arduino stm32 lora master slave sensor device and gateway

stm32-lora-gw.ino

#include <LoRa.h>

#include <Wire.h>
#include <I2CSoilMoistureSensor.h>

#define MAGIC 0x74736574 // "test"
#define BUTTON 1

static volatile bool ready = false;
static I2CSoilMoistureSensor sensor;

enum Mode {
	NONE,
	SLAVE,
	MASTER,
} static volatile mode;

struct Data {
	long magic;
	long identifier; // device id
	long cap;        // 4-byte = 32-bit
	long temp;       // 4-byte = 32-bit
	long reserved[4];
} __attribute__((packed)) static volatile datapkg = {
	.magic = MAGIC,
};

struct Config {
	long magic;
	long identifier;
	long freq;
	long sleep_wait;
	long wake_interval;
	long reserved[4];
} __attribute__((packed)) static volatile configpkg = {
	.magic = MAGIC,
};

void onReceive(int packetSize) {
	if(!packetSize) return;                // invalid packet 0-length
	int rssi = LoRa.packetRssi();
	float snr = LoRa.packetSnr();
	long freqErr = LoRa.packetFrequencyError();
	switch(packetSize) {
		case sizeof(datapkg):
			LoRa.readBytes((uint8_t*) &datapkg, sizeof(datapkg));
			ready = (MAGIC == datapkg.magic);
			break;
		case sizeof(configpkg):
			LoRa.readBytes((uint8_t*) &configpkg, sizeof(configpkg));
			ready = (MAGIC == configpkg.magic);
			break;
		default:
			// invalid packet
			break;
	}
	return;
}

void setup() {
	while(!digitalRead(BUTTON) && millis() < 2222);
	mode = digitalRead(BUTTON) ? MASTER : SLAVE;
	// put your setup code here, to run once:
	Wire.begin();
	LoRa.begin(433E6);
	sensor.begin(true); // reset sensor and wait
	sensor.getCapacitance();
	sensor.getTemperature();
	LoRa.onReceive(onReceive);
	LoRa.receive();
	return;
}

void op_master(void) {
	if(!ready) return;
	/*
	printf("Data: from:%08lx temp:%ld cap:%ld \n",
		datapkg.identifier,
		datapkg.temp,
		datapkg.cap
	);
	*/
	configpkg.freq = 433e6;
	configpkg.identifier = datapkg.identifier;
	configpkg.sleep_wait = 1000;
	configpkg.wake_interval = 60000;
	LoRa.beginPacket();
	LoRa.write((uint8_t*) &configpkg, sizeof(configpkg));
	LoRa.endPacket();
	LoRa.receive();
	return;
}

void op_slave(void) {
	while(sensor.isBusy()) delay(9);
	datapkg.identifier = HAL_GetUIDw0() ^ HAL_GetUIDw1() ^ HAL_GetUIDw2();
	datapkg.cap  = (long)  sensor.getCapacitance();
	datapkg.temp = (long) (sensor.getTemperature() * 10.0);
	LoRa.beginPacket();
	LoRa.write((uint8_t*) &datapkg, sizeof(datapkg));
	LoRa.endPacket();
	LoRa.receive();
	delay(configpkg.sleep_wait);
	return;
}

void loop() {
	switch(mode) {
		case MASTER:
			op_master();
			break;
		case SLAVE:
			op_slave();
			break;
		default:
			// invalid mode
			break;
	}
	return;
}

// https://github.com/Apollon77/I2CSoilMoistureSensor/blob/master/I2CSoilMoistureSensor.cpp#L60
// https://www.empastore.com/stm32-nucleo-32-islemci-kiti-nucleo-l031k6