Please be to review my ESP8266

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Everyone needs a projects review at sometime. Let us help each other with it. Schematic / Layout / C / C++

JarrettJarrett 03/27/2018 at 20:264 Comments

This has all the bells and whistles, so it'd be nice to get some more eyes on it.

It's exported from Upverter, which to be honest, I'm not particularly happy with the exported schematic view. The schematic looks decent within the tool, but as you can see, it's kinda terrible when viewed here!

Other than that, I quite like Upverter.

It's an ESP8266 dev board.

 USB-UART bridge uses DTR and RTS to control the programming pins, NodeMCU-style.

Battery or USB, whichever is higher, feed the main voltage input. That goes to a SMPS, which a fixed 3.3v output, and an enable pin tied to a low-voltage cut-off for when the battery sags to around 2.8v.

USB power is also feeding a battery charger.

Thoughts? Suggestions?

Most of the semiconductors are also ones that are available through AliExpress, which to me, means the Chinese clone market is using them and they should remain cheap/good/available, and easy to scale up if I want to manufacture.

Manufacturing and board bring-up postmortem:

(Excuse the terrible soldering, it was bodged a whole bunch of times as I was adding and taking things out of the circuit)

Most of the board works really well! USB enumerates and can program, the battery charges and works, the ESP8266 works.

A few issues that I missed, and need to be corrected:


Kris Winer wrote 03/27/2018 at 21:48 point

Is this a native ESP8266 IC or the ESP8266-mod12F module?

Cap on en, though not needed, should be 100 nF is you want to smooth the transitions. 10 uF is overkill.

Do you need the ESP8266 (if a native IC)? Maybe the ESP8285 would be a better choice with 1 MByte embedded flash. Much simpler design.

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Jarrett wrote 03/27/2018 at 22:13 point

I'm using the ESP12-F module. The bare ESP8285 chips aren't really cheaper than the modules, and they add in another level of complexity that I really don't care about for this test board.

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Kris Winer wrote 03/27/2018 at 21:35 point

Don't need a cap on ESP8266 En, and I would use a 10 K resistor for the pullup. I guess you are using an ESP8266 module so you don;t need the pull down on GPIO15 or pullups on GPIO 0 and 2?

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Jarrett wrote 03/27/2018 at 21:40 point

The cap on EN is for soft-starting it so I don't overload my power supply. Shouldn't hurt to leave it in.

I'll change the pull-up to 10k, and add the GPIO ones - I changed to this module from an ESP32, so I missed those, thanks!

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