HAL_UART_Transmit_DMA

[NSing.5]

i'veA question related to transmission using DMA. i'm facing a strange situation.

1. it works perfectly when i use "HAL_UART_Transmit_DMA(&huart1, TxBuf, 5);" in the main program.
2. However in my project i've crated a separate file for my application program, which i include in the main program, and when i call "HAL_UART_Transmit_DMA(&huart1, TxBuf, 5);" from my application program, only first two bytes are transferred as per my data rest all bytes are corrupted.

[Aymen ABBES]

Hello @NSing.5​ ,

Thanks for sharing this issue. 

To further analyze your problem could you please provide:

• The MCU you are using
• The CubeMx and you IDE versions
• The project you are working on or your *.ioc file if it is possible

Kind regards,

Aymen

[NSing.5]

The project file is attached with for your reference. i'm working on STM32F730

[gbm]

Show the declaration of TxBuf (where exactly is it declared?) and check its usage (timing). You cannot write a new value to TxBuf until the transfer is finished.

[NSing.5]

TxBuf is declared as local variable in the function that calls HAL_UART_Transmit_DMA(&huart1, TxBuf, 5); as follows:

void mstr_digno(uint8_t Device_address,uint16_t sub_code)
{
 uint8_t TxBuf[25];
 uint16_t crc_value=0;
 TxBuf[0] = Device_address;
 TxBuf[1] = 0x08; //operation code
 convert_I_To_Byte(sub_code);
 TxBuf[2] = IntegerToByte.high_byte;
 TxBuf[3] = IntegerToByte.low_byte;
 convert_I_To_Byte(Device_address);
 TxBuf[4] = IntegerToByte.high_byte;
 TxBuf[5] = IntegerToByte.low_byte;
 crc_value = CRC_Cal_Value(TxBuf,5);
 crc_value = crc_value&0xFFFF;
 convert_I_To_Byte(crc_value);
 TxBuf[6]=IntegerToByte.low_byte;
 TxBuf[7]=IntegerToByte.high_byte;
 //HAL_UART_Transmit_DMA(&huart1, TxBuf, 10);
 HAL_UART_Transmit(&huart1, TxBuf, 10,10);
}

i'm writing new data to it after 2 seconds.

[waclawek.jan]

Don't use local variable as buffer.

JW