ESP8266 Community Forum

- Thu Dec 01, 2016 3:35 pm #58963

I would put a lot more capacitance on VCC. at least 100uF but preferably higher.

I am a bit confused here. In my understanding, the ceramic 100nF serves as a decoupling cap correct?
If I already have a reservoir cap from the supply section, do I still require another reservoir near the module?

And how much charge is available from a .1uF cap? Where did you get the idea that that was sufficient? Yes a decent sized cap in your power supply is good to have but how close will it be?

The ESP8266 (and many other devices like this) have some high current draws at time. They will cause a dip in the supply voltage. And what we need to do is to make that dip/spike smaller than what the ESP8266 and the flash chip will consider as a disruption.

One thing you should remember. Every wire is an inductor. Every trace is an inductor. Every via has inductance. For many things we can ignore these but sometime they do matter.

Thanks for the clear explanation, makes sense. Sorry for the somewhat basic questions, but now I know what to read up about, and determine the right way to determine what value of buffer capacitance to provide. Lots to learn for me!

- Thu Dec 01, 2016 6:55 pm #58971 Most people don't know how touchy some of this stuff can be. When I first started to play with the Arduino boards I saw what many people were doing, bad practices, and they were getting away with it for the most part. The thing about the processors used in low end Arduino boards, they don't use a lot of current. They run at low clock speeds.

WiFi based chips are a whole different animal. Less forgiving. I have seen some information about the current requirements for the ESP8266 that imply 200mA is all you need. And that might be on a long term average but when the WiFi transmit happens the peak currents are higher. Expressif has something in their FAQ on the part that says the peak current for the analog output is 350mA and 200mA for digital circuitry. But on startup the Analog can draw 500mA. That's pretty significant.

- Fri Dec 02, 2016 8:16 am #59006 Hi, someone else will comment but I didn't think that GPIOs 9 & 10 could be used on a standard ESP8266-12x with out disconnecting them from the flash IC which is not easy the screening can needs to be removed.

- Mon Dec 05, 2016 7:07 am #59124

Hi, someone else will comment but I didn't think that GPIOs 9 & 10 could be used on a standard ESP8266-12x with out disconnecting them from the flash IC which is not easy the screening can needs to be removed.

I realise that and did update my schematics, didn't upload them here yet though!
PS: This would be the way to go about it if you really needed it: http://smarpl.com/content/esp8266-esp-2 ... and-gpio10