chipKIT® Development Platform

Inspired by Arduino™

Hardware buffer HCT244/HCT245 on inputs/outputs?

Created Wed, 06 Jun 2012 06:59:57 +0000 by Demolishun


Wed, 06 Jun 2012 06:59:57 +0000

I have a system built and it seems to work fine. I have inputs coming from TTL sources, and outputs going to TTL. Both incoming and outgoing TTL are 5V. I also have made it so all my inputs / outputs to TTL use 5V tolerant pins just to be hopefully a little more robust. The problem is I am concerned about one device in particular. When it gets reset I think it may be causing my Uno32 that is connected to it to reset. I don't know how, but it might be noise dumped on the ground? I don't know yet. Maybe I just answered my own question.

I was thinking about putting a HCT245 buffer on the outputs to see if this helps, but after thinking through this the device would still dump noise on the ground. So maybe I need to consider some power supply filtering to see if it helps. I don't know, I am not sure I can reproduce this either. Since I made some code changes it is now acting a lot more stable than before. I know it sounds strange, but those changes controlled the Reset signal sent to the device. At one point I think I was putting the device in constant reset, so maybe it was causing the TTL to go out of spec or doing some nasty things to the ground. :?