- Tue Dec 13, 2005 10:19 am
#8546
I'm interfacing a CP210x USB/USART (or FT232R) to a PIC16F877A. I need to run the PIC at 5V and the datasheet says the TX and RX lines of the PIC are schmitt triggered with min Vh of 4V. It looks to me that this won't work with 3.3V logic.
I think I can just use a +5V pull-up on the PIC inputs but that has implications on max speed. I've not been able to find any info on this topic. I'd prefer not to use a logic shifter chip. If that's the case, then I'll probably use the FT232R since that seems to work better with 5V cmos logic levels. Anyone been there? what did you do?
I noticed that SFE breakout (for the cp2103, basically the same chip in this regard) doesn't do anything with the serial I/O lines. Am I worrying about a non-issue?
Phil
I think I can just use a +5V pull-up on the PIC inputs but that has implications on max speed. I've not been able to find any info on this topic. I'd prefer not to use a logic shifter chip. If that's the case, then I'll probably use the FT232R since that seems to work better with 5V cmos logic levels. Anyone been there? what did you do?
I noticed that SFE breakout (for the cp2103, basically the same chip in this regard) doesn't do anything with the serial I/O lines. Am I worrying about a non-issue?
Phil