Board pin maps

This page maps Arduino pin numbers and peripheral signals to the simulator properties you use to observe or drive them from your tests.

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Arduino Uno (ATmega328P)

Preset class: ArduinoUnoSimulation
Properties: PortB, PortC, PortD, Timer0, Timer1, Timer2, Serial, Eeprom

Digital pins → GPIO port

Arduino pin	AVR port	Pin index	Simulator property	Notes
0	PortD	0	uno.PortD pin 0	USART0 RX
1	PortD	1	uno.PortD pin 1	USART0 TX
2	PortD	2	uno.PortD pin 2	INT0
3	PortD	3	uno.PortD pin 3	INT1, OC2B
4	PortD	4	uno.PortD pin 4
5	PortD	5	uno.PortD pin 5	OC0B
6	PortD	6	uno.PortD pin 6	OC0A
7	PortD	7	uno.PortD pin 7
8	PortB	0	uno.PortB pin 0
9	PortB	1	uno.PortB pin 1	OC1A
10	PortB	2	uno.PortB pin 2	OC1B, SS
11	PortB	3	uno.PortB pin 3	MOSI, OC2A
12	PortB	4	uno.PortB pin 4	MISO
13	PortB	5	uno.PortB pin 5	SCK, LED_BUILTIN

Analog pins → ADC / GPIO

Arduino pin	AVR port	Pin index	ADC channel	Simulator property
A0	PortC	0	0	uno.PortC pin 0
A1	PortC	1	1	uno.PortC pin 1
A2	PortC	2	2	uno.PortC pin 2
A3	PortC	3	3	uno.PortC pin 3
A4	PortC	4	4	uno.PortC pin 4
A5	PortC	5	5	uno.PortC pin 5

Serial → USART

Arduino Serial object	USART	Simulator property
Serial	USART0	uno.Serial

Common assertions

uno.PortB.Should().HavePinHigh(5);          // LED_BUILTIN on
uno.PortD.Should().HavePinLow(3);           // INT1 pin low
uno.PortC.Should().HavePinInputPullup(4);   // A4 as pulled-up input
uno.Serial.Should().ContainLine("hello");

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Arduino Mega 2560 (ATmega2560)

Preset class: ArduinoMegaSimulation
Properties: PortA–PortL, Timer0–Timer5, Serial0–Serial3, Eeprom

Serial channels

Arduino Serial object	USART	TX pin	RX pin	Simulator property
Serial	USART0	1 (PE1)	0 (PE0)	mega.Serial0
Serial1	USART1	18 (PD3)	19 (PD2)	mega.Serial1
Serial2	USART2	16 (PH1)	17 (PH0)	mega.Serial2
Serial3	USART3	14 (PJ1)	15 (PJ0)	mega.Serial3

Selected digital pins → GPIO port

Arduino pin	AVR port	Pin	Simulator property	Notes
0	PortE	0	mega.PortE pin 0	RX0
1	PortE	1	mega.PortE pin 1	TX0
13	PortB	7	mega.PortB pin 7	LED_BUILTIN, SCK
14	PortJ	1	mega.PortJ pin 1	TX3
15	PortJ	0	mega.PortJ pin 0	RX3
16	PortH	1	mega.PortH pin 1	TX2
17	PortH	0	mega.PortH pin 0	RX2
18	PortD	3	mega.PortD pin 3	TX1
19	PortD	2	mega.PortD pin 2	RX1
20	PortD	1	mega.PortD pin 1	SDA
21	PortD	0	mega.PortD pin 0	SCL
22–29	PortA	0–7	mega.PortA pin 0–7
30–37	PortC	7–0	mega.PortC pin 7–0
42–49	PortL	7–0	mega.PortL pin 7–0
50	PortB	3	mega.PortB pin 3	MISO
51	PortB	2	mega.PortB pin 2	MOSI
52	PortB	1	mega.PortB pin 1	SCK
53	PortB	0	mega.PortB pin 0	SS

Analog pins → ADC / GPIO

Arduino pin	AVR port	Pin	ADC channel
A0–A7	PortF	0–7	0–7
A8–A15	PortK	0–7	8–15

Common assertions

mega.PortB.Should().HavePinHigh(7);          // LED_BUILTIN (digital 13)
mega.Serial0.Should().Contain("ready");
mega.Serial1.Should().ContainLine("ping");
mega.PortA.Should().HaveOutputValue(0xFF);   // all Port A pins high

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ATtiny85

Preset class: ATtiny85Simulation
Properties: PortB, Timer0, Timer1, Eeprom

The ATtiny85 has a single 6-pin I/O port (PB0–PB5; PB3 = RESET, disabled by default).

Physical pins → port

DIP8 pin	Signal	Port B pin	Simulator property	Notes
1	PB5 / RESET	5	tiny.PortB pin 5	RESET (fuse-dependent)
2	PB3 / ADC3	3	tiny.PortB pin 3	ADC3
3	PB4 / ADC2	4	tiny.PortB pin 4	ADC2, OC1B
5	PB0 / MOSI	0	tiny.PortB pin 0	USI DO, OC0A
6	PB1 / MISO	1	tiny.PortB pin 1	USI DI, OC0B, OC1A
7	PB2 / SCK	2	tiny.PortB pin 2	USI SCK, INT0

Common assertions

tiny.PortB.Should().HavePinHigh(1);   // PB1 (physical pin 6) driven high
tiny.PortB.Should().HavePinLow(0);    // PB0 (physical pin 5) driven low

Injecting a button press on INT0 (PB2)

// Drive PB2 low to simulate a button press (active-low)
tiny.PortB.SetPin(2, false);
tiny.RunMilliseconds(10);

// Release
tiny.PortB.SetPin(2, true);
tiny.RunUntilSerial(...);