Apalis iMX8 + ixora use I2C for M41 with rpmsg

Technical Support
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1

Hi,

May I ask a quick question? Is that any connector pin I can use to connect the I2C Cortex M41 for Apalis iMX8 + ixora board. By the way, I need to use rpmsg to communication between linux and rtos.

Thanks a lot.

Tak

2

Hello @tak,

This is certainly possible. To achieve this you need to make sure the I2C interface you want to use is not being used on Linux. This can be done by disabling its node of the Linux devicetree. This can be done by using a custom devicetree or by adding a devicetree overlay.
We have many pages about this topic on the HMP Session of our developer website: Heterogeneous Multi-core Processing (HMP) Documentation Overview | Toradex Developer Center

This is also possible, but not available out of the box on our Linux images. You will need to use an additional devicetree overlay to enable the RPMsg interface.

Best Regards,
Bruno

3

Dear Bruno,

Thanks for your help. By the way, according the Apalis datasheet, the M41_I2C0_SDA and M41_I2C0_SCL are connected to X1 pin 120 and 122 respectively. However, these pins are connected with UART1_R1 and UART1_DSR in ixora board which are hard soldered to RS232 IC only. Therefore, my question is whether I can have any connector pins on ixora board so that I can connected to M41_I2C0_SDA and M41_I2C0_SCL pins? Please feel free to let me know if you have any question about my problem.

Regards,

Tak

4

Hello @tak,

The M41_I2C0_SDA and M41_I2C0_SCL are used for the tightly coupled M4_1 I2C interface. This specific interface cannot be used on any other pins on the Apalis iMX8 module.
And, as you correctly pointed out the pins are not exposed on the Ixora Carrier Board, therefore this interface cannot be used on the Ixora Carrier Board out of the box.

Other I2C interfaces can be used with the Cortex-M4 cores, as long as they are not used by the OS running on the Cortex-A cores.

Best Regards,
Bruno

5

Dear Bruno,

Sorry for bother you again. I still working on using reading I2C data for M4 core ixora carry board. May I ask is there anyway I can use the I2C1_SDA, I2C1_SCL pin on extension header X27 of ixora carry board for Apalis imx8qm M4_1 core? Or is there anyway I can connect any i2c to Apalis imx8qm M4_1 core by using ixora carrier board?

Your sincerely,

Tak

6

Hello @tak,

Using the I2C1 signal available on the Ixora extension header X27 with the Apalis iMX8 M4_1 core would be possible.
However, to do this you would need to disable it on the Linux devicetree, which would make any device connected to it only accessible via the Cortex-M4 cores.
On the Ixora Carrier Board, the following peripherals are connected to the I2C1 signal:

  • RTC
  • EEPROM
  • Touch connector for LVDS display

Best Regards,
Bruno