This program is guided to help establish a connection between two RFM95 900MHz LoRa radio modules using Maxim Integrated's Feather MCUs (MAX32630FTHR Mbed and the MAX32620FTHR Mbed). Once the radios are configured after powering on and if the radios are wired correctly, the two radios will self identify as either a master or a slave, and will then proceed to PING and PONG back and forth. Information about what is happening between the radios can be seen if the two boards are hooked up to a USB COM port through the included DAPLINK modules.

Dependencies:   BMI160 BufferedSerial SX1276GenericLib USBDeviceHT max32630fthr

Fork of MAX326xxFTHR_LoRa_RFM95 by Central Applications - Mbed Code repo

RFM95 LoRa Example Ping Pong Program

Getting Started

This program has the support for sx1276 (Adafruit RFM95W LoRa Radio Transceiver Breakout - 900 MHz) and (Adafruit LoRa Radio FeatherWing - RFM95W 900 MHz) to work with a few different mbed boards (see PinMap.h for supported boards). However, this specific program is set up to work with the following mbed boards and RFM95 915MHz LoRa radios and the given pin diagrams without modifications: MAX32620FTHR and MAX32630FTHR.

Configuring the LoRa Radio

The setup for the radio can be found in <<SX1276GenericPingPong/GenericPingPong.cpp>>, which can be found by navigating from the root directory. Setup for the radio starts on line #14 in <<SX1276GenericPingPong/GenericPingPong.cpp>>.

Choosing the Correct Frequency

This program was written with libraries compatible with RFM95 LoRa 900MHz Radio modules. The radio's frequency is able to be tuned dynamically, however this program configures the frequency by programming registers at device power on. The 900MHz module supports both 868MHz and 915MHz operation. Check local laws for which band around 900MHz is set aside for the scientific, commercial, and/or license free usage in your country. The supported frequencies can be found in <<SX1276GenericLib.lib/sx1276/sx1276.h>>

They are also listed below for convenience:

SX1276GenericLib.lib/sx1276/sx1276.h

typedef enum {
    RF_FREQUENCY_868_0 = 868000000, //Hz
    RF_FREQUENCY_868_1 = 868100000, //Hz
    RF_FREQUENCY_868_3 = 868300000, //Hz
    RF_FREQUENCY_868_5 = 868500000, //Hz
    RF_FREQUENCY_915_0 = 915000000, //Hz
    RF_FREQUENCY_915_1 = 915100000, //Hz
    RF_FREQUENCY_915_3 = 915300000, //Hz
    RF_FREQUENCY_915_5 = 915500000, //Hz
} rf_frequency_t;

Please chose a supported frequency above that is compatible with your RFM95 (or likewise single band compatible sx1276 radio) module and change line #22 in <<SX1276GenericPingPong/GenericPingPong.cpp>> to the correct enum above.

Wiring

This program is aimed at working without modifications with RFM95W LoRa 900MHz modules in both a Breakout board and a FeatherWing version.

FeatherWing setup

This wiring diagram is useful if your RFM95W LoRa 900MHz module is a Feather wing made by Adafruit.

Before jumpers are soldered in:

/media/uploads/dev_alexander/feather_pinouts.jpg

After jumpers are soldered in:

/media/uploads/dev_alexander/rfm95_feather_pinouts_drawn_in.jpg

Note: The default pin configurations for the radio in this program (found in <<PinMap.h>> under targets MAX32630FTHR and MAX32630FTHR ) can be changed to suite additional modifications built from a fork of this program repo. If this is the case, the diagrams above will need to be changed to suite the new pin map.

For more information, a detailed wiring guide for the RFM95W Featherwing can be found here.

Breakout Board

For a breakout board, the following wiring diagram will work with both the MAX32630FTHR and the MAX32630FTHR mbed boards if wired in the same locations:

Before the RFM95W is connected with wires:

/media/uploads/dev_alexander/rfm95_breakout_pinouts.jpg

After the RFM95W is connected with wires:

/media/uploads/dev_alexander/rfm95_breakout_pinouts_drawn_in.jpg

The representations of the connections above can be found in<<PinName.h>> under targets MAX32630FTHR and MAX32630FTHR.

This default pin configuration will set you up with a connection to the MCU.

For more information, a detailed wiring guide for the RFM95W Brakout Board can be found here.

Antenna

Since this is radio communication, we are going to need antennas to be attached to both of the Radios used in this example.

For more information on how to solder an antenna to the RFM95, please click here

Committer:
dev_alexander
Date:
Fri Jun 01 22:07:08 2018 +0000
Revision:
19:9f035b9e65ec
Parent:
18:d5527ce82e6b
got this sample program for 2+ sx1276 modules to communicate in a ping pong fashion. This program has been tested and verified to run with 915MHz Hope RFM95 modules running with MAX32620FTHR and MAX32630FTHR micro controllers.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Helmut64 0:c43b6919ae15 1 /*
Helmut64 17:98f2528e8399 2 * Copyright (c) 2018 HELIOS Software GmbH
Helmut64 0:c43b6919ae15 3 * 30826 Garbsen (Hannover) Germany
Helmut64 0:c43b6919ae15 4 * Licensed under the Apache License, Version 2.0);
Helmut64 0:c43b6919ae15 5 */
Helmut64 0:c43b6919ae15 6 #include "main.h"
Helmut64 0:c43b6919ae15 7
dev_alexander 19:9f035b9e65ec 8 #if defined(TARGET_MAX32630FTHR) // using the RFM95 board
dev_alexander 19:9f035b9e65ec 9 #include "max32630fthr.h"
dev_alexander 19:9f035b9e65ec 10 MAX32630FTHR pegasus(MAX32630FTHR::VIO_3V3);
dev_alexander 19:9f035b9e65ec 11 #endif
Helmut64 0:c43b6919ae15 12
Helmut64 17:98f2528e8399 13 DigitalOut myled(LED);
Helmut64 0:c43b6919ae15 14
Helmut64 0:c43b6919ae15 15
Helmut64 17:98f2528e8399 16 int main() {
Helmut64 17:98f2528e8399 17 #ifdef HELTEC_STM32L4
Helmut64 17:98f2528e8399 18 DigitalOut vext(POWER_VEXT);
Helmut64 17:98f2528e8399 19 vext = POWER_VEXT_ON;
Helmut64 17:98f2528e8399 20 #endif
dev_alexander 19:9f035b9e65ec 21
dev_alexander 19:9f035b9e65ec 22
Helmut64 17:98f2528e8399 23 /*
Helmut64 17:98f2528e8399 24 * inits the Serial or USBSerial when available (230400 baud).
Helmut64 17:98f2528e8399 25 * If the serial uart is not is not connected it swiches to USB Serial
Helmut64 17:98f2528e8399 26 * blinking LED means USBSerial detected, waiting for a connect.
Helmut64 17:98f2528e8399 27 * It waits up to 30 seconds for a USB terminal connections
Helmut64 17:98f2528e8399 28 */
Helmut64 17:98f2528e8399 29 InitSerial(30*1000, &myled);
Helmut64 17:98f2528e8399 30 dprintf("Welcome to the SX1276GenericLib");
Helmut64 18:d5527ce82e6b 31
Helmut64 17:98f2528e8399 32 dprintf("Starting a simple LoRa PingPong");
Helmut64 17:98f2528e8399 33 SX1276PingPong();
Helmut64 0:c43b6919ae15 34 }