topic Re: LPC845: uart_transfer_dma example : how to read buffer before callback? in LPC Microcontrollers

LPC845: uart_transfer_dma example : how to read buffer before callback?

v_canoz — Fri, 10 Jul 2020 16:39:11 GMT

Hi,

I'm working on the uart_transfer_dma example for the LPC845 with ping pong buffers which are each 8 bytes sized. This works well when there is a continuous data stream.

I wonder what is the proper way to handle the case when less than 8 bytes are received and we want to process them anyway. This happens when the communication rate is very low.

Let's say I have a software timer that expires each 10ms, and I want to check if a few bytes were received on the UART. How can I check if they are some available without risk of loosing any byte?

Thanks,

Victor

Re: LPC845: uart_transfer_dma example : how to read buffer before callback?

Alice_Yang — Mon, 13 Jul 2020 08:50:35 GMT

Hello Victor,

You can just transfer 4 bytes to have a try, check whether can received.

Re: LPC845: uart_transfer_dma example : how to read buffer before callback?

v_canoz — Fri, 07 Aug 2020 13:47:33 GMT

Hello Alice,

The question is, can I flush the DMA transfer before receiving the 8 bytes?

Re: LPC845: uart_transfer_dma example : how to read buffer before callback?

Alice_Yang — Tue, 18 Aug 2020 09:16:12 GMT

Update DMA descriptor.