I'm designing a custom module with an ESP8266 associated with an USB microcontroller (MKL26Z32VFT4). The idea is to use the USB microcontroller to easily program the ESP8266 and to be able to use the multiple interfaces of the KL26 from the ESP8266.
The communication between the two processor is though SPI and through Serial from easy programming. With this configuration we get plenty of interfaces out of the box :
- 16 bits ADC with multiples inputs
- 12bits DAC
- serial interfaces
- Fast PWM
- Capacitive touch sensing
- Generic I/Os
Low power operation with a DC/DC converter for 3.3V (5V input) and 32kHz oscillator on the KL26. It is possible to put the ESP8266 in reset and wait for a long time before waking it.
The module has two 5V outputs to drive directly LED as WS2812 or APA102.
Pinout for the module :
and the schematic is in attachment.
I'm making this module for my own needs, but I think it can be useful for others. I'd be glad to have comment and ideas on the design, PCB is nearly finished, size is 30mmx47mm.