Spectravel - Spectrometer on Caravel

Block diagram of the Spectravel is given below and detailed explanation of the each block is given inside submodules spectrometer and wb2axip.

This directory contains following submodules and directories:

• Submodule spectrometer - contains digital spectrometer generator with built in test structures designed in Chisel HDL
• Submodule wb2axip - contains wishbone to AXI4 bridge. Current submodule is forked version of the ZipCPU/wb2axip
• doc - contains global block scheme of the Spectravel block in svg and png format.
• top/dv/SpectrometerTest - contains verilog testbenches for Spectravel integrated with Caravel
• top/rtl/SpectrometerTest - contains user_proj_example.v which is the top level verilog file for Spectravel
• Makefile - have targets for verilog and test generation

Verilog generation and Chisel tests

Before running make commands, we could set the size of FFT inside spectrometer. Default size is 128. For example, we could set the size of the FFT inside spectrometer to be equal to 256 with the command:

$ export SIZE=256

To run verilog generation and Chisel tests, sbt and verilator must be installed. For installation details see this link.

In order to generate verilog file SpectrometerTest.v which contains verilog code for digital spectrometer, run command:

$ make verilog_spectrometer

To run chisel tests for digital spectrometer, run command:

$ make test_spectrometer

Verilog tests

In order to run verilog tests for Spectravel connected to Caravel, PDK_ROOT and RISCV32 paths must be set. RISCV32 is path to RV32I Toolchain. For RV32I toolchain installation click here. To check if paths are set, run command:

$ make check-env

Currently there are four different tests for Spectravel connected to Caravel:

• plfg_nco_fft_mag_acc_utx - Data path is: PLFG -> NCO -> FFT -> MAG -> ACC -> uTx (UART output)
• plfg_nco_fft_mag_acc_pout - Data path is: PLFG -> NCO -> FFT -> MAG -> ACC -> outStream (8b AXI4-Stream)
• pin_nco_fft_mag_acc_pout - Data path is: inStream (8b AXI4-Stream) -> NCO -> FFT -> MAG -> ACC -> outStream (8b AXI4-Stream)
• pin_fft_mag_acc_pout - Data path is: inStream (8b AXI4-Stream) -> FFT -> MAG -> ACC -> outStream (8b AXI4-Stream)

All tests contain C code where appropriate Spectravel registers are set in order to obtain desired functionality. Output of the Spectravel is compared with golden model generated with Chisel. In order for test to pass, Spectravel output data must be the same as golden model data.

By default, caravel_spectrometer repository contains all data needed to run verilog tests. Thus, verilog tests can be run without installing sbt.

In order to test Spectravel added to the Caravel, run command:

$ make test_top

To clean data generated by verilog testbenches, run:

$ make clean_top

In order to regenerate verilog code, run chisel tests and run Spectravel tests, run command:

$ make run_all

Address space for Spectravel

User address space 0x3000_0000
    ├── in_split:   0x3000_0000
    ├── plfg_ram:   0x3000_1000
    ├── plfg:       0x3000_2100
    ├── plfg_split: 0x3000_2200
    ├── plfg_mux_0: 0x3000_2210
    ├── plfg_mux_1: 0x3000_2220
    ├── nco:        0x3000_3000
    ├── nco_split:  0x3000_3100
    ├── nco_mux_0:  0x3000_3110
    ├── nco_mux_1:  0x3000_3120
    ├── fft:        0x3000_4000
    ├── fft_split:  0x3000_4100
    ├── fft_mux_0   0x3000_4110
    ├── fft_mux_1:  0x3000_4120
    ├── mag:        0x3000_5000
    ├── mag_split:  0x3000_5100
    ├── mag_mux_0:  0x3000_5110
    ├── mag_mux_1:  0x3000_5120
    ├── acc_queue:  0x3000_6000
    ├── acc:        0x3000_7000
    ├── out_mux:    0x3000_8000
    ├── out_split:  0x3000_8010
    ├── uart:       0x3000_9000
    └── uart_split: 0x3000_9100