F4Discovery using UART1

[chrispadbury]

Posted on March 26, 2012 at 16:03

Hi, I not having much success with using the UART (USART1) on my F4Discovery board (STM32F407). I am pretty new to STM32 and Keil (the IDE I am using). Here's my code:

&sharpinclude ''stm32f4_discovery.h''

&sharpinclude ''stm32f4xx_usart.h'' &sharpinclude ''stm32f4xx.h'' void usartSetup(void); void USART_PutChar(uint8_t ch);

int main (void) {

    usartSetup();

    USART_PutChar(0);   //I realise this won't send a 0

    USART_PutChar(8);   //I realise this won't send an 8     USART_PutChar(255);   //I realise this won't send a 255

    while (1) {

        //loop forever     } }

void usartSetup (void) {

    USART_InitTypeDef USART_InitStructure;     //USART_StructInit(&USART_InitStructure);     USART_InitStructure.USART_BaudRate = 9600;     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(USART1, &USART_InitStructure);     USART_Cmd(USART1, ENABLE); }

void USART_PutChar(uint8_t ch) {

    USART_SendData(USART1, (uint16_t) 0x49);     while(USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);     USART_SendData(USART1, (uint16_t) 0x49); }

 I'd be very grateful if someone could help. It never sends the 0x49 out of the UART1 TX (have checked pin PA9 and PB6) and then gets endlessly stuck on the while(USART_GetFlagStatus...). I am observing using the Keil debugger and see it get stuck in the while. I also have a scope probe on the TX pin and never see anything.

I am including the stm32f4xx_usart.c driver into the project.

Thanks!

#rs232-uart-usart-f4discover-407 #uart #stm32f4discovery

[chrispadbury]

Posted on March 28, 2012 at 17:54

Out of interest, Is there a more elegant way to write to the upper 8 pins of portE. I am more used to eight bit micros, where it is simpler dealing with single bytes all the time.

[Tesla DeLorean]

Posted on March 28, 2012 at 19:51

GPIO_SetBits(GPIOE, (c << 8))

; You could also touch the underlying register(s).

[chrispadbury]

Posted on April 11, 2012 at 18:20

Thanks for that. A late response, but I think I would have to add a line to Reset the desired pins as well:

GPIO_ResetBits(GPIOE, ((255-c) << 8))

; So the complete section of code would be:

GPIO_SetBits(GPIOE, (c << 8))

;

GPIO_ResetBits(GPIOE, ((255-c) << 8))

;

[Tesla DeLorean]

Posted on April 11, 2012 at 18:35

I had envision just losing all the bit testing stuff, while leaving the initial clearing code, thus :

GPIO_ResetBits(GPIOE, GPIO_Pin_8 | GPIO_Pin_9 | GPIO_Pin_10 | GPIO_Pin_11 | GPIO_Pin_12 | GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15); GPIO_SetBits(GPIOE, (c << 8)); Doing a read-mask-write directly on the register would of course be a more optimal choice. There is probably also a clever trick with the 32-bit BSRR register. Perhaps : GPIOE->BSRR = ((u32)(0xFF ^ c) << 24) | (u32)(c << 8);

[jlchoobs]

Posted on April 20, 2012 at 11:04

Clive, I tried your Uart1 Example code as a new project, and it works fine.

But, when I dropped the Uart1 Code into the F4Disc Demo/Usb Project, it returned characters at the wrong speed on PB6.  Would the PbButtonInit() or anything else cause this problem - maybe Clock/PortClockSpeed ?  Nothing else is using the PB6/PB7 Pins.

[Tesla DeLorean]

Posted on April 20, 2012 at 14:00

A lot of the F4 library code assumes that the device is clocked with an external 25 MHz crystal, the F4 discovery has an 8 MHz crystal. You need to check the library, and setting of things like HSE_VALUE.

[jlchoobs]

Posted on April 20, 2012 at 18:40

Thanks Clive, I missed that.

