stm32l053 usart2 levels

[lee23]

Posted on May 27, 2015 at 23:22

As you can see here:

https://drive.google.com/file/d/0B979a_DgADKmNkE4N1B0R21BaXM/view?usp=sharing

I'm trying to send data out USART2; it seems to be set up correctly and outputting to pin A14, but the voltage levels don't make sense. It's marking high at 3.3v like it should, but low (space) is over 2v, nowhere near 0. Am I doing something wrong?Must be some setting of the chip, because when I do a hard power-down reset, the problem goes away. Maybe some piece of code on the discovery board is setting something.

[Tesla DeLorean]

Posted on May 28, 2015 at 00:43

The PA14 pin is the debug interface's clock pin, it's driven by the DISCO's ST-LINK chip.

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/user_manual/DM00118944.pdf

[lee23]

Posted on May 28, 2015 at 17:46

Ah, thanks. Then won't be a problem in production. Looks like A2/A3 are used by the touch sensor, so similar issue there.