Here’s an example, similar to the one in my serial tutorial, for sending multiple values from the Arduino to the Photon. It uses snprintf on the Arduino side to print the numbers as text and sscanf on the Photon side to reverse the process.
Arduino code
// Arduino code
// Constants
// Structures
typedef struct {
int temperature;
int humidity;
int pressure;
int luminosity;
int winddir;
int windspeed;
int rainfall;
} WeatherData;
// Forward declarations
void getWeatherData(WeatherData &data);
void sendWeatherData(const WeatherData &data);
// Global variables
char sendBuf[256];
void setup() {
// Serial TX (1) is connected to Photon RX
// Serial RX (0) is connected to Photon TX
// Ardiuno GND is connected to Photon GND
Serial.begin(19200);
}
void loop() {
WeatherData data;
getWeatherData(data);
sendWeatherData(data);
delay(5000);
}
void getWeatherData(WeatherData &data) {
// This just generates random data for testing
data.temperature = rand();
data.humidity = rand();
data.pressure = rand();
data.luminosity = rand();
data.winddir = rand();
data.windspeed = rand();
data.rainfall = rand();
}
void sendWeatherData(const WeatherData &data) {
snprintf(sendBuf, sizeof(sendBuf), "%d,%d,%d,%d,%d,%d,%d\n",
data.temperature, data.humidity, data.pressure, data.luminosity, data.winddir, data.windspeed, data.rainfall);
Serial.print(sendBuf);
}
Photon code
#include "Particle.h"
// Constants
const size_t READ_BUF_SIZE = 256;
// Structures
typedef struct {
int temperature;
int humidity;
int pressure;
int luminosity;
int winddir;
int windspeed;
int rainfall;
} WeatherData;
// Forward declarations
void processBuffer();
void handleWeatherData(const WeatherData &data);
// Global variables
int counter = 0;
unsigned long lastSend = 0;
char readBuf[READ_BUF_SIZE];
size_t readBufOffset = 0;
void setup() {
Serial.begin(9600);
// Serial1 RX is connected to Arduino TX (1)
// Serial2 TX is connected to Arduino RX (0)
// Photon GND is connected to Arduino GND
Serial1.begin(19200);
}
void loop() {
// Read data from serial
while(Serial1.available()) {
if (readBufOffset < READ_BUF_SIZE) {
char c = Serial1.read();
if (c != '\n') {
// Add character to buffer
readBuf[readBufOffset++] = c;
}
else {
// End of line character found, process line
readBuf[readBufOffset] = 0;
processBuffer();
readBufOffset = 0;
}
}
else {
Serial.println("readBuf overflow, emptying buffer");
readBufOffset = 0;
}
}
}
void processBuffer() {
// Serial.printlnf("Received from Arduino: %s", readBuf);
WeatherData data;
if (sscanf(readBuf, "%d,%d,%d,%d,%d,%d,%d", &data.temperature, &data.humidity, &data.pressure,
&data.luminosity, &data.winddir, &data.windspeed, &data.rainfall) == 7) {
handleWeatherData(data);
}
else {
Serial.printlnf("invalid data %s", readBuf);
}
}
void handleWeatherData(const WeatherData &data) {
Serial.printlnf("got temperature=%d humidity=%d pressure=%d luminosity=%d winddir=%d windspeed=%d rainfall=%d",
data.temperature, data.humidity, data.pressure, data.luminosity, data.winddir, data.windspeed, data.rainfall);
}
