README-WiringPi-64bit-OS.md

wiringPi as the low-level SPI library

In January 2021, we decided to provide support for next 64-bit OS. The main reason is to prepare the whole low-cost Raspberry-based gateway to embed advance AI frameworks that are mostly based on 64-bit OS. To do so, the low-level SPI library on the Raspberry has moved from Libelium's arduPi lib to Gordon's wiringPi lib because arduPi relies heavily on direct memory accesses that are difficult to port. Note that on 32-bit OS, arduPican still be used if you do not want to move to wiringPi.

What have been modified

• on 32-bit OS, the original wiringPi distribution, although not maintained anymore by the author, can be installed (http://wiringpi.com/). However, the 32-bit SD card image includes the modified wiringPi version, see below.

• on RPI4, even with 32-bit OS, it is necessary to get the unofficial Mirror/Fork from https://github.com/WiringPi/WiringPi to get wiringPi supporting the RPI4. However, both the 32-bit and 64-bit SD card images include the modified wiringPi version, see below.

• on 64-bit OS, the "UNOFICIAL WiringPi library for RPi 64bit OS" from https://github.com/TheNextLVL/wiringPi provided a solution but failed to run on an RPI4.

• finally, I merged the contributions from both https://github.com/WiringPi/WiringPi and https://github.com/TheNextLVL/wiringPi to get wiringPi supporting RPI4 and also running on 64-bit OS:

  • take this updated version https://github.com/CongducPham/LowCostLoRaGw/raw/master/zip/wiringPi-64bit-RPI4.tgz
    • wget https://github.com/CongducPham/LowCostLoRaGw/raw/master/zip/wiringPi-64bit-RPI4.tgz, then
    • tar xvfz wiringPi-64bit-RPI4.tgz
    • cd wiringPi-64bit-RPI4
    • sudo ./build

• while arduPi uses Arduino-like pin numbering, wiringPi has its own pin numbering system. See section on pin numbering below

• even with wiringPi, the SPI-related functions offered by arduPi (which mimicks those of the Arduino SPI lib) is still used as API. The objective is also to be able to compile on the Raspberry codes that are written in Arduino style, possibly even for Arduino platforms. In this way, it is easier to maintain almost the same source code for both platforms. Therefore, with wiringPi, arduinoPi.cpp is a wrapper to wiringPi SPI calls.

Compiling

• the makefile has been updated

  • use raspberry.makefile to indicate the SPI lib
    • SPILIB=ARDUPI | WIRINGPI
  • if there is a /boot/raspberry.makefile file, it will have priority
  • then make lora_gateway or
  • simply using the scripts/compile_lora_gw.sh script which is the recommended option

• on 32-bit OS, arduPican still be used

• for testing purposes, you can however manually compile for a specific target

  • with arduPi

  • make SX1272_lora_gateway or make SX1272_lora_gateway_pi2 or make SX1272_lora_gateway_pi2 (Libelium 1272/1276 lib)

    • make SX126X_lora_gateway or make SX126X_lora_gateway_pi2 or make SX126X_lora_gateway_pi4 (Stuart Robinson's SX12XX lib)

  • make SX127X_lora_gateway or make SX127X_lora_gateway_pi2 or make SX127X_lora_gateway_pi4 (Stuart Robinson's SX12XX lib)

  • make SX128X_lora_gateway or make SX128X_lora_gateway_pi2 or make SX128X_lora_gateway_pi4 (Stuart Robinson's SX12XX lib)

  • with wiringPi

    • make SX1272_lora_gateway_wiring (Libelium 1272/1276 lib)
    • make SX126X_lora_gateway_wiring (StuartProject's SX12XX lib)
    • make SX127X_lora_gateway_wiring (StuartProject's SX12XX lib)
    • make SX128X_lora_gateway_wiring (StuartProject's SX12XX lib)

Pin numbering with wiringPi

Remember that pin numbering now follows the wiringPi which is illustrated below. Be sure to indicate the pin number from "wPi" column when you identified on which physical pin you connected the various wires needed by the radio module

+-----+-----+---------+--B Plus--+---------+-----+-----+
| BCM | wPi |   Name  | Physical | Name    | wPi | BCM |
+-----+-----+---------+----++----+---------+-----+-----+
|     |     |    3.3v |  1 || 2  | 5v      |     |     |
|   2 |   8 |   SDA.1 |  3 || 4  | 5V      |     |     |
|   3 |   9 |   SCL.1 |  5 || 6  | 0v      |     |     |
|   4 |   7 | GPIO. 7 |  7 || 8  | TxD     | 15  | 14  |
|     |     |      0v |  9 || 10 | RxD     | 16  | 15  |
|  17 |   0 | GPIO. 0 | 11 || 12 | GPIO. 1 | 1   | 18  |
|  27 |   2 | GPIO. 2 | 13 || 14 | 0v      |     |     |
|  22 |   3 | GPIO. 3 | 15 || 16 | GPIO. 4 | 4   | 23  |
|     |     |    3.3v | 17 || 18 | GPIO. 5 | 5   | 24  |
|  10 |  12 |    MOSI | 19 || 20 | 0v      |     |     |
|   9 |  13 |    MISO | 21 || 22 | GPIO. 6 | 6   | 25  |
|  11 |  14 |    SCLK | 23 || 24 | CE0     | 10  | 8   |
|     |     |      0v | 25 || 26 | CE1     | 11  | 7   |
|   0 |  30 |   SDA.0 | 27 || 28 | SCL.0   | 31  | 1   |
|   5 |  21 | GPIO.21 | 29 || 30 | 0v      |     |     |
|   6 |  22 | GPIO.22 | 31 || 32 | GPIO.26 | 26  | 12  |
|  13 |  23 | GPIO.23 | 33 || 34 | 0v      |     |     |
|  19 |  24 | GPIO.24 | 35 || 36 | GPIO.27 | 27  | 16  |
|  26 |  25 | GPIO.25 | 37 || 38 | GPIO.28 | 28  | 20  |
|     |     |      0v | 39 || 40 | GPIO.29 | 29  | 21  |
+-----+-----+---------+----++----+---------+-----+-----+
| BCM | wPi |   Name  | Physical | Name    | wPi | BCM |
+-----+-----+---------+--B Plus--+---------+-----+-----+

• the wiring of NSS, NRESET, BUSY and DIO1 pins are defined in the SX126X_lora_gateway.h, SX127X_lora_gateway.h and SX128X_lora_gateway.h files. You can overwrite these definitions in radio.makefile: for instance -DNRESET=7. By default, the numbering still refers to the arduPi pin numbering system: NSS=10 (GPIO8), BUSY=5->GPIO25, NRESET=6->GPIO4, DIO1=2->GPIO18. If you move to wiringPi then indicate in radio.makefile:

  • -DNRESET=0 for WaziHat. Correspond to GPIO17
  • -DNRESET=7 for our radio module breakout. Correspond to GPIO4
  • -DRFBUSY=6 for our radio module breakout (SX1262 and SX1282). Correspond to GPIO25. Only needed for SX1262/SX1282
  • NSS can remain to 10 because wiringPi and arduPi has same number
  • e.g. CFLAGS+=-DNSS=10 -DNRESET=7 -DRFBUSY=6

Enjoy! C. Pham