I am not capable of designing board layouts, maybe someone is keen on providing (and open-source) board designs for a ESP-WROOM-02 based board with a full or half pyboard foorprint?
The ESP-WROOM-02 is similar to the AI-Thinker ESP-Modules and seems to be Esspressif's own most recent incarnation of ESP8266 modules. It can be purchased for quite low price tag (~4 €), has it's own RF shield and 16MByte flash module.
I could think of some bare-metal features around this module like:
- All GPIOs exposed to the "full pyboard" footprint, important ones to a half one
- Jumper or button for the entering UART mode for flashing the ESP
- Jumper to connect GPIO16 to RST to enable deepsleep wakeups
- Jumper and voltage divider (high ohm resistors + cap) to connect VIN to the ADC (TOUT pin)
- Power supply only micro-USB port with an efficient 3v3 step-down converter (NO USB-serial chip)
- Serial port accessible by attching the USB-TTL, which nearly every ESP developer does own, to the exposed pins
Basically it should look somehow like this dirty draft (actual proportions should somewhat match): The further demands for the missing features of such a board could be answered by more half-pyboard-footprint addons (shield/hats/<you-name-it>) like:
- A real USB-TTL adapter board
- A fully fledged LiPo charger board
Why stuff all these features onto the main board when the final embedded device on the field does not sue it anymore? We have the fantastic pyboard as THE development board already!
Things like battery connector and LiPo charging circuitry is a waste on the ESP imho anyways, because of it's quite high power constraints. Only a few months on battery does not provide enough low-power capabilities imho. A step down converter with a wide input voltage range (4-12v) is more interesting.
TBH, i do not have any clue about parts to be used in this puppy!
edit: a small addition to the above: It would be nice to just provide the files for a double-sided PCB board, which everyone could order on pcb manufacturing sites like OSH-Park or others.