SoftI2CPeripheral — Arduino Playground

Simulation test environment for the SoftI2CPeripheral library.

Two ATmega2560 firmware images (I2C controller + peripheral) run simultaneously inside pysimulavr, connected by simulated I2C and UART wires. This validates the library against a real software I2C master (SoftWire) without any hardware.

Prerequisites

• PlatformIO (to build the firmware)
• pysimulavr (pip install pysimulavr or build from source)

Build & run

pio run                    # build both environments
python avrsim_i2c.py       # run simulation (Ctrl+C to stop)

Common options:

python avrsim_i2c.py -n 5          # stop after 5 real-time seconds
python avrsim_i2c.py -i            # log every I2C SCL/SDA transition to stderr
python avrsim_i2c.py -i -n 0.3 2>&1 | head -80   # quick debug snapshot

Controller UART → stdout prefixed [CTRL] Peripheral UART → stderr prefixed [PERI]

Simulation wiring

Both devices are ATmega2560 running at 16 MHz. The simulated pins are connected via pysimulavr Net objects with explicit weak pull-ups.

Signal	Arduino pin	AVR port	simulavr key
SCL	21	PD0	"D0"
SDA	20	PD1	"D1"
UART TX	1	PE1	"E1"

Project layout

src/controller/main.cpp   — I2C master using SoftWire
src/peripheral/main.cpp   — I2C peripheral using SoftI2CPeripheral
lib/SoftI2CPeripheral/    — library submodule
avrsim_i2c.py             — dual-device simulation harness
platformio.ini            — two PlatformIO environments