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Simulator

ATtiny85 simulator, chip and breadboard together

Mokxi is a free ATtiny85 simulator that runs in your browser, with nothing to install and no account needed. Push the chip into the breadboard, wire its two rails, write the sketch, press Run. Mokxi models an ATtiny85 down to the tinyAVR instruction set it actually has, and it is a load on your supply rather than a board that brings its own.

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ATtiny85: blinklive0.000 s 0.00x
Click to open it in the editor
Real firmware, running right now on our own core. Click it to open the circuit in the editor.
What is modeled

The numbers, not the marketing

Taken from the board's own contract document and put in plain words.

The core
The tinyAVR instruction set on the internal 8 MHz oscillator, with the datasheet cycle count of every instruction. There is no MUL, no JMP and no CALL on this part, and there is none here either: reaching for one stops the chip and says which opcode it was.
Peripherals
Port B with its pull-ups, timer 0 in all four waveform modes, the high-speed timer 1 with OCR1C as TOP, a four-channel ADC with both internal references, the USI, INT0 and the pin-change interrupt, 512 bytes of EEPROM and sleep.
Power and serial
The chip is a load, not a supply: wire 5 V to pin 8 and ground to pin 4, and its logic levels and ADC reference follow whatever you gave it. There is no USART, so Serial is bit-banged on PB3 and PB4 and the monitor reads those two pins.
Go further

The full board page

Every peripheral area, every example and the wiring notes, in one place.

ATtiny85 simulatorBlink, a button and the serial monitor, running.

Questions

Which ATtiny does this simulate?

The ATtiny85, in the eight-pin DIP package.

Why does nothing happen until I wire the supply?

Because it is a chip, not a board. Unpowered it is high-impedance on every pin and does nothing, which is what an ATtiny85 on a breadboard with no rails does.

How does the serial monitor work without a USART?

The firmware bit-bangs 8N1 on PB3 and PB4, and the simulator watches those pins the way a USB-serial adapter clipped to them would. It costs real time: about a millisecond a byte at 9600 baud.

Is it free?

Yes, all of it, with no card and no account needed to try it.

Try your own firmware on the ATtiny85

What you build here runs on the board on your desk, unchanged. Nothing to install and no account needed.

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