First Principles of Hardware Protocols

1. Read an unfamiliar protocol specification in a day and know what to look for.

2. Explain the reason behind the main design choices of AXI, PCIe, I2C, DDR, CHI, Ethernet, USB and UCIe.

3. Size buffers, credits, tags and replay windows from bandwidth and latency.

4. Debug a hang, a lost transfer or a throughput collapse from a waveform by reasoning about the protocol.

5. Answer senior and principal interview questions that have no single-protocol answer, and design a small protocol from requirements.

Each lesson carries its lowest level badge, and every lesson ends its teaching with a Senior or Principal lens, so experienced readers get something from the foundation pages too. See reading paths for routes by role.

• One picture that keeps coming back. A sender, a channel and a receiver with a return path. Each part adds its idea to that same figure: a ready signal, a credit counter, a replay buffer.

• DCLink, a protocol you build. Twelve steps across the course turn a bare wire into a small protocol with handshakes, credits, transactions, tags, ordering, arbitration, deadlock freedom, replay, start-up and low power.

• Real simulations. Every waveform comes from a simulation of the code on the page, and every number in a plot comes from a model on the page.

• Real protocols as evidence. Each lesson shows how two to four real protocols answered its question, and why their constraints led there.

Related topics