ESP8266 Community Forum

Just an observation, I had my ESP8266 module powered from what I thought was a Micrel MIC2920-3.3 (a 3.3V/400mA LDO) and a 0.1uF capacitor across the 3.3V. I had a lot of communication problems (the commands were not echoed properly) and "busy" problems particularly when doing a survey (AT+CWLAP), so I put the scope on the supply rail. The LDO was clearly dropping out of regulation and the voltage dropping around 2V or lower for 200-300uS, I suspect that was when the module was transmitting RF. I added a 4.7uF capacitor across the 3.3V, which improved things significantly (communication errors went away) but the voltage was still dropping appreciably. I added a 470uF capacitor and now the 3.3V is perfectly stable. After doing all this, I checked the regulator which actually turned out to be a Linear Technology LT1121 which is only rated 150mA. Of course, if I had checked that first, I probably would not have had problems, but the significant part is that the "busy" problems are gone too (at least for now). For those who have been having random "busy" issues, I suggest checking the supply voltage and if in doubt, more decoupling cannot hurt.

Didier

Thanks for the info. Not that I have that problem... I am using one of those cheap DC-DC regulators from the internet LM2596 (I believe) adjusted at 3.3V. Oversized? absolutely... but no power problems.

Nice find!

Thanks for sharing!

Richard.

Yes, A 300 mA/3.3V power supply is definitely required, as well as at least a 10 µF decoupling capacitor as close as possible to the module, especially if you have long power cables.

As far as I can see, all the "busy" or reboot problems observed on this forum are related to weak / undersized decoupled power supplies.

Onboard decoupling on the ESP-01 is only using a small 100 nF capacitor, although the Espressif reference schematics recommend adding another 10 µF in parallel, thus the value above.