[STM32F072] USART2 and USART4 does not work

louis2 · ‎2014-04-10

Posted on April 10, 2014 at 13:50

Hello all,

I'm recently bought an STM32F072B-DISCO board (based on the STM32F072RBT6) and I'm currently testing it.

I'm really surprised to see that some USARTs doesn't work properly ; as mentioned in the errata sheet only USART4 has problem, but I noticed some problems on the USART2 and on the USART4.

Tests made separately on each USARTs

- USART1 :

TX = PA9 ; RX = PA10 => Fully functional

-USART2 :

TX = PA2 ; RX = PA3 => It doesn't work (no TX and no RX)

TX = PA2 ; RX = PA15 => Tx doesn't work, RX works

TX = PA14 ; RX = PA3 => Tx works, RX doesn't work (but no possibility to debug due to PA14 = SWCLK)

TX = PA14 ; RX = PA15 => Fully functional (but no possibility to debug due to PA14 = SWCLK)

- USART3 :

TX = PB10 ; RX = PB11 => Fully functional

- USART4 :

TX = PA0 ; RX = PA1 => TX doesn't work, RX works

TX = PA0 ; RX = PC11 => It doesn't work (no TX and no RX)

TX = PC10 ; RX = PA1 => Fully functional

TX = PC10 ; RX = PC11 => TX works, RX doesn't work (see errata sheet)

Does anybody has the same problem ? This could exclude a software problem on my USARTs libraries... (please note that I used them on STM32F051 MCU and there was no problem).

@ST Team : The STM32F07x are new in production, do their USARTs have a stable behavior ? Do some of these have a specific configurations to use ?

Thanks a lot,

Louis

#usart2 #stm32f07 #usart4

frankmeyer9 · ‎2014-04-10

Posted on April 10, 2014 at 14:17

Apart from possible issues in the software, it would not hurt to look at the board schematics before complaining about broken functionality.

Some pins might be routed to touch control, for instance, and not be usable for other purposes without some hardware changes.

Tesla DeLorean · ‎2014-04-10

Posted on April 10, 2014 at 15:28

Here's the

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/user_manual/DM00099401.pdf

you should be looking at.

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louis2 · ‎2014-04-10

Posted on April 10, 2014 at 15:42

Hello fm,

You're right, the problem was a hardware problem, I disconnected the touch sensor on the discovery board (by desoldering some resistors and capacitors) and I soldered some jumpers on PA2 / PA3.

Now all USARTs works perfectely, and without any modifications in my libraries !

This is really a newbie mistake... Okay I get out ! 😉

Thanks again,

Louis