If you have a raspberry PI around, you can use the flashrom utility with Linux’ /dev/spidev to program a bitstream to your ICE40HX1K-EVB. The following table shows the wiring required for the Pi B+ or 2. I used IDC connectors with a rainbow ribbon for convenient wiring (image below).
| Raspi 2/B+ | ICE40-EVB | comment | ||
|---|---|---|---|---|
| 17 | 3v3 | 1 | 3v3 | |
| 18 | gpio24 | 6 | creset | |
| 19 | mosi | 8 | sdo | |
| 20 | gnd | 2 | gnd | |
| 21 | miso | 7 | sdi | |
| 22 | gpio25 | 5 | cdone | optional |
| 23 | clk | 9 | sck | |
| 24 | ce0 | 10 | #cd = ss_b | |
| 25 | gnd | |||
| 26 | ce1 |
enable SPI device on the Pi (needs reboot)
echo dtparam=spi=on >> /boot/config.txt
build and install flashrom
git clone https://www.flashrom.org/git/flashrom.git cd flashrom make CONFIG_ENABLE_LIBPCI_PROGRAMMERS=no CONFIG_ENABLE_LIBUSB0_PROGRAMMERS=no CONFIG_ENABLE_LIBUSB1_PROGRAMMERS=no install
claim GPIO24 for sysfs-control
echo 24 > /sys/class/gpio/export
Pull GPIO24 low to put the ice40 into reset. The cdone-LED on the board should turn off.
echo out > /sys/class/gpio/gpio24/direction
Read the flash chip at 20MHz (for short cabling)
flashrom -p linux_spi:dev=/dev/spidev0.0,spispeed=20000 -r dump
Simply swap -r for -w to write the dump back
flashrom -p linux_spi:dev=/dev/spidev0.0,spispeed=20000 -w dump
As generated bitstreams are smaller than size of the flash chip, you need to add padding for flashrom to accept them as image. I used the follwing commands to do that:
tr '\0' '\377' < /dev/zero | dd bs=2M count=1 of=image dd if=my_bitstream conv=notrunc of=image
Deassert creset to let the ice40 read the configuration from the bus:
echo in > /sys/class/gpio/gpio24/direction
