Best place to add decoupling capacitors??

userHead roykayser 2020-02-05 01:29:21 3114 Views3 Replies
We are running some custom firmware written in C++ on our LattePanda VER 1 (DFR0418) and love it so far. I am using an FTDI 4 channel USB to RS232 PCB to control 4 x RS232 enabled devices. We are using the FIT0477 display with FIT0478 touch panel. Our firmware runs fine in the lab and we have 26 machines running. At our customer site we are seeing RS232 disconnect issues, screen freeze issues and other issues.

I suspect there may be excessive noise on our +5V 3A power supply and want to add decoupling capacitors to test this theory. I will also be testing a better power supply (medical grade with lower ripple and noise). Note we cannot duplicate the problem in our lab.

For testing purposes I want to add some low ESR decoupling capacitors to the LattePanda. Which connector is it best to add these caps to?
The 3 position connectors housing D9-D11 & A0 to A2?
CN2?
We have a ribbon cable occupying all of the 24 pin dual row header.

Any other ideas?

Thanks.