modelI2c

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Electrical I2C bus (open drain, 100 kHz) between two MCU blocks: SCL and SDA are shared by both boards and only rise through the two 4.7 kΩ pull-up resistors, as on a real bus. Board A (i2c_controller.py) is the controller (machine.I2C); board B (i2c_target_mem.py) is a target at address 0x42 (machine.I2CTarget) that exposes a bytearray as a memory: it needs no handler, the library answers the controller on its own while the program of B only keeps the memory up to date.

Register map of B: bytes 0-1 = last ADC reading of its GP2 (2 V here), byte 4 = its LED. A scans the bus (it finds 0x42), writes 1 to register 4 (writeto_mem: ledB lights up), reads back registers 0-1 (readfrom_mem) and prints the voltage measured by B; its GP7 goes high if everything is right. Variant where B answers from an IRQ handler: Examples.MultiMcu.I2cIrq.

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