iothing wrote:Hey, I can now also add to the not working list: ferrite core around the leads to the esp module.
The problem with inductive loads is not when they run, but if they are powered off. My module always reboots when the relay switches off. To reduce EMI I put an snubber on the relais C and NO terminals so that the peak at the switchoff is reduced. I use a X2 capacitor .23uF in Series with a 56Ohm 3W resistor. This mitigates the problem with crackling/popping sounds in the stereo and relay contact burnoff/welding together. Moving the esp away did not help because it is coupled to the relais board by the wires - I guess.
Actually cutting the RST trace helped most so far, but the problem is: if the module crashes, it takes ages to reboot and as the rst is not there anymore I cannot reboot it via the arduino (heartbeat check). Also how can RST be pulled up when the trace is cut? Someone wrote there is an internal pullup - is this really the case?! What pins have internal pullups on the esp01? Can the pullup be controlled by the software?
Yes, this looks/sounds like conducted EMI, and there are strong indications that the RST line has an unfortunate layout on the module, making it sensitive.
Some very experienced users here have reported not having seen these problems at all, while others report very persistent problems. So maybe there are production batch differences? One thing that it could be interesting to check is whether the internal pullup on the RST line is sufficiently strong.
A hypothesis could be that it is too weak, and thereby causes the problem if the module layout is poor. But in that case, hardwiring RST to VCC shuold help; apparently it does not.
The ESPs are reportedly very sensitive to Vcc stability. Have you looked over your Vcc/GND layout to eliminate any ground loops you may have?