DMA uart transfers

[John Hite]

Posted on January 27, 2017 at 20:06

I have been thrust into a situation where I realize I am in over my head. Eventually I think I will figure it out but could use a leg up with this STM32F437 device. I know little about it and especially it’s dma.

The project I have been assigned to uses DMA to communicate with the debug port UART8.

The DMAChannel is set to DMA_Channel_5, and from the table transmission for uart 8 is set for stream 0  and rx is stream6.

We are using Micrium uC/OS-III and in the interrupt vector table I see no interrupts setup for the UART but I do see an RxISR and a TxISR. From this should I assume that there is some smart linkage that lets the DMA know there are characters available at the UART.

AT startup the welcome banner is splashed. However when a character is entered to start the login process the system hangs up. Looking at the registers we see a transmit transfer error bit that will not clear.

My co-worker suspects that maybe it is due to dma transmit and receive happening at the same time but the documentation does not prohibit this as far as I know. So could this be a problem?

Thanks,

jh

[Tesla DeLorean]

Posted on January 27, 2017 at 22:40

Uses DMA1, UART8_TX Stream 0 Channel 5, UART8_RX Stream 6 Channel 5

You have to program the DMA controller to initiate any transfer. RX could be in circular mode, interrupting via the DMA HT/TC interrupts.

RX and TX can occur concurrently. You'd need to make sure buffers are not transient (local/auto), and one TX completes before starting another.

What are you looking for? Code that demonstrates DMA functionality? Using what pins?

[John Hite]

Posted on January 28, 2017 at 18:31

Thanks for the post. 

Yes, I would definitely like some good DMA/UART example code. The pins are UART8, PE0 & PE1.

Thanks,

jh

[Tesla DeLorean]

Posted on January 31, 2017 at 20:22

Quick blind UART8 TX example

// STM32 UART8 DMA TX (Tx PE.1, Rx PE.0) STM32F437 - sourcer32@gmail.com
#include 'stm32f4xx.h'
/**************************************************************************************/
void RCC_Configuration(void)
{
 /* --------------------------- System Clocks Configuration -----------------*/
 /* UART8 clock enable */
 RCC_APB1PeriphClockCmd(RCC_APB1Periph_UART8, ENABLE);
 /* GPIOE clock enable */
 RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOE, 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(GPIOE, &GPIO_InitStructure);
 /* Connect USART pins to AF */
 GPIO_PinAFConfig(GPIOE, GPIO_PinSource0, GPIO_AF_UART8); // UART8_R
X GPIO_PinAFConfig(GPIOE, GPIO_PinSource1, GPIO_AF_UART8); // UART8_T
X}
/**************************************************************************************/
void UART8_Configuration(void)
{
 USART_InitTypeDef USART_InitStructure;
 /* USARTx configuration ------------------------------------------------------*/
 /* USARTx configured as follow:
 - BaudRate = 115200 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 = 115200;
 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(UART8, &USART_InitStructure);
 USART_Cmd(UART8, ENABLE);
}
/**************************************************************************************/
char Buffer[] = 'The quick brown fox jumps over the lazy dog

';
void DMA_Configuration(void)
{
 DMA_InitTypeDef DMA_InitStructure;
 DMA_DeInit(DMA1_Stream0);
 DMA_InitStructure.DMA_Channel = DMA_Channel_5;
 DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral; // Transmit
 DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)Buffer;
 DMA_InitStructure.DMA_BufferSize = (uint16_t)sizeof(Buffer) - 1;
 DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&UART8->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_Stream0, &DMA_InitStructure);
 /* Enable the USART Tx DMA request */
 USART_DMACmd(UART8, USART_DMAReq_Tx, ENABLE);
 /* Enable DMA Stream Transfer Complete interrupt */
 DMA_ITConfig(DMA1_Stream0, DMA_IT_TC, ENABLE);
 /* Enable the DMA RX Stream */
 DMA_Cmd(DMA1_Stream0, ENABLE);
}
/**************************************************************************************/
void DMA1_Stream0_IRQHandler(void)
{
 /* Test on DMA Stream Transfer Complete interrupt */
 if (DMA_GetITStatus(DMA1_Stream0, DMA_IT_TCIF0))
 {
 /* Clear DMA Stream Transfer Complete interrupt pending bit */
 DMA_ClearITPendingBit(DMA1_Stream0, DMA_IT_TCIF0);
 }
}
/**************************************************************************************/
void NVIC_Configuration(void)
{
 NVIC_InitTypeDef NVIC_InitStructure;
 /* Configure the Priority Group to 2 bits */
 NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
 /* Enable the UART8 TX DMA Interrupt */
 NVIC_InitStructure.NVIC_IRQChannel = DMA1_Stream0_IRQn;
 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
 NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
 NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
 NVIC_Init(&NVIC_InitStructure);
}
/**************************************************************************************/
int main(void)
{
 RCC_Configuration();
 NVIC_Configuration();
 GPIO_Configuration();
 UART8_Configuration();
 DMA_Configuration();
 while(1); // Don't want to exit
}
/**************************************************************************************/
#ifdef USE_FULL_ASSERT
/**
 * @brief Reports the name of the source file and the source line number
 * where the assert_param error has occurred.
 * @param file: pointer to the source file name
 * @param line: assert_param error line source number
 * @retval None
 */
void assert_failed(uint8_t* file, uint32_t line)
{
 /* User can add his own implementation to report the file name and line number,
 ex: printf('Wrong parameters value: file %s on line %d

', file, line) */
 /* Infinite loop */
 while (1)
 {
 }
}
#endif
/**************************************************************************************/
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[Tesla DeLorean]

Posted on January 31, 2017 at 20:32 The original post was too long to process during our migration. Please click on the provided URL to read the original post. https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006I6rQ&d=%2Fa%2F0X0000000bwr%2FS3ftGoBIoihxcqqeUKivjiX2L7uQUFgPGtvA4ZA7zD8&asPdf=false

[yoann LBY]

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[yoann LBY]

Posted on October 09, 2017 at 10:04 The original post was too long to process during our migration. Please click on the provided URL to read the original post. https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006I6tg&d=%2Fa%2F0X0000000bxa%2FGMOx4xc7fwiOSw_WqPTjrgSGtYTkI2CFGhNFoL1UmRw&asPdf=false