ESP8266 Community Forum

- Wed Nov 30, 2016 5:58 pm #58921

Would it be an issue to reassign I2C to GPIO00 and 02, as they are pulled up during boot?

Not at all, those pins a perfect fit since they have already the pull-ups.
(I'm using I2C with those pins for almost 2 years)

Perfect! So I updated my schematic a bit, and finding my way around KiCAD (going to be the first board I have designed)

Updated Schematic:

ESP12E_Schematic.PNG

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- Wed Nov 30, 2016 9:43 pm #58923 I would put a lot more capacitance on VCC. at least 100uF but preferably higher.

- Thu Dec 01, 2016 5:53 am #58934

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?

- Thu Dec 01, 2016 9:48 am #58944

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.