I adjusted the PLL in the System_stm32f4xx.c File PLL_M=8 intead of 25, but did not know thast there were any other Registers.

[jihed_azaza]

Posted on May 01, 2012 at 12:50

good morning ,

how we can use the usart in order to reveive data. i want a programme thnx

[Tesla DeLorean]

Posted on May 01, 2012 at 13:31

I'd try digging through the STM32 examples.

Once you have the port configured, the reading side looks like this :

while(USART_GetFlagStatus(USART1, USART_FLAG_RXNE) == RESET); // Wait for Character
ch = USART_ReceiveData(USART1);

Personally, I'd be using interrupts and a ring buffer, but that's more involved than the simple example.

[jihed_azaza]

Posted on May 01, 2012 at 14:57

this is exactly what i want a code wich can receive a data using the mecanisme of interrupt.this a code but it don't work

/

/* ------------------------Includes ---------

-------------*/

#include ''stm32f10x.h'' #include ''stm32f10x_gpio.h'' #include ''stm32f10x_rcc.h'' #include ''stm32f10x_dma.h'' #include ''stm32f10x_usart.h'' /* Définition de la structure*/ char st[]; int i; /**************************************************************************************/ void RCC_Configuration(void) { /* --------------------------- System Clocks Configuration -----------------*/ /* Enable DMA clock */ RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE); /* Enable GPIO bank clock */ RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE); /* Enable USART1 clock */ RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE); } void GPIO_Configuration(void) { GPIO_InitTypeDef GPIO_InitStructure; /* Configure USART Rx as input floating */ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10; // PA.10 USART1.RX GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; GPIO_Init(GPIOA, &GPIO_InitStructure); } void USART1_Configuration(void) { USART_InitTypeDef USART_InitStructure; /* USARTx configuration ------------------------------------------------------*/ /* USARTx configured as follow: - BaudRate = 1200 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 = 1200; 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_Init(USART1, &USART_InitStructure); USART_Cmd(USART1, ENABLE); } void DMA_Configuration(void) { // USART1 Channel 5 DMA_DeInit(DMA1_Channel5); DMA_Cmd(DMA1_Channel5, DISABLE); } void DMA_USART_String(char *st) { DMA_InitTypeDef DMA_InitStructure; /* Disable the DMA Controller/Channel */ DMA_DeInit(DMA1_Channel5); /* USART1_Tx_DMA_Channel (triggered by USART1 Tx event) Config */ DMA_InitStructure.DMA_PeripheralBaseAddr = (u8)&USART1->DR; DMA_InitStructure.DMA_MemoryBaseAddr = (u8)st; DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST; DMA_InitStructure.DMA_BufferSize = strlen(st); DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Enable; 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_Normal; DMA_InitStructure.DMA_Priority = DMA_Priority_High; DMA_InitStructure.DMA_M2M = DMA_M2M_Disable; DMA_Init(DMA1_Channel5, &DMA_InitStructure); /* Enable the DMA Controller/Channel */ DMA_Cmd(DMA1_Channel5, ENABLE); /* Enable USART1 DMA TX request */ //USART_DMACmd(USART1, USART_DMAReq_Rx, ENABLE); /* Wait of DMA completion */ while(DMA_GetFlagStatus(DMA1_FLAG_TC4) == RESET); /* Loop until the end of transmit */ while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); } int main(void) { RCC_Configuration(); GPIO_Configuration(); USART1_Configuration(); DMA_Configuration(); while(1 ){ if(USART_GetFlagStatus(USART1,USART_IT_RXNE)==SET) { for(i=0; i<20; i++){ st[i]= USART_ReceiveData(USART1); printf('' %c'',st[i]&0xFF); /* print the input char */ } } // DR[i]=GPIO_ReadInputDataBit(GPIOA,GPIO_Pin_10); // DMA_USART_String(&DR[i]); } }; /******************** Function Name : Delay**************************/ void Delay(vu32 nCount) { for(; nCount != 0; nCount--);}