16 MHz, 2 KB Flash — the low-pin-count workhorse for sensor and control tasks
The device integrates a 4-channel 10-bit ADC, I²C/SPI via the USI module, and internal oscillator, so a minimal system needs only decoupling caps and a supply.
128 bytes RAM — design the stack budget early
The 128-byte RAM is the tightest resource on this part. A typical firmware task — reading the ADC, formatting a byte over I²C, and sleeping — fits, but adding a large lookup table or deep function-call nesting will overflow. Plan the stack size at the start of the project and use the Flash for constant data. The 2 KB Flash (2K x 8 plus 256 bytes) is enough for a modest state machine and calibration constants.
4-channel 10-bit ADC and serial connectivity
The integrated 10-bit ADC with four multiplexed channels reads analog sensors — thermistors, photodiodes, potentiometers — directly, eliminating an external converter. The USI module supports both I²C and SPI, so the part can talk to digital sensors, EEPROMs, or small displays. With only 4 general-purpose I/O pins, every pin carries multiple functions; the pin assignment must be checked against the peripheral mix during layout.