ESP8266 Community Forum

- Tue May 05, 2015 7:52 am #16552 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

esp8266_bb.jpg

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- Tue May 05, 2015 8:19 am #16555 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

- Tue May 05, 2015 9:16 am #16564

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?

- Tue May 05, 2015 10:47 am #16582 this setup runs perfectly with a raspberry pi. so i think the wiring is ok