# Requirements & Functional Specification

## Requirements Specification

The aim of the project is the implementation of the Raspberry Pi's RP2040 programmable I/O state machine (PIO) in an FPGA to help understanding this instance and general forms of programmable state machines. Driving a 64x64 RGB LED matrix could be optional illustrations of the PIO capabilities.

![Hardware top level block diagram](res/SoC_PIO_Block_Diagram.svg)

## Functional Specification

- PIO original specification
- UART 

### Mandatory

- Compatibility to the Raspi PIO spec
  - Side-set
  - Program wrapping
  - Autopush and autopull
  - Clock dividers
  - Forced and `EXEC`’d instructions
  - Full instruction set `JMP`, `WAIT`, `IN`, `OUT`, `PUSH`, `PULL`, `MOV`, `IRQ`, `SET`
  - 4 state machines per PIO block

- 4 testing Programs
  - UART
  - SPI
  - Manchester encoded UART/Differential manchester (BMC) TX and RX
  - (I2C)

### Optional:

- FIFO joining
- Multiple PIO blocks
- Full GPIO mapping support
- Additional PIO functions for common tasks
  - CRC calculation
  - Stuff bit counter
- Same timing/performance capabilities within the possible frequency range of the FPGA
- Video output via 64x64 RGB LED matrix
- Language and compiler for PIO assembly