Having played around with the Arduino, I wanted to expand my knowledge by digging into the heart of Arduino's: Atmel's AVR MCUs.

In general, differences between the two are how it's programmed. The Arduino makes it easily accessible to utilize tools without having to deal with the underlying hardware (using the C++ language), like the AVR (using a version of C: avr-gcc) does.

The goal of this small project is to document my learning experience. This projects utilizes a simplex (one way) UART communication between two AVR MCUs: ATMega328P and the ATTiny85

The ATmega is bootloaded with MiniCore, this will be used as a transmitter (TX).

The ATTiny85 is bootloaded with TinyCore, this as a receiver (RX).

• Both the ATMega and ATTiny is provided a 3.3V power supply.

• The transmitter is hooked up to two push buttons, and OLED display and a LED indicator to simply display the status of whether the LED is turned on or off. This action sends an 8-bit binary number.

• The receiver is also hooked up to an OLED to show the data sent. An LED is wired to the data pin of the OLED and will light up.

(Schematic down below)

• +3.3V power supply
• 6 pin ISP programmer
• ATMega328P
• ATTiny85
• SH1106 128x64 I2C OLED
• SSD1306 128x64 SPI OLED
• 16 MHz crystal oscillator
• 10K ohm resistors - x3
• 680 ohm resistor
• 22pF capacitor - x2
• 0.1uF capacitor - x3
• Red LED
• Blue LED
• Tactile push buttons - x2

(Resistors on RESET pins of the MCUs must be pulled to LOW (GND) when programming, HIGH (VCC) after programming)

• MiniCore
• TinyCore
• Technoblogy's ATTiny's Terminal code
• U8G2 Graphics for OLED
• avr-libc

(Makefile included, this will include how to specifically compile the U8G2 library)

• I was not able to fully understand the code of Technoblogy's terminal and so I had set out to produce a minimal example. For now however, this is may be able to explain the idea.