Digital Protocol Practice: UART, SPI, AXI, APB & I2C
Practice digital interface and protocol reasoning across UART, SPI, AXI ready/valid, AXI-Lite, APB and I2C arbitration.
What interviewers usually look for
Protocol questions test cycle-accurate sequencing, framing, handshake rules, backpressure, data stability, and the independence of channels or phases.
How to practise this topic
- Exercise the fastest legal transfer and a stalled or backpressured transfer.
- Check payload and control stability while a transfer is pending.
- Test transaction boundaries and back-to-back transfers.
Practice problems
UART Transmitter
Design an 8-N-1 UART transmitter.SPI Master
Implement a basic SPI mode-0 master for byte transfers.Backpressure-Safe Ready/Valid Source
Implement a source register that obeys ready/valid protocol semantics.APB Register Peripheral
Build a minimal APB peripheral exposing one 32-bit read/write register.AXI-Lite Write Register Slave
Implement the write side of a single-register AXI-Lite slave.
Design an 8-N-1 UART transmitter.SPI Master
Implement a basic SPI mode-0 master for byte transfers.Backpressure-Safe Ready/Valid Source
Implement a source register that obeys ready/valid protocol semantics.APB Register Peripheral
Build a minimal APB peripheral exposing one 32-bit read/write register.AXI-Lite Write Register Slave
Implement the write side of a single-register AXI-Lite slave.
How to use this topic
Start with easier problems, implement or reason through the task without looking at a solution, then revisit medium and hard problems. Use the HDLForge roadmap to combine this topic with adjacent skills.
Follow the HDLForge roadmap or browse the complete problem set.
Related implementation guides
- AXI-Lite Verification Guide — Learn how to verify AXI-Lite RTL with independent channel handshakes, assertions, scoreboards, backpressure tests and executable HDLForge practice.
- Ready/Valid Handshake RTL Guide — Design ready/valid RTL correctly with backpressure, payload stability, skid buffers, elastic pipelines and executable HDLForge practice problems.