The ATtinyx4 has several clock options, including an internal clock that runs at 128kHz, or an RC clock that runs
8MHz along with a divide by 8 fuse. The maximum frequency is 20MHz with an external crystal.
The default is 8MHz divided by 8, or 1MHz. The fuse sets the divisor at reset time - you can change the divisor
programmatically at any time.
Power Supply vs. Maximum Frequency
The maximum clock frequency is dependent on the power supply voltage, and the calculator below can help you
determine the maximum clock frequency at any power supply voltage.
Maximum Frequency Calculator for ATtiny24/44/84
|I/O Pins ||12|
|ADC Channels ||8|
|RT Counter (w/osc)||0|
|Timers (8-bit) ||1|
|Timers (16-bit) ||1|
|PWM (8-bit) ||2|
|PWM (16-bit) ||2|
|Price (1's) ||$1.14||$1.30||$1.41|
|Power Consumption (approximate) ||1mA + (0.58mA/MHz)|
|Maximum I/O Current (per pin) ||40mA|
|Maximum I/O Current (all ports) ||100mA|
|Maximum I/O Current (total) ||200mA|
Link to ATtiny24/44/84 datasheet from Atmel's website.
ATtiny24/44/84 "Minimal" Circuit Diagram
The circuit below shows a programming port, reset circuit, and a crystal oscillator. Any or all of these could be
left off and the device would function perfectly well.