I2C Timing & Arbitration · protocols

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Interface ProtocolsAll levels

4topics
4lessons

What you'll learn

I2C is two wires, open-drain, and deceptively simple — timing violations cause silent failures.

Open-drain: SDA and SCL pulled high, devices pull low. Pull-up resistor sizing matters.
START/STOP conditions, ACK/NACK, 7-bit or 10-bit addressing.
Clock stretching and multi-controller arbitration require explicit controller support and timeout policy.

Connection

Simplest serial protocol — illustrates timing contracts between RTL, board, and firmware.

Key diagram

One-byte combined register read

One-byte combined register read. Chosen target contract with one-byte register pointer and one-byte result. ACK ownership changes when the controller becomes the data receiver.

Chosen target contract with one-byte register pointer and one-byte result. ACK ownership changes when the controller becomes the data receiver.

Check yourself Who produces the final data-byte NACK in this successful read?

The controller, because it is receiving the final byte and intentionally ends the read.

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