Hi,
I'm using the MCBSTM32E development board equiped with an STM32F103ZE microcontroller.
I configured the USART2 transmitter according the Reference Manual and it works fine.
I configured the USART2 receiver according the Reference Manual and it does not work.
3 hours of experimenting does not do the job. I did next steps: - set the CR1_UE Usart Enable bit - clr the CR1_M bit for selecting 8 data bits - set the CR2 register to 1 stopbit - set the BRR register to the desired bautrate - set the CR1_RE bit to enable the receiver - set the USART RX input pin PA3 to input float - enabled the GPIOA port pheripheral clock - enabled the USART2 peripheral clock - set the CR1_RXNEIE bit to activate receive interrupt - set the NVIC-ISER bit for USART2 (global interrupt) - write an interrupt handler
When I apply data to the RX-input nothing happens. I monitored the receive data (DR) register and status (SR) register but nothing changed. I scoped pin PA3 on the uC and it is toggling when receiving data.
When I force a receive interrupt by setting the USART2 bit in the ISPR register then the interrupt handler is executed.
I changed code to control USART1 but with same effect.
I must have forgotten some bit or made some configuration errer. It seems as if rx-data is not entering the internal shiftregister or is not sampled.
All hints and tips are welcome.
Thanks,
Henk
FIFO? How much bytes in the FIFO for an interrupt?
There is no fifo. You can use DMA mode or normal mode without DMA and without fifo. The DMA is not selected so normal mode should be active. I enabled all possible receive interrupts like Rx-data, overrun, Idle, Parity, Break but nothing happens.
did you set the clock?
/*------------------------------------------------------------------. ; Enable UART4 clocks == Diagnostics port ; '------------------------------------------------------------------*/ RCC_APB1PeriphClockCmd( RCC_APB1Periph_UART4, ENABLE );
--Cpt. Vince Foster 2nd Cannon Place Fort Marcy Park, VA
What about the respective bit in PCONP (power to peripheral) ?
Have you turned it on (power to CPU)?
>did you set the clock? Yes: - enabled the USART2 peripheral clock
>What about the respective bit in PCONP (power to peripheral) ? There is no such thing like PCONP with the STM32F103ZE microcontroller
>Have you turned it on (power to CPU)? What dou you mean?
I found out that the 'Alternate Function IO Clock' was not enabled. But after enabling it still the receiver does not work.
Did you set the RCC clock FIRST?
Yes I think so:
Below is the comment from my source code as it is execute: (I rewrote my UASRT2 code to UASRT1)
//enable the GPIO clock for port GPIOA //enable the GPIO clock for port GPIOB //set the AHB prescaler divisor to 1 (so input frequency = 8.000.000 / 1 = 8.000.000Hz) //set the ABP1 prescaler for timers divisor to 8 (so input frequency = 8.000.000 / 8 = 1.000.000Hz) //set the ABP2 prescaler for timers divisor to 8 (so input frequency = 8.000.000 / 8 = 1.000.000Hz) //reset usart1 //unreset usart1 //enable the USART1 peripheral clock //alternate function io enable //PA09 is Alternate Output Push Pull + PA10 input float // 1. Enable the USART by writing the UE bit in USART_CR1 register to 1. // 2. Program the M bit in USART_CR1 to define the word length.(bit is 0 => 8bits) // 3. Program the number of stop bits in USART_CR2. (both bits are 0 => 1 stopbit) // 5. Select the desired baud rate using the baud rate register USART_BRR (115200 baud) // 6. Set the RE bit USART_CR1. This enables the receiver which begins searching for a // start bit. //enable receive-data interrupt //enable USART1 global interrupt
1. Enable the USART clock (RCC) 2. Enable the NVIC controller 3. Configure the GPIO correctly 4. Enable the USART "USART_InitTypeDef" contents properly 4. Ensure you have the ISRs implemented
P.S. I tried to supply code, but it was too long to accept: verbose.
P.P.S. Forum improvement: allow for attachments? or would that be really hard to do?
Hi readers,
I also posted on the http://www.st.com forum which finally helped me out. It turned out that I had to enable the Alternate Function clock but beneath that I made an and/or error setting the stopbits making all bits in register CR2 being set. But now: it runs!
Thanks everyone.
We are all happy that my advise helped.
Burp.
Of course i meant advice.
Of course i meant i'm an idiot.