Olimex Support Forum

Others => UEXT => Topic started by: pculverhouse@gmail.com on May 25, 2020, 02:15:39 pm

Title: STM32-E407 UEXT RS232 voltage compatibilty
Post by: pculverhouse@gmail.com on May 25, 2020, 02:15:39 pm
Hi,

I am wanting to make my own UEXT USART6 i/o to USB. I am using the FDTI FT234XD (USB TO BASIC UART IC). I can see serial output from the UEXT using my 'scope. And I can plug the USB into a computer and it is seen as a tty.USB0 from Linux, for example.

But I cannot transfer data. I am wondering if I need a level translator between the UEXT TX/RX pins and the FDTI FT234xd chip? I cannot see why I need this, since both chips operate at 5v.

Any ideas?
regards
Phil
Title: Re: STM32-E407 UEXT RS232 voltage compatibilty
Post by: LubOlimex on May 26, 2020, 09:30:48 am
The STM32F407 chip in STM32-E407 design is powered by 3.3V and this makes the UART pins 3.3V too. I recommend you to measure the voltage levels with your scope to confirm it.
Title: Re: STM32-E407 UEXT RS232 voltage compatibilty
Post by: pculverhouse@gmail.com on May 27, 2020, 11:15:53 am
Thanks!

I had an earthing problem. All solved.

Regards

Phil