Opentherm Gateway no longer responding

[mlies]

Not sure what happened but my gateway is no longer responding to commands.

I have it hooked up via a level changer to an esp8266 running ESP-Link (serial to wifi) with opentherm monitor running on my server in the other room.

I disconnected the esp and hooked up my laptop directly to the OTGW board with an ftdi-style cable. Doesn't work either. Definitely worked that way when I originally put the thing together last month.

Also tested for continuity between the header pins and the pin on the chip, that checks out as well..

I think I may have destroyed the PIC's uart with static discharge or something, but I'm not sure.

Anyone have a good idea for diagnosing this other than buying a replacement PIC and going through the woes of getting that one flashed? Because I'm running out of ideas

[hvxl]

There's an easy way to check if the PIC is working. When you power up the gateway you should see the LEDs flash briefly. If you don't, either your PIC is not working correctly, or you forgot to connect the LEDs.

[mlies]

Oops, sorry for never responding!

It took me a while but I managed to find the problem, it's a rather silly one as it turns out...

On booting, the ESP spits out a bunch of diagnostic stuff on a weird baud rate, which confuses the PIC. What complicated matters is that apparently, the PIC remains confused when connecting a USB TTL cable and hitting reset.

It can be solved by using different GPIO pins on the ESP for the UART communication with the gateway. Or worked-around* by disconnecting the TX cable, powercycling the thing, and then reconnecting.

It's been working reliably for months now

*) I admit, this is what I'm currently doing.

[antst]

Just in case, if someone hit the same issue, you can solve it without power cycling. Just reset OTGW.

In my case, I run ESP8266-transparent-bridge on ESP8266, and connected GPIO2 to RST. If it got confused after boot, I just cycle state of GPIO2 with AT command of ESP firmware and it works.
Although, I'd prefer to have device which goes 100% online after power cycle without human touch. This can be achieved by modifying ESP firmware to do automatic cycle on GPIO after boot, to ensure that OTGW starts after ESP.