Associate III

Question

Problem on USART

Forum|Forum|9 years ago
March 5, 2017
20 replies
3144 views

Posted on March 05, 2017 at 19:53

Hi,

I'm working on STM32F091 MCU fora the first time and I'm trying to test the USART1 on PF0,1. I have just wrote the code and it works well, but now I can't receive the RXNE interrupt.. the tx line works normally.. if I try to set the port as an input I see the correct logic level on pin so the port works, it seems that the shift register of USART NOT WORK. Any idea?

Thanks.

lorenzo.

This topic has been closed for replies.

Tesla DeLorean

Guru

Posted on March 05, 2017 at 20:35

>>Any idea?

Show the code, and indicate what model of STM32F091 specifically you are using, and that has USART1 on PF0 and PF1

http://www.st.com/content/ccc/resource/technical/document/datasheet/95/3c/2e/5b/21/09/45/a6/DM00115237.pdf/files/DM00115237.pdf/jcr:content/translations/en.DM00115237.pdf

Both TX, and RX pins should be configured in AF mode, and muxed correctly.

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Selso LIBERADO

Associate II

Posted on March 06, 2017 at 13:57

Hello !

did you actually use the STMCube firmware, did you you STMCubeMX to configure your pins ?

did you check that the IRQ is enabled ?

It's actually hard to give an answer without any code information ?

lorenzo meneghelloAuthor

Associate III

Posted on March 07, 2017 at 21:34

Thanks for the reply!

The code is very simple just configure the pin and the speed like ST example, the code works. I've connected the STM with the Max232 but is supplied with 5V.. it maybe the problem?

Tesla DeLorean

Guru

Posted on March 07, 2017 at 22:16

A MAX3232 would be more appropriate. I suspect most pins are 5V tolerant at this point, but check the Data Sheet.

What part / board are you using. Give all the digits of the part number so I can at least correlate your PF0 and PF1 pining to some part supporting the USART there.

>>

The code is very simple just configure the pin and the speed like ST example, the code works.

Let me judge the validity of the code, cause you're complaining it is not working, so something is wrong with your logic at some level.

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lorenzo meneghelloAuthor

Associate III

Posted on March 08, 2017 at 09:21

I'm using the STM32F091RBT6 on my board, and the USART1 port are PA9&PA10.

This is the code:

void UsartInit (void) {

RCC->APB2ENR |= RCC_APB2ENR_USART1EN; // enable clock for Alternate Function

GPIOA->MODER |= 0x280000;

GPIOA->AFR[1] |= 0x110;

GPIOA->OSPEEDR |= 0x300000; //PA10

USART1->BRR = 0x1388; // set baudrate 9600BAUD

USART1->CR1 |= (USART_CR1_RE | USART_CR1_TE);

NVIC_EnableIRQ(USART1_IRQn);

USART1->CR1 |= USART_CR1_UE; // USART enable

USART1->CR1 |= USART_CR1_RXNEIE;

}

The TX line works and also the RX line has worked but now it van't receive the RXNEIE interrupt.. if I enable the IDLE line interrupt I receive the interrupt so the interrupt configuration works.

Thanks.

Lorenzo.

lorenzo meneghelloAuthor

Associate III

Posted on March 14, 2017 at 12:00

Any other idea? Thanks.

Tesla DeLorean

Guru

Posted on March 14, 2017 at 13:27

Not really much to work with here, kind of hard to debug through the keyhole.

Perhaps present some diagnostic/analysis you've done, like plots from a scope or logic analyzer. Schematic for the circuit.

Perhaps you have a colleague who can review things with you or try other known working code/hardware.

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lorenzo meneghelloAuthor

Associate III

Posted on March 22, 2017 at 17:05

Hi all,

2 weeks that I'm trying to comunicate with this UART.. Now I've a new news! If found that if I disable the TE bit I can receive from the PC... Any idea?

Thanks.

Tesla DeLorean

Guru

Posted on March 23, 2017 at 01:26

Perhaps there is some language difficultly here, I've asked for specific things, I've provided some example code, and you're still playing this 'guess what's wrong game'.

Present the problem so someone on the other side of the Atlantic can review the code and hardware you are working with. If you spend 20-30 mins doing this you might be able to see the problem for yourself.

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