ESP8266 Community Forum

I am using a esp8266 breakout with a uln2003a to drive a 2 channel opto isolated relay. When i wire it as per the fritzing sketch the esp8266 does not start. only when i remove the jumper wire from gpio 2 pin does the esp8266 boots. if i plug the jumper wire on the gpio 2 pin after the esp8266 had started i can operate the relay perfectly but when i plug the jumper wire before esp8266 has booted the esp won’t start.
guidance needed


Thanks

If gpio2 or gpio0 are held low (even "weakly") by external circuit then ESP boots in un-useful mode, I think that is what is happening.

So, try putting a 1k to 4k pull-up resistor from gpio2 to +3.3v

Cheers,
John

rajbadri wrote:I am using a esp8266 breakout with a uln2003a to drive a 2 channel opto isolated relay. When i wire it as per the fritzing sketch the esp8266 does not start. only when i remove the jumper wire from gpio 2 pin does the esp8266 boots. if i plug the jumper wire on the gpio 2 pin after the esp8266 had started i can operate the relay perfectly but when i plug the jumper wire before esp8266 has booted the esp won’t start.
guidance needed


Thanks

Is your ULN2003 wired correctly?

this setup runs perfectly with a raspberry pi. so i think the wiring is ok