On 1/13/23 10:34, Jonathan Sturges via vcf-midatlantic wrote:

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Reset sees a low (/RST) every 3s. So there is a watchdog timer setup. I traced it back to a MC14584B (yea!) which is a hex schmidt trigger (what? 😉 ). So I have to do some more tracing but the MC14584B is socketed so I'll build a manual reset circuit and figure out what is going on later.

Ahh, the Schmidt trigger. Pairs of those gates are good for fixing marginal amplitude issues and/or "squarifying" a less-than-square waveform. If the RST signal looks well-formed, then the problem is probably upstream of the Schmidt trigger.

I pop'd the chip out and soldered up a resistor, cap and NO PB on a carrier. I'll search for the watchdog later. That solves that problem for now. The new troublemaker is the USB dongle doesn't have enough oomph to pull up the 6803 Rx pin. I'm going to drive it with either a NOT or NAND gates or an opto to drive it a bit more. -- Linux Home Automation Neil Cherry kd2zrq@linuxha.com http://www.linuxha.com/ Main site http://linuxha.blogspot.com/ My HA Blog Author of: Linux Smart Homes For Dummies KD2ZRQ