HAL USART DMA buffer reset method?

[BSang]

Hi Community,

I find a method to reset a buffer of USART DMA Buffer.

because I use USART DMA basically.

my system is consist of android smartphone, bluetooth and microcontroller(STM32F407VET), PC

when I click a button that implemented in a android, some packet is send to the bluetooth RX

and Bluetooth TX that connected to micro controller USART3 RX.

than Received USART3 Data directly send to USART1 and I can see the packet in PC program.

(So... long)

I learned about HAL USART DMA is need a fixed buffer size.

so I designed the system the length of the packet is always fixed.

But! when the Bluetooth is connected, the packet is occurred by Bluetooth like

"Connected X" (X is MAC address of Bluetooth)

Due to the packet that I don't want, DMA buffer is shifted.

like under example.

ex)​

Normal State

​buffer size 5

send "12345" => receive​ "12345"

Abnormal state​

send "12345" => add packet "ab"=>receive​ "ab123"​

For this reason, I would like to ask community How to reset DMA buffer.

Of course, using a ring buffer is best way, but I'm not have a code that work normally, and other is I can't understand the code algorithms.

Ask for help...

Thank.

[BSang]

Thanks TJ,

what type is U1RxBufferPtrIN  and U1RxBufferPtrOUT?

char readableU1(void) {

  U1RxBufferPtrIN = U1RxBufSize - huart1.hdmarx->Instance->CNDTR;

  return U1RxBufferPtrIN - U1RxBufferPtrOUT;

}  

readableU1 is means that USART1 RX Channel is available?

It is not a clear buffer methods?

[T J]

uint32_t U1RxBufferPtrIN ;

uint32_t U1RxBufferPtrOUT=0;

make your buffer size 2^N like 256 or 512 or 1024 or 2048 or 4096 bytes

[T J]

Yes, use clear clearRxBuffer() to make the U1RxBufferPtrOUT equal to the DMA pointerIN , U1RxBufferPtrIN

then when you do readableU1() there return value will be Zero...