Posted on September 14, 2017 at 11:35Hello,
I try to use Usart Tx with DMA on a STM32L052K6, in order to send a string
without needing to send each character independently.
I don't use ISR. The Usart TX works well without DMA using HAL functions.
The problem : when I call my function UsartTxData, there is only 2 bytes that are transferred, whereas my string is 13 characters. I've checked with debugger that CNDTR is correctly loaded to the value 13.
As soon as TCIF = 1, there is only 2 bytes transferred instead of 13, I've check Tx signal with oscilloscope.
I can not find out the problem, can you please help me ?
Thanks !
Thomas
Main :
char msg[20] = 'page keybd ';
#define BUFFER_SIZE 50
char TxBuffer[BUFFER_SIZE];
while(1)
{
UsartTxData(msg);
for(i=0;i<1000000;i++) RestartWdt(); // Delay
}
void UsartInit(void)
{
GPIO_InitTypeDef GPIO_InitStruct;
// Peripheral clock enable
__USART1_CLK_ENABLE();
// USART1 GPIO Configuration
// PB6 ------> USART1_TX
// PB7 ------> USART1_RX
GPIO_InitStruct.Pin = GPIO_PIN_6|GPIO_PIN_7;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_PULLUP;
GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF0_USART1;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
// DMA controller clock enable
RCC->AHBENR |= RCC_AHBENR_DMA1EN;
// Remap DMA channel2 on USART TX
DMA1_CSELR->CSELR |= 0x011 << DMA_CSELR_C2S_Pos;
// Configure the peripheral data register address
DMA1_Channel2->CPAR = (uint32_t) (&(USART1->TDR));
// Configure the memory address
DMA1_Channel2->CMAR = (uint32_t)(TxBuffer);
// Memory to memory transfer
DMA1_Channel2->CCR |= DMA_CCR_MEM2MEM;
// Memory increment mode enabled
DMA1_Channel2->CCR |= DMA_CCR_MINC;
// Data transfer direction, Read from memory
DMA1_Channel2->CCR |= DMA_CCR_DIR;
huart1.Instance = USART1;
huart1.Init.BaudRate = 9600;
huart1.Init.WordLength = UART_WORDLENGTH_8B;
huart1.Init.StopBits = UART_STOPBITS_1;
huart1.Init.Parity = UART_PARITY_NONE;
huart1.Init.Mode = UART_MODE_TX_RX;
huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart1.Init.OverSampling = UART_OVERSAMPLING_16;
huart1.Init.OneBitSampling = UART_ONEBIT_SAMPLING_DISABLED;
huart1.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
HAL_UART_Init(&huart1);
// DMA USART TX Enable
USART1->CR3 |= USART_CR3_DMAT;
}
void UsartTxData(char *data)
{
// Check if Tx DMA is busy
if(UsartTxBusy() == 1) return;
// Clear status / interrupt flags
DMA1->IFCR |= DMA_IFCR_CGIF2 | DMA_IFCR_CTCIF2 | DMA_IFCR_CHTIF2 | DMA_IFCR_CTEIF2;
// Set transfer data size
DMA1_Channel2->CNDTR = strlen(data);
// Copy data to buffer
strcpy(TxBuffer, data);
// Set busy flag (used in UsartTxBusy())
TxBusyFlag = 1;
// Channel Enable - start transfer
DMA1_Channel2->CCR |= DMA_CCR_EN;
}
uint8_t UsartTxBusy(void)
{
if((DMA1->ISR & DMA_ISR_TCIF2) != 0)
{
TxBusyFlag = 0;
DMA1_Channel2->CCR &= ~DMA_CCR_EN;
// Clear status / interrupt flags
DMA1->IFCR |= DMA_IFCR_CGIF2 | DMA_IFCR_CTCIF2 | DMA_IFCR_CHTIF2 | DMA_IFCR_CTEIF2;
}
return(TxBusyFlag);
}
