This PCBA connects widely available LoRa modules based on Semtech SX127x RFIC, such as this module (archive) sold on Aliexpress for less than $3, to the Texas Instruments BeagleBone family of single board computers.
The module must have a size of 16 by 16 mm, and have 16 castellated pads with 2 mm spacing; for details, see the Kicad footprint. The module pinout must match the following, viewed from the top:
| Pin 1? | ||
|---|---|---|
| ANT | GND | |
| GND | DIO5 | |
| DIO3 | nRESET | |
| DIO4 | nCS | |
| 3V3 | SCK | |
| DIO0 | MOSI | |
| DIO1 | MISO | |
| DIO2 | GND |
These modules do not have a clearly marked pin 1, so the actual pinout may be rotated 180° compared to the above.
See also the bill of materials.
The following table lists the BeagleBone pins and their connections:
| Radio# | Function | BB pin | CPU pin |
|---|---|---|---|
| radio0 | nRESET | P9_15 | gpio1[16] |
| radio0 | IRQ | P9_16 | gpio1[19] |
| radio0 | nCS | P9_17 | gpio0[5] |
| radio0 | SCK | P9_22 | gpio0[2] |
| radio0 | MOSI | P9_18 | gpio0[4] |
| radio0 | MISO | P9_21 | gpio0[3] |
| radio1 | nRESET | P9_25 | gpio3[21] |
| radio1 | IRQ | P9_27 | gpio3[19] |
| radio1 | nCS | P9_28 | gpio3[17] |
| radio1 | SCK | P9_31 | gpio3[14] |
| radio1 | MOSI | P9_30 | gpio3[16] |
| radio1 | MISO | P9_29 | gpio3[15] |
Radio 0 is connected to CS0 of SPI0, radio 1 is connected to CS0 of SPI1.
To configure BeagleBone pins, run the following commands:
sudo modprobe spidev
sudo chown $USER /dev/spidev*
config-pin P9_15 gpio_pu
config-pin P9_16 gpio_pu
config-pin P9_17 spi_cs
config-pin P9_22 spi_sclk
config-pin P9_18 spi
config-pin P9_21 spi
config-pin P9_25 gpio_pu
config-pin P9_27 gpio_pu
config-pin P9_28 spi_cs
config-pin P9_31 spi_sclk
config-pin P9_30 spi
config-pin P9_29 spiThese commands were tested on Debian 12 (bookworm).
To perform a basic test of module functionality, install spi-tools and run the following commands:
echo '0: 4200' | xxd -r | spi-pipe -b 2 -d /dev/spidev0.0 | xxd
echo '0: 4200' | xxd -r | spi-pipe -b 2 -d /dev/spidev1.0 | xxdBoth commands should return the following output:
00000000: 0012 ..
The number 12 is the module ASIC revision.
Steps for performing a full test of module functionality, including radio transmission and reception, will be provided later.
A1 : Initial revision
The adapter is covered by the CERN-OHL-P (permissive) license. See LICENSE.txt for details.