STM32F7 USB Device HS DMA enabled

[Momchil Stanchev]

Posted on June 12, 2017 at 17:14

I'm working on the audio example and I've made it work with Audio Class 2.0. Device enumerates and ISO packets are received.

However when I decided to enable DMA for better performance the TX line is not working. Device receives Setup packets, but cannot transmit.

In the generated from CubeMX code I saw the following:

// Be aware that enabling DMA mode will result in data being sent only by multiple of 4 packet sizes. This is due to the fact

// that USB DMA does not allow sending data from non word-aligned addresses.

Does somebody knows how 'large' is one packet or where that is defined?

Anyone bumped into that problem?

Using: 

 - System Workbench for STM32

 - STM32Cube_FW_F7_V1.7.0

#stm32-usb-dma #stm32-usb #stm32 #stm32f7

[EvgenS Po]

Hello, Momchil Stanchev!

I am working on Audio Class 2.0 device but could not get it working yet. Could you please share your source code regarding USB Audio Class 2.0?

[MGuen.1]

Hi, I will try it in the next few days, too.

It says "... data being sent only by multiple of 4 packet sizes." So what is your packet size?