With the command length unknown, is there a documented way to use DMA?

[Vivek Patel]

I have unknown length of data to be received on UART, and It is continuous bulk of data so which is the better way to use UART, I have configured it with DMA but It is accepting defined bytes only.

Could you provide best solution which is good for this task?

Regards,

Vivek Patel

[KnarfB]

Check http://stm32f4-discovery.net/2017/07/stm32-tutorial-efficiently-receive-uart-data-using-dma/

[gregstm]

if it was me, I would use the simple approach of using a receive interrupt to fill a circular buffer. When all is working fine, then try using a circular DMA buffer only if extra efficiency is required. Never tried it, but I would try using DMA_CNDTR to calculate an "in_ptr" to compare with a user updated "out_ptr" to check/poll if data is available. I would make the buffer very large to avoid any chance of the buffer data being overwritten/overrun