The most used microcontroller in our lab is the Attiny series including attiny44 and attiny45, another micro controller that our lab recently received is the Atmel SAMD21.
| MCU | Attiny44 | SAMD21 |
| RAM | 256 B | 16 KB |
| Flash | 4 KB | 128 KB |
| Byte size | 8 bits | 32 bits |
| Communication | SPI, I2C | UART, SPI, I2C |
| Pins | 14 | 48 |
| Voltage |
2.7 - 5.5V |
2.7 - 3.6V |
The main difference between the two is that the SAMD21 uses 3.3V while the Attiny uses 5v as operating voltage, another big difference is that the SAMD21 can have a bootloader which would allows us to reprogram it using serial connection.