Peripherals

Avr8Sharp emulates the ATmega/ATtiny peripheral set with datasheet-accurate register behaviour. All peripherals are optional and added through the AvrTestSimulation builder API (or wired up automatically by the board presets).

Coverage

Peripheral	Status	Notes
GPIO (I/O ports)	✅	Pin-change and external interrupts
USART	✅	Baud config, TX/RX, interrupts
Timer 0/2 (8-bit)	✅	Normal, CTC, Fast PWM, Phase-correct PWM
Timer 1/3/4/5 (16-bit)	✅	Normal, CTC, Fast PWM, Phase-correct PWM, Input Capture
ATtiny85 TC1 (8-bit)	🟡	Normal mode; CTC and PWM modes not emulated
SPI	✅	Master mode, SPSR/SPCR/SPDR
TWI (I²C)	✅	Master mode; slave state machine not emulated
ADC	✅	8 channels, single-conversion mode
EEPROM	✅	Read/write/erase, EE_RDY interrupt
USI	✅	Three-wire and two-wire mode
Watchdog	✅	Prescaler, reset, interrupt mode

For the mapping between Arduino pin numbers and simulator port/pin properties, see Board pin maps.

Note

Per-peripheral reference pages are being filled in. For now, the API surface is documented via XML-doc comments in the source; see Reference.

GPIO

All I/O ports expose AvrIoPort, which mirrors the hardware PIN/DDR/PORT triple:

// Drive PB5 high from the test host
uno.PortB.SetPin(5, true);

// Read firmware output
bool isHigh = uno.PortB.GetPinState(5);

// Register a listener for any pin change
uno.PortB.AddListener(pin => Console.WriteLine($"PB{pin} changed"));

USART

// Capture all TX bytes in a SerialProbe (done automatically by board presets)
sim.AddUsart(AvrUsart.Usart0Config, out var serial);
serial.OnByte = b => Console.Write((char)b);

// Inject a byte into the RX FIFO (simulates host → firmware)
serial.Usart.WriteByte(0x41);   // send 'A'

Timers

Timer peripherals fire output-compare events that toggle OC pins automatically. You can also hook the compare match callback:

sim.AddTimer(AvrTimer.Timer1Config, out var timer1);
timer1.OnOutputCompareMatch += channel => Console.WriteLine($"OC1{(char)('A' + channel)}");

EEPROM

sim.AddEeprom(AvrEeprom.EepromConfig, out var eeprom, eepromSize: 1024);

// Pre-load EEPROM content before running firmware
eeprom.Backend.Data[0] = 0xCA;
eeprom.Backend.Data[1] = 0xFE;

ADC

sim.AddAdc(AvrAdc.AdcConfig, out var adc);

// Set the voltage on channel 0 (in millivolts, 0–5000)
adc.ChannelValues[0] = 2500;   // 2.5 V → mid-scale