minimalist breadboard friendly breakout for esp12-e
After many more tweaks, I've sent it for fab.
Here is how it looks now.
Now I'm very happy with the board layout. The mount holes are placed where they should be i.e on corners. Routed the board and ready for production.
Removed level converters. Added a linear regulator 1117-3v3.
Keeping it simple. I use a CP2102 board for programming. Adding a programmer is redundant as after development its useless.
I might switch to a switching regulator but not at this stage. I'd get some samples and test out this pcb first.
oh yeah also added a power on led as esp is going to be upside down, it good to know if board powered.
Added bi-directional 3v3 to 5v converter using popular BSS138 mosfets. Added a voltage divider on ADC, so that is also 5V tolerant. The accuracy of ADC measurements will depend on the resistor accuracy, it can be taken care of in software using a calibration routine.
There is a lot of real estate on the board, its logical to add in a usb -usart chip. I'd use CP2102, as I use it for all my projects and its a excellent option. Its running in one of my project since 2 years which is powered 24x7.
I'm still not settled on the power supply section, I've thrown in a 1117 to get 3v3. Ideal solution would be to use a switching regulator, so it can be used with battery powered applications.
I think I'll have to make a trade off between choosing the USB-usart chip and a switching regulator.
The board has a lot of un used space, which can be used for adding some features.
I got some good suggestions and spotted some my mistakes as well.
Here are the features I'm adding now.
1. Fliping the switches so legends are visible during prototyping.
2. Re position the mount holes.
3. Add bi-directional 3v3 to 5v level conversion on board so 5v devices and be easily be interfaced.
4. Removing the 6 pin header that connects to internal flash