larva_bb is the design variant targeting the Lattice iCE40 UltraPlus breakout board.
Please note that you must remove the "ICECLK" jumper, J51, before trying to download the design. If you don't, apparently the unprogrammed FPGA loads the clock to the point that the FTDI UART stops working during a download. This then causes Diamond Programmer to lock up, and even causes nasty driver problems leading to kernel crashes.
Check the project Kicad repository for wiring information at the system level. Pin assignments can be found in larva_bb_pcf_sbt.pcf in this directory.
The RPI UART cable should be connected to J3 (HEADER C) as follows:
| J3 Pin | Cable Pin | Function |
|---|---|---|
| 19 | Black | Ground |
| 17 | Orange | RX data (input to FPGA) |
| 15 | Yellow | TX data (output from FPGA) |
The UART transmits at 230,400 baud.
You should set your terminal emulator to treat linefeed (\n) as CR/LF.
Test with the cxx_test1 sample app. Build the FPGA, then launch a Larva Cygwin terminal. Change to the top of the development tree (i.e., above the fpga and sdk directories), and enter the following command to build the images.
for t in free checked ; do make LMIC_CFG_region=2 -C fpga/sw/cxx_test/software PROJECT_FPGA=larva_bb MDP_SERIAL=
1000 BUILDTYPE=$t -j4 clean || break ; done
for t in free checked ; do make LMIC_CFG_region=2 -C fpga/sw/cxx_test/software PROJECT_FPGA=larva_bb MDP_SERIAL=
1000 BUILDTYPE=$t -j4 || break ; doneIn other words, first clean, then build. The clean is needed to make sure that the PROJECT_FPGA=larva_bb setting really takes effect.