Minimal running picorv32 for CMOD S7

This is a personal proyect just to get down to basics and understand how the picorv32 is handled.

Goals!

I want to have a simple program to blink the leds in the board using the soft core. I want the soft core to be programmed via C/C++ and the FOSS toolchain.

Learn as much as possible!

• Including memory mapping layouts in the GCC compiler.
• KISS Keep it stupid simple!
• I want to use this proyect as basis for all my other fpga + picorv32 implementation.

New goals!!!!

Have the picorv32 communicate via SERIAL/UART to the computer as to allow basic communication/debug.

• I understand that this DOES NOT imply proper debugging, that would be through GDB.
• Serial decided for the time being to be provided by: jakubcabal/uart-for-fpga

Have the picorv32 communicate via SERIAL/UART and handle the reception via IRQ.

• This is a basis to handle all other kind of IO to not require POLLING.

Migrate to autotools for the software compilation.

• After serial I will focus on GDB debugging included into the system.

Completed goals!

I want to have a simple program to blink the leds in the board using the soft core.

• Done, it was very direct and insightful into how actual computers work.
  • TAG: "WorkingLeds".

I want the soft core to be programmed via C/C++ and the FOSS toolchain.

• Managed to cross compile from my ARM system, very happy about that one.
• Needed to compile from source to have all libraries be in RV32I configuration.

Have the picorv32 communicate via SERIAL/UART to the computer as to allow basic communication/debug.

• Currently is only sending data from PicoRV32 to the outside system.
• This is now working bidirectional with the example code of the PicoRV32 project.
  • TAG: "WorkingSerial".

Have the picorv32 communicate via SERIAL/UART and handle the reception via IRQ.

• The code is a bit bulkier, there is a buffer in the UART of 8 words deep, configurable by the user. In another update I will try to remove the buffer.
  • TAG: "WorkinSerialIRQ".
• Redone in a simplified logic, this follows more closely to the intentions of this GIT/proyect.
  • TAG: "WorkingSerialIRQSimplified"

Migration to autotools for software compilation done!

• This has a new README.md in software explaining high level functionality.
  • The core has been solved, allowing anyone take the files and just change their source code specific needs. It has all the configuration and files needed for this project linked.
    • TAG: "WorkingAutotools"

Produce a better system for understanding the status of the serial by the CPU.

• This has been accomplished, it was already given by DIN_RDY if it was kept high.
  • TAG: "WorkingSerialWait".

Aknowledgments

Absolutely to the picorv32 proyect, from which the main code is based on.

All the specifics regarding the board cmod S7.

Links

• Picorv32: https://github.com/YosysHQ/picorv32
• Cmod S7: https://digilent.com/reference/programmable-logic/cmod-s7/start
• RISC-V GNU Compiler Toolchain: https://github.com/riscv-collab/riscv-gnu-toolchain
• Verilog formatter: https://github.com/chipsalliance/verible
• Serial for FPGA: https://github.com/jakubcabal/uart-for-fpga.git