Supported Features (APB3/APB4)

APB3

• Master driver: setup/access sequencing, optional drop/continuous style (drop_psel_between)
• Slave responder: simple word-addressed memory model
• Optional wait-state insertion (min_wait_cycles, max_wait_cycles)
• Optional error injection (PSLVERR) by address range + probability
• Monitor: transaction reconstruction on completion cycle and analysis port broadcast
• Scoreboard: expected memory model + read data check (optional)

APB4 (APB3 + extras)

• PPROT generation/checking (optional randomization)
• PSTRB generation/checking (optional randomization)
• Byte-lane masked writes in slave memory model (PSTRB applied)
• APB4-only assertion gating when +APB_PROTOCOL=APB4

Multi-select (PSEL[NSEL-1:0])

• Interface supports vector PSEL with NSEL parameter.
• Master selects sel_index (defaults to 0).

Runtime protocol mode switch

• Single interface includes APB4 signals always.
• Use +APB_PROTOCOL=APB3|APB4 (default APB4).

Limitations (current)

• Slave model is a simple memory (not a full register model). It is intended as a robust demo/reference and for integration smoke checks.
• No “negative/bad-driver” mode tests yet; assertion toggles exist for bring-up.