported Features
The Zephyr imx8mm_evk board for Cortex-A53 configuration supports the following hardware features:
Interface |
Controller |
Driver/Component |
|---|---|---|
GIC-v3 |
on-chip |
interrupt controller |
ARM TIMER |
on-chip |
system clock |
UART |
on-chip |
serial port |
The Zephyr imx8mm_evk board for Cortex-M4 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/nxp/imx8mm_evk/imx8mm_evk_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.
Devices
System Clock
This board configuration uses a system clock frequency of 8 MHz.
The M4 Core is configured to run at a 400 MHz clock speed.
Serial Port
This board configuration uses a single serial communication channel with the CPU’s UART4. This is used for the M4 and A53 core targets.
Programming and Debugging (A53)
Copy the compiled zephyr.bin to the first FAT partition of the SD card and
plug the SD card into the board. Power it up and stop the u-boot execution at
prompt.
Use U-Boot to load and kick zephyr.bin:
fatload mmc 1:1 0x93c00000 zephyr.bin; dcache flush; icache flush; dcache off; icache off; go 0x93c00000
Or kick SMP zephyr.bin:
fatload mmc 1:1 0x93c00000 zephyr.bin; dcache flush; icache flush; dcache off; icache off; cpu 2 release 0x93c00000
Use this configuration to run basic Zephyr applications and kernel tests, for example, with the Basic Synchronization sample:
# From the root of the zephyr repository
west build -b imx8mm_evk/mimx8mm6/a53 samples/synchronization
west build -t run
This will build an image with the synchronization sample app, boot it and display the following ram console output:
*** Booting Zephyr OS build zephyr-v3.1.0-3575-g44dd713bd883 ***
thread_a: Hello World from cpu 0 on mimx8mm_evk_a53!
thread_b: Hello World from cpu 0 on mimx8mm_evk_a53!
thread_a: Hello World from cpu 0 on mimx8mm_evk_a53!
thread_b: Hello World from cpu 0 on mimx8mm_evk_a53!
thread_a: Hello World from cpu 0 on mimx8mm_evk_a53!
Use Jailhouse hypervisor, after root cell linux is up:
#jailhouse enable imx8mm.cell
#jailhouse cell create imx8mm-zephyr.cell
#jailhouse cell load 1 zephyr.bin -a 0x93c00000
#jailhouse cell start 1
Programming and Debugging (M4)
The MIMX8MM EVK board 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, put the M4 in reset, set the M4 Program Counter and Stack Pointer, and get the M4 out of reset. The A53 can perform these steps at bootloader level or after the Linux system has booted.
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/nxp/imx8mm_evk/imx8mm_evk_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
Load and run Zephyr on M4 from A53 using u-boot by copying the compiled
zephyr.bin to the first FAT partition of the SD card and plug the SD
card into the board. Power it up and stop the u-boot execution at prompt.
Load the M4 binary onto the desired memory and start its execution using:
fatload mmc 0:1 0x7e0000 zephyr.bin;bootaux 0x7e0000
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 imx8mm_evk/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-v2.0.0-1859-g292afe8533c0 *****
Hello World! imx8mm_evk