sp193
commented
3 years ago @ludionisio's post helped me to compile libloragw and run the UDP Packet Forwarder with a modern Raspbian image. Thanks. The complete discussion was here at raspberrypi/linux#3749. I would like to add on, with some of my own observations.
The new kernel will claim GPIO7 (SPI0 CS1) if SPI is enabled, but IMO this only really blocks the reset procedure. Communication with the board may fail, due to it not getting reset. If ./reset_lgw.sh start is executed:
pi@raspberrypi:~/lora_gateway $ ./reset_lgw.sh start
Accessing concentrator reset pin through GPIO7...
./reset_lgw.sh: 27: echo: echo: I/O error
./reset_lgw.sh: 30: ./reset_lgw.sh: cannot create /sys/class/gpio/gpio7/direction: Directory nonexistent
./reset_lgw.sh: 33: ./reset_lgw.sh: cannot create /sys/class/gpio/gpio7/value: Directory nonexistent
./reset_lgw.sh: 34: ./reset_lgw.sh: cannot create /sys/class/gpio/gpio7/value: Directory nonexistent
./reset_lgw.sh: 37: ./reset_lgw.sh: cannot create /sys/class/gpio/gpio7/direction: Directory nonexistentThe "I/O Error" is actually EBUSY (Device or resource busy), due to the kernel already reserving GPIO7 and making it impossible to export GPIO7 in /sys/class/gpio. A possible solution would be to remap at least CS1 of SPI0, by adding an overlay to /boot/config.txt.
I also found that it is important to keep CS0 as GPIO8, as the reference board (and compatibles) uses this. libloragw accesses /dev/spidev0.0 by default, which refers to CS0 of SPI0.
If the board is not enabled, reads over SPI may result in 0s getting read.
The Semtech starter kit also uses some GPIO pins for the LCD panel. From /opt/lora-net/misc/lcd.py:
# Raspberry Pi pin configuration:
lcd_rs = 25 # original 27 # Note this might need to be changed to 21 flor older revision Pi's.
lcd_en = 24 # original 22
lcd_d4 = 23 # original 25
lcd_d5 = 17 # original 24
lcd_d6 = 27 # original 23
lcd_d7 = 22 # original 18
lcd_backlight = 4I believe it is better to use GPIO5 instead of 25.
gatismu
A recent update of the kernel of Raspberry Pis changed the Device Tree Overlay setting for the SPI and enabled by default the Chip Select Pins 7 and 8.
The shown error is:
ERROR: Failed to load fw 1ERROR: Version of calibration firmware not expected, actual:0 expected:2ERROR: [main] failed to start the concentratorIn order to continue using these Raspberry Pi Hats that follow the reference design, which use GPIO 7 for resetting the concentrator it is now necessary to add the following line to the
/boot/config.txt:dtoverlay=spi0-cs,cs1_pin=25(make sure there are no spaces)This directive reroutes Chip Select 1 to GPIO 25, you may also use another free GPIO if your setup requires so.