Tamagotchi-like embedded device. As bare metal as possible.

To setup avr-gcc:

1. brew tap osx-cross/avr
2. brew install avr-gcc

To setup avrdude:

1. brew install avrdude

Check program size and memory usage:

avr-size build/main.elf

Make note of the $(PORT) definition, this is the USB port the MCU is plugged into. So this value will need to change depending on where it's plugged in. Use the Arudio IDE to identify the /dev path

I have included in docs/ the following:

• ATMega328P datasheet
• AVR architecture instruction set manual
• Pinout of the Arduino Nano clone board im using for prototyping
• Fritzing project file (very early WIP)

Links:

• EInk Display Product Page
• OLED Display Product Page

Datasheet notes:

• PRSPI bit may need to 0 to enable SPI, but this may only be for USART>SPI control...
• SPI master inits comm cycle when slave-select pin is pulled low
  • Then master/slave prepare packet data in shift registers
  • Master generates required SCK signal
• After each data packet, master syncs slave by pulling SS high
• No automatic control of SS when master
• Writing byte to SPI DR starts SCK generator, then 8 bits shifted to slave
  • After shifting 1 byte, SCK generator stops and sets EOT flag in SPIF
• Request interrupt by setting SPIE bit in SPCR
• Continue to shift more bytes, or if done, signal end of packet with SS high
  • Last byte is kept in buffer register for later
• Single buffer for transmit as master, must wait for shift cycle to complete before next byte in SPDR