PicoRV32 has an optional co-processor interface. Including and exposing it in a future Caravel framework would enable the creation of new RISC-V extensions.

The co-processor interface, core signals to the user project ports. Not physical pins.

output        pcpi_valid

output [31:0] pcpi_insn

output [31:0] pcpi_rs1

output [31:0] pcpi_rs2

input         pcpi_wr

input  [31:0] pcpi_rd

input         pcpi_wait

input         pcpi_ready