9-bit UART receive STM32F103

I wouldn't use sizeof() in this context, use 30 if you configured the USART in 9-bit.

Mask the content if required.

Provide example data, and minimally illustrative complete example if the problem persists.

> 

I thought a 16 bit register should be used to get all 9 bits

Yes it  is indeed. USART_DR[8:0] is 9 bits

The question is, how you are going to store 9 bits. STM32 does not have bit-oriented memory like 8051. So it won't fit in one byte, and two bytes is a bit excessive.

-- pa

If you using 9bit with no parity, you just read the receive register as uint16 and use the lower 9bits.

Parity is included in the STM32 data bit length.

If you need 9 data bits with parity, your going to need to use software serial.

Not sure if there is an equivalent package for F1...

But i was able to adapt this uart emulation package for F4, so i could work with a funky device that used 9-odd-2 serial.

http://www.st.com/en/embedded-software/stsw-stm32156.html

Back in Uni, one of the networking guys gave a lecture on RS232 (way back). When asked about 2 stop bits, that is a holdover from teletypes that had a mechanical rotor to commutate the bits. 7 data bits, one parity bit, and 2 stop bits at 10 characters per second gave 110 baud. 2 stop bits wasn't used anywhere else, just for 110 baud on TTYs.

A

Thanks for all the replies,

this is what I have so far, the messages array is set to zero to eliminate any previous data, then the RX is called where I would expect the data in the RX buffer to be stored into the messages array, then buzz through a mask

void

UART_RXTX(

)

{

int

i;

int

a;

char

message[]=

'start\r\n'

;

uint16_t

messages[10];

for

(i=0;i<10;i++)

{

messages[i]=0;

}

HAL_UART_Receive(&huart2, (

uint8_t

*)messages, 10,1000);

for

(i=0;i<10;i++)

{

a=messages[i] & 0x01FF;

messages[i]=a;

}

}

in the uart.c file, it is configured as such'

else if

(uartHandle->

Instance

==USART2)

{

/* USER CODE BEGIN USART2_MspInit 0 */

/* USER CODE END USART2_MspInit 0 */

/* USART2 clock enable */

__HAL_RCC_USART2_CLK_ENABLE();

/**USART2 GPIO Configuration

PA2 ------> USART2_TX

PA3 ------> USART2_RX

*/

GPIO_InitStruct.

Pin

= GPIO_PIN_2;

GPIO_InitStruct.

Mode

= GPIO_MODE_AF_PP;

GPIO_InitStruct.

Speed

= GPIO_SPEED_FREQ_HIGH;

HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

GPIO_InitStruct.

Pin

= GPIO_PIN_3;

GPIO_InitStruct.

Mode

= GPIO_MODE_INPUT;

GPIO_InitStruct.

Pull

= GPIO_NOPULL;

HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

and

else if

(uartHandle->

Instance

==USART2)

{

/* USER CODE BEGIN USART2_MspDeInit 0 */

/* USER CODE END USART2_MspDeInit 0 */

/* Peripheral clock disable */

__HAL_RCC_USART2_CLK_DISABLE();

/**USART2 GPIO Configuration

PA2 ------> USART2_TX

PA3 ------> USART2_RX

*/

HAL_GPIO_DeInit(GPIOA, GPIO_PIN_2|GPIO_PIN_3);

So the final result is that there is nothing in the messages array, the connections were checked and all wiring is ok, however the messages array is always 0

any one have any ideas on what it could be?

So I got it to work using UART1, same configuration (different ports obviously), why does it work with UART1 and not UART2?

Thanks for all the support. What I didn't mention was that I'm running a nucleo, turns out that uart2 is configured to support the serial programming- resoldered the links and now works. Was in the nucleo instructions....