Usage of DMA in IMX7 on cortex m4

[Eray]

Hello,

We are using imx7 in a project. I am developing the Cortex m4 software. I want to use DMA with UART, I2S and SPI peripheral’s in the project. Is there a document or example that explains how to use DMA on the Cortex m4 side? I searched on the forum page but couldn’t find it.

Thanks in advance for your answers

[ToradexAI]

Hi, I’m the Toradex AI Assistant. The Toradex Support team will follow up with you shortly!

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Hello,

Thank you for reaching out with your question. Implementing DMA with peripherals such as UART, I2S, and SPI on the Cortex-M4 of the iMX7 is indeed possible and can enhance the efficiency of your project.

To get started, here are some general steps you can follow:

1. Understand the Peripheral and DMA Controller: Begin by reviewing the iMX7 reference manual. This document is crucial as it provides detailed information about the DMA controller and the specific peripherals you plan to use.

2. Configure the Resource Domain Controller (RDC): Ensure that the DMA controller and the peripherals are correctly assigned to the Cortex-M4 domain. This involves setting up the RDC to allow the Cortex-M4 to access these resources.

3. Set Up Your Development Environment: Depending on whether you are using FreeRTOS or a bare-metal approach, set up your development environment accordingly. Toradex provides FreeRTOS examples that can be adapted for DMA usage.

4. Initialize DMA and Peripheral Drivers: Develop or modify existing drivers to initialize the DMA controller and configure it for your peripherals. This includes setting up DMA channels, transfer sizes, and handling interrupts.

5. Develop and Test Your Application: Implement your application logic, ensuring that DMA transfers are correctly initiated and completed. Rigorous testing is essential to ensure data integrity and performance.

While specific examples or documentation might not be readily available, the iMX7 reference manual and other technical resources from NXP can provide valuable guidance on DMA configuration and usage.

If you have any more questions or need further assistance, feel free to ask!

Best regards,
Toradex AI Assistant

Please, also check if these links can help you solve your problem:

SPI DMA on Colibri iMX7

Hi Andy, I Looked at Spi_Demo. There were 20 bytes for transfer, ok. The function itself is a synchron function, used within a task will be ok. But, did the hardware generate 20 interrupts which were handled by the ReadWrite function, which ends up in a high processor burden, or is DMA used for this job to free the processor? As the SPI interface is a very fast interface, generating an interrupt on each transferred byte isn’t that good idea (for my opinion). My application uses SPI (master on…

Enable UART4 on the verdin

Hi, My goal is to enable the UART4 interface on the Verdin. Both the online UART article and the manual list that this uart is used a the debug port of the Cortex-M4, unless you properly modify the device tree. My question is about properly modifying the device tree. The device tree in the toradex git folder for the verdin has the following UART4 entry: serial@30a60000 { compatible = "fsl,imx8mm-uart\0fsl,imx6q-uart"; reg = <0x30a60000 0x10000>; interrupts = <0x00 0x1d 0x04>; c…

https://community.nxp.com/t5/i-MX-Processors/DMA-Support-in-FreeRTOS-package-for-imx-7s/td-p/613690.

[yago.tx]

Hi @Eray,

There is no driver for the DMA on the (iMX7’s) Cortex M, and so there are no examples on how to use it. Also, to use the DMA on the Cortex M you’d have to disable it on the Cortex A, as it is shared between the two.

In this thread you may find more information about the DMA. Quoting erickrieg:

[…]. The SDMA essentially has its own microprocessor that can be programmed in assembly language. I could not find a compiler for it - but read of someone writing their own. The manual for the sdma is over 200 pages long - I could not find any white paper on how to really use it. I concluded it is just too complicated and no simple examples of how to use […]

Best Regards,
Yago