UART4 on STM32F417

[martinmartin9128]

Posted on March 01, 2013 at 16:25

Hi Guys,

After reading the whole of Google and finding this thread (https://my.st.com/public/STe2ecommunities/mcu/Lists/STM32Discovery/Flat.aspx?RootFolder=%2Fpublic%2FSTe2ecommunities%2Fmcu%2FLists%2FSTM32Discovery%2F[STM32F4-Discovery]%20UART4%20Problem&FolderCTID=0x01200200770978C69A1141439FE559EB459D75800084C20D8867EAD444A5987D47BE638E0F&currentviews=4749) I'm with my hands in my hair :) I can't get the UART4 to be working.... My Source code: void Usart_Printf(void) {   usart_init();     /* Output a message on Hyperterminal using printf function */   printf(''\n\rUSART Printf Example: retarget the C library printf function to the USART\n\r''); } void usart_init(void) {   /* 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   */       GPIO_InitTypeDef GPIO_InitStructure;       USART_InitTypeDef USART_InitStructure;       /* Enable GPIO clock */       RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);       /* Enable UART clock */       RCC_APB1PeriphClockCmd(RCC_APB1Periph_UART4, ENABLE);       /* Connect PXx to USARTx_Tx*/       GPIO_PinAFConfig(GPIOC, GPIO_PinSource10, GPIO_AF_UART4);       /* Connect PXx to USARTx_Rx*/       GPIO_PinAFConfig(GPIOC, GPIO_PinSource11, GPIO_AF_UART4);       /* Configure USART Tx as alternate function  */       GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;       GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;       GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;       GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;       GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;       GPIO_Init(GPIOC, &GPIO_InitStructure);       /* Configure USART Rx as alternate function  */       GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;       GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;       GPIO_Init(GPIOC, &GPIO_InitStructure);       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 configuration */       USART_Init(UART4, &USART_InitStructure);       /* Enable USART */       USART_Cmd(UART4, ENABLE); } I think all the ports are OK (in the datasheet, 2 AF ports are mentioned for the UART4, (PA0,PA1 and PC10 and PC11), which I also don't get... Can anyone help me? Thanks guys (I guess Clive will answer this one? ;) )

[Tesla DeLorean]

Posted on March 01, 2013 at 18:28

In what manner doesn't it work? Have you looked at the signals, confirmed timing and level expectations?

The code doesn't look problematic, so I think we need to widen our view of how it's attached to the outside world. The 3V CMOS outputs from the STM32 are not compatible with RS232 levels, so a converter of some manner is required. The AF pin muxing matrix allows you to escape UART4 out of a couple of pins. You couple route them both to come out the A ports, or the C ports, or one on A, the other on C. It really depends on your pin utilization for this and other peripherals, and what works best for routing the PCB design.

[Tesla DeLorean]

Posted on March 01, 2013 at 18:39

// STM32 UART4 (Tx PC.10, Rx PC.11) STM32F4 Discovery - sourcer32@gmail.com
// PC11 technically conflicts with SCLK on CS43L22
#include ''stm32f4_discovery.h''
/**************************************************************************************/
void RCC_Configuration(void)
{
/* --------------------------- System Clocks Configuration -----------------*/
/* UART4 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_UART4, ENABLE);
/* GPIOC clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
}
/**************************************************************************************/
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/*-------------------------- GPIO Configuration ----------------------------*/
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10 | GPIO_Pin_11;
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(GPIOC, &GPIO_InitStructure);
/* Connect USART pins to AF */
GPIO_PinAFConfig(GPIOC, GPIO_PinSource10, GPIO_AF_UART4);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource11, GPIO_AF_UART4);
}
/**************************************************************************************/
void UART4_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(UART4, &USART_InitStructure);
USART_Cmd(UART4, ENABLE);
}
/**************************************************************************************/
int main(void)
{
RCC_Configuration();
GPIO_Configuration();
UART4_Configuration();
while(1)
{
while(USART_GetFlagStatus(UART4, USART_FLAG_TXE) == RESET); // Wait for Empty
USART_SendData(UART4, 0x49); // Send 'I'
}
while(1); // Don't want to exit
}

[Tesla DeLorean]

Posted on March 01, 2013 at 18:40

Ok, what tool chain are you using? And how do you expect it to associate UART4 with stdout via printf()/putchar()/puts(), etc?

[martinmartin9128]

Posted on March 01, 2013 at 23:00

Hi Clive,

Thanks for the swift and extended replies! The answers: Toolchain used: arm-none-eabi-gcc-4_6 I connected the UART4 Rx and Tx to a FTDI232RL (CMOS to USB controller via virtual comport, chip should accept 3.3 volt IO) I havn't hooked up a scope yet, I wanted to let my code checked first. And I was under the impression that the printf() function was retargeted to the UART4, but now I'm not sure if that is the case...... I will test it with your

USART_SendData(UART4, 0x49); // Send 'I'

statement. Thanks for the help and insight :)