because I asked myself what the price would be in case I use the PIzero and want to create a shield... tada:

This is a design for an arduino HAT that can feature an atmega328p as a cheap ADC and even more IOs I don't use. Arduino for real-timey-wimey stuff. I've completely done it the wrong way again, first designed, then checked. Still had some fun and assures me that it's doable.

Path to do:

1. check how much current the 3.3V power converter on the raspi can deliver additionally for powering the arduino
   1. if needed, design a power supply based on the MCP1710 (shutdown input makes it interesting for arduino)
2. add 5V micro/mini USB port and put ACS712 between
3. add RGB LED for basic debugging (wsb2812 or plain rgb)
4. add jumpers / soldering connections for different powering setups
5. maybe replace the quartz for something SMDish

http://pi.gadgetoid.com/article/building-the-pico-piduino

https://projects.drogon.net/raspberry-pi/gertboard/arduino-ide-installation-isp/

http://pinout.xyz/pinout/arduino_spi

433MHz remote control

https://github.com/r10r/rcswitch-pi