Coap server on esp8266 esp-12 using bus-pirate as tool for flashing.
steps:
- Install picocom:
sudo apt-get install picocom

- Give permissons to tty
sudo chmod 666 /dev/ttyUSB0:

- Access bus pirate:
picocom -b 115200 /dev/ttyUSB0

- Configure pirate as UART bridge (on images attached you can see a 3 steps image)

* Hit m key
HiZ>m
* Select uart mode:
3. UART
* Set serial port speed: (bps)
9. 115200
* set default data bits and parity:
1. 8, NONE *default
* Set default stop bits:
1. 1 *default
* Set default receive polarity:
1. Idle 1 *default
* Select output type:
2. Normal (H=3.3V, L=GND)
* Now you are on UART mode
* Turn on power supply
UART>W
* Select transparent bridge
UART>(1)

- After this Follow the PCB diagram image attached, there is 2 modes flashing and boot.
when s2 and s3 are set you can flash otherwise you can boot the device, also after each mode switch to set reset s4.

next: follow github link.
(still in progress)