This folder is step20 of the popular FPGA tutorial "From Blinker to RISCV" by BrunoLevy.
Step20 demonstrates the creation of a separate native RISC-V assembly program, and how run it from the FPGA BRAM. Two example programs are saved in the subfolders src-blink and src-hello. By default, 'make' builds the src-blink' assembly program that simply blinks the onboard LED's. By using 'make hello', the second example program is built, which writes a "Hello World!" string to the UART.
fm@nuc7fpga:~/fpga/projects/git/gatemate-riscv/step20$ make
make -C src-blink
make[1]: Entering directory '/mnt/hgfs/fpga/projects/git/gatemate-riscv/step20/src-blink'
...
/home/fm/fpga/projects/git/gatemate-riscv/riscv-toolchain/firmware_words/firmware_words blinker.bram.elf -ram 6144 -max_addr 6144 -out firmware.hex
RAM SIZE=6144
LOAD ELF: blinker.bram.elf
max address=162
Code size: 40 words ( total RAM size: 1536 words )
Occupancy: 2%
testing MAX_ADDR limit: 6144
max_addr OK
SAVE HEX: firmware.hex
make[1]: Leaving directory '/mnt/hgfs/fpga/projects/git/gatemate-riscv/step20/src-blink'
cp src-blink/firmware.hex .
/home/fm/cc-toolchain-linux/bin/yosys/yosys -p 'read -sv SOC.v ../rtl-shared/clockworks.v ../rtl-shared/pll_gatemate.v ../rtl-shared/emmitter_uart.v; synth_gatemate -top SOC -vlog SOC_synth.v'
/----------------------------------------------------------------------------\
| |
| yosys -- Yosys Open SYnthesis Suite |
| |
| Copyright (C) 2012 - 2020 Claire Xenia Wolf <claire@yosyshq.com> |
...
=== SOC ===
Number of wires: 590
Number of wire bits: 3187
Number of public wires: 67
Number of public wire bits: 1041
Number of memories: 0
Number of memory bits: 0
Number of processes: 0
Number of cells: 1214
CC_ADDF 170
CC_BRAM_20K 5
CC_BUFG 1
CC_DFF 106
CC_IBUF 3
CC_LUT1 37
CC_LUT2 50
CC_LUT3 388
CC_LUT4 444
CC_OBUF 9
CC_PLL 1
...
End of script. Logfile hash: d5749ba093, CPU: user 0.73s system 1.07s, MEM: 29.90 MB peak
Yosys 0.29+42 (git sha1 2004a9ff4, g++ 12.2.1 -Os)
Time spent: 30% 1x abc (0 sec), 14% 28x opt_expr (0 sec), ...
test -e ../gatemate-e1.ccf || exit
/home/fm/cc-toolchain-linux/bin/p_r/p_r -i SOC_synth.v -o SOC -ccf ../gatemate-e1.ccf +uCIO > SOC_pr.log
fm@nuc7fpga:~/fpga/projects/git/gatemate-riscv/step20$ make test
Running testbench simulation
test ! -e SOC.tb || rm SOC.tb
test ! -e SOC.vcd || rm SOC.vcd
/usr/bin/iverilog -DBENCH -o SOC.tb -s SOC_tb SOC_tb.v SOC.v ../rtl-shared/clockworks.v ../rtl-shared/pll_gatemate.v ../rtl-shared/emmitter_uart.v
/usr/bin/vvp SOC.tb
LEDS = 111xxxxx
LEDS = 11110101
LEDS = 11111010
LEDS = 11110101
LEDS = 11111010
LEDS = 11110101
LEDS = 11111010
LEDS = 11110101
LEDS = 11111010
^C** VVP Stop(0) **
** Flushing output streams.
** Current simulation time is 37906102 ticks.
> finish
** Continue **
step20$ make prog
Programming E1 SPI Config:
/home/fm/cc-toolchain-linux/bin/openFPGALoader/openFPGALoader -b gatemate_evb_spi SOC_00.cfg
Jtag frequency : requested 6.00MHz -> real 6.00MHz
Detail:
Jedec ID : c2
memory type : 28
memory capacity : 17
EDID + CFD length : c2
EDID : 1728
CFD :
00
Detail:
Jedec ID : c2
memory type : 28
memory capacity : 17
EDID + CFD length : c2
EDID : 1728
CFD :
flash chip unknown: use basic protection detection
Erasing: [==================================================] 100.00%
Done
Writing: [==================================================] 100.00%
Done
Wait for CFG_DONE DONE
With the UART assigned to the E1 boards PMODB connector pins, the Digilent PMOD-UART converter receives the RISC-V program output, and we can display it in a terminal window. The terminal output runs at a bitrate of 833.333, falling short of the UART target speed of 1Mbaud (1.000.000). The root cause is discussed in Issue #3. Setting the GTKTerm port speed to baudrate 800.000 is sufficient.
