UART DMA STM32F4 Discovery

[tengaimakyou]

Posted on December 03, 2013 at 21:45

Hello

I found an example of using DMA with UART on STM32F407 on this thread UART with DMA mode but i can't make it work. I use a STM32F4-Discovery and i try to see if DMA1_Stream2_IRQHandler is called using the line STM_EVAL_LEDOn(LED5) in this handler. here is my code with the 3 main files main.c , stm32f4xx_it.c and stm32f4xx_it.h : main.c

#include ''stm32f4_discovery.h''
void RCC_Configuration(void)
{
/* --------------------------- System Clocks Configuration -----------------*/
/* UART4 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_UART4, ENABLE);
/* GPIOA clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
/* DMA1 clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);
}
/**************************************************************************************/
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/*-------------------------- GPIO Configuration ----------------------------*/
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Connect USART pins to AF */
GPIO_PinAFConfig(GPIOA, GPIO_PinSource0, GPIO_AF_UART4);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource1, GPIO_AF_UART4);
}
/**************************************************************************************/
void UART4_Configuration(void)
{
USART_InitTypeDef USART_InitStructure;
/* USARTx configuration ------------------------------------------------------*/
/* USARTx configured as follow:
- BaudRate = 4800 baud
- Word Length = 8 Bits
- One Stop Bit
- No parity
- Hardware flow control disabled (RTS and CTS signals)
- Receive and transmit enabled
*/
USART_InitStructure.USART_BaudRate = 4800;
USART_InitStructure.USART_WordLength = USART_WordLength_8b;
USART_InitStructure.USART_StopBits = USART_StopBits_1;
USART_InitStructure.USART_Parity = USART_Parity_No;
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
USART_Init(UART4, &USART_InitStructure);
USART_Cmd(UART4, ENABLE);
}
/**************************************************************************************/
volatile char Buffer[] = ''first uart test with stm32f4\r\n'';
void DMA_Configuration(void)
{
DMA_InitTypeDef DMA_InitStructure;
DMA_DeInit(DMA1_Stream2);
DMA_InitStructure.DMA_Channel = DMA_Channel_4;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory; // Receive
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)Buffer;
DMA_InitStructure.DMA_BufferSize = (uint16_t)sizeof(Buffer);
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&UART4->DR;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Enable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA1_Stream2, &DMA_InitStructure);
/* Enable the USART Rx DMA request */
USART_DMACmd(UART4, USART_DMAReq_Rx, ENABLE);
/* Enable DMA Stream Half Transfer and Transfer Complete interrupt */
DMA_ITConfig(DMA1_Stream2, DMA_IT_TC | DMA_IT_HT , ENABLE);
/* Enable the DMA RX Stream */
DMA_Cmd(DMA1_Stream2, ENABLE);
}
/**************************************************************************************/
void NVIC_Configuration(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
/* Configure the Priority Group to 2 bits */
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
/* Enable the UART4 RX DMA Interrupt */
NVIC_InitStructure.NVIC_IRQChannel = DMA1_Stream2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
int main(void)
{
STM_EVAL_LEDInit(LED5);
RCC_Configuration();
NVIC_Configuration();
GPIO_Configuration();
UART4_Configuration();
DMA_Configuration();
while (1) {}
}

stm32f4xx_it.c 

#include ''stm32f4xx_it.h''
#include ''stm32f4_discovery.h''
void DMA1_Stream2_IRQHandler(void)
{
STM_EVAL_LEDOn(LED5);
/* Test on DMA Stream Transfer Complete interrupt */
if (DMA_GetITStatus(DMA1_Stream2, DMA_IT_TCIF2))
{
/* Clear DMA Stream Transfer Complete interrupt pending bit */
DMA_ClearITPendingBit(DMA1_Stream2, DMA_IT_TCIF2);
USART_SendData(UART4, 'C');
}
/* Test on DMA Stream Half Transfer interrupt */
if (DMA_GetITStatus(DMA1_Stream2, DMA_IT_HTIF2))
{
/* Clear DMA Stream Half Transfer interrupt pending bit */
DMA_ClearITPendingBit(DMA1_Stream2, DMA_IT_HTIF2);
USART_SendData(UART4, 'H');
}
}

and stm32f4xx_it.h

#ifndef __STM32F4xx_IT_H
#define __STM32F4xx_IT_H
#ifdef __cplusplus
extern ''C'' {
#endif
#include ''stm32f4xx.h''
void DMA1_Stream2_IRQHandler(void);
#ifdef __cplusplus
}
#endif
#endif

I added the necessary files stm32f4xx_usart.c , stm32f4xx_dma.c... I didn't plug anything on the board, the code compile, it seems to work but the handler is never called, do i forgot something ? Thanks for your help #uart-dma-stm32f407

[Tesla DeLorean]

Posted on December 03, 2013 at 22:53

Does the UART work in polling mode?

