| Specifications | ATtiny202 | ATtiny402 |
|---|---|---|
| Flash (program memory) | 2048 bytes | 4096 bytes |
| Flash w/Optiboot | 1536 bytes | 3584 bytes |
| RAM | 128 bytes | 256 bytes |
| EEPROM | 64 bytes | 128 bytes |
| Bootloader | No | No |
| GPIO Pins | 6 (5 usable) | 6 (5 usable) |
| ADC Channels | 6 (5 usable) | 6 (5 usable) |
| PWM Channels | 4 | 4 |
| Timer Type B | 1 | 1 |
| DAC | No | No |
| Interfaces | UART, SPI, I2C | UART, SPI, I2C |
| Clock options | Internal 16/20mhz | Internal 16/20mhz |
There exist ATtiny402's in the wild where the last byte of the signature is 0x25, instead of 0x27. Currently shipping parts from Atmel/Microchip have the correct signature, and this problem appears to be in the past, for the most part. Hoerver, if you're stuck with wrong-signature ATtiny402's ATtiny402 (bad signature) from the tools -> chip menu.