You'd need to receive about 12 characters before you got an interrupt.

[tengaimakyou]

Posted on December 03, 2013 at 23:36

why 12 caracters, is it because of a timing thing ?

I believed that this code was working in interrupt mode (that's what i need) not polling ( there is nothing in the while loop) because there is a configuration of NVIC_Configuration and a call to DMA_ITConfig(DMA1_Stream2, DMA_IT_TC | DMA_IT_HT , ENABLE); but from your response, i begin to believe to thing that interrupt and polling are both working at the same time.  

[Tesla DeLorean]

Posted on December 04, 2013 at 01:13

How large is the buffer? Divide that by two.

[tengaimakyou]

Posted on December 04, 2013 at 14:31

Does the UART work in polling mode?
You'd need to receive about 12 characters before you got an interrupt.

The UART doesn't seems to be working in polling mode. (do i need to enable the interrupt on the usart too or only on DMA like in the example?) I am actually interested in transmitting characters, not receiving and i use the USART2 on PA2, the clock is to the same, i guess it's mean no big changes I just change a few line to fit this modification.

#include ''stm32f4_discovery.h''
void RCC_Configuration(void)
{
/* --------------------------- System Clocks Configuration -----------------*/
/* USART2 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
/* GPIOA clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
/* DMA1 clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);
}
/**************************************************************************************/
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/*-------------------------- GPIO Configuration ----------------------------*/
// GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Connect USART pins to AF */
// GPIO_PinAFConfig(GPIOA, GPIO_PinSource0, GPIO_AF_USART2);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2);
}
/**************************************************************************************/
void USART2_Configuration(void)
{
USART_InitTypeDef USART_InitStructure;
/* USARTx configuration ------------------------------------------------------*/
/* USARTx configured as follow:
- BaudRate = 4800 baud
- Word Length = 8 Bits
- One Stop Bit
- No parity
- Hardware flow control disabled (RTS and CTS signals)
- Receive and transmit enabled
*/
USART_InitStructure.USART_BaudRate = 4800;
USART_InitStructure.USART_WordLength = USART_WordLength_8b;
USART_InitStructure.USART_StopBits = USART_StopBits_1;
USART_InitStructure.USART_Parity = USART_Parity_No;
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
USART_Init(USART2, &USART_InitStructure);
USART_Cmd(USART2, ENABLE);
}
/**************************************************************************************/
volatile char Buffer[6] = ''ABCDEF'';
void DMA_Configuration(void)
{
DMA_InitTypeDef DMA_InitStructure;
DMA_DeInit(DMA1_Stream2);
DMA_InitStructure.DMA_Channel = DMA_Channel_4;
// DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory; // Receive
DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral; // Transmit
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)Buffer;
DMA_InitStructure.DMA_BufferSize = (uint16_t)sizeof(Buffer);
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&USART2->DR;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Enable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA1_Stream2, &DMA_InitStructure);
/* Enable the USART Rx DMA request */
//USART_DMACmd(USART2, USART_DMAReq_Rx, ENABLE);
/* Enable the USART Tx DMA request */
USART_DMACmd(USART2, USART_DMAReq_Tx, ENABLE);
/* Enable DMA Stream Half Transfer and Transfer Complete interrupt */
DMA_ITConfig(DMA1_Stream2, DMA_IT_TC | DMA_IT_HT , ENABLE);
/* Enable the DMA RX Stream */
DMA_Cmd(DMA1_Stream2, ENABLE);
}
/**************************************************************************************/
void NVIC_Configuration(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
/* Configure the Priority Group to 2 bits */
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
/* Enable the USART2 RX DMA Interrupt */
NVIC_InitStructure.NVIC_IRQChannel = DMA1_Stream2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
int main(void)
{
STM_EVAL_LEDInit(LED5);
RCC_Configuration();
NVIC_Configuration();
GPIO_Configuration();
USART2_Configuration();
DMA_Configuration();
while (1) {}
}

[Tesla DeLorean]

Posted on December 04, 2013 at 17:13

USART2_TX = DMA1 Channel4 Stream6 - Review the Reference Manual to understand the correlation.

Don't enable interrupts unless you plan on servicing them. Doing an HT/TC interrupt every 3 character isn't something I'd do, you might want to consider how you want to manage the data output. A string with 6 characters takes 7 bytes (string + NUL)