Connecting LED lights to sensor readings

Other Hardware LEDs and Multiplexing
1

I'm displaying the readings from a pm2.5 particle sensor from Plantower onto an oled display, and also displaying the calculated AQI from that data onto the same oled display. I'm using an Arduino R4 Uno Wifi for this. Is it possible to connect different LED lights to correspond with the AQI reading? (ex. 0-12 lights up a green LED, 12-40 is yellow, 40-55 is red, 150+ is black). I've tried a couple different ways, but none of them seem to work.

Here's the code for displaying the readings and calculating the AQI:

#include <SoftwareSerial.h>
SoftwareSerial pmsSerial(2, 3);


#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>


#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);


#define LOGO16_GLCD_HEIGHT 64
#define LOGO16_GLCD_WIDTH 128


#if (SSD1306_LCDHEIGHT != 32)
#error("Height incorrect, please fix Adafruit_SSD1306.h!");
#endif


void setup() {
 delay(3000);
 display.begin(SSD1306_SWITCHCAPVCC, 0x3C); display.display();
 delay(2000);
 display.clearDisplay();


 pmsSerial.begin(9600);
}


struct pms5003data {
 uint16_t framelen;
 uint16_t pm10_standard, pm25_standard, pm100_standard;
 uint16_t pm10_env, pm25_env, pm100_env;
 uint16_t particles_03um, particles_05um, particles_10um, particles_25um, particles_50um, particles_100um;
 uint16_t unused;
 uint16_t checksum;
};


struct pms5003data data;


void loop() {
 if (readPMSdata(&pmsSerial)) {
   String vString5 = String(data.pm25_env);
   String vString6 = String(data.pm100_env);


   display.clearDisplay();


   showText("PM2.5:", 1, 14, 1, false);
   showText(vString5 + " ug/M^2", 50, 14, 1, false);


   showText("PM10 :", 1, 24, 1, false);
   showText(vString6 + " ug/M^2", 50, 24, 1, false);


   int aqival = calcAQI25(data.pm25_env);
   showText("AQI:" + String(aqival), 1, 1, 1, false);
   String aqi_text = make_aqi_words(aqival);
   showText(aqi_text, 50, 1, 1, false);


   display.display();


   delay(1000);
}
}


boolean readPMSdata(Stream *s) {
 if (!s->available()) {
   return false;
 }


 if (s->peek() != 0x42) {
   s->read();
   return false;
 }


 if (s->available() < 32) {
   return false;
 }


 uint8_t buffer[32];
 uint16_t sum = 0;
 s->readBytes(buffer, 32);


 for (uint8_t i = 0; i < 30; i++) {
   sum += buffer[i];
 }


 uint16_t buffer_u16[15];
 for (uint8_t i = 0; i < 15; i++) {
   buffer_u16[i] = buffer[2 + i * 2 + 1];
   buffer_u16[i] += (buffer[2 + i * 2] << 8);
 }


 memcpy((void *)&data, (void *)buffer_u16, 30);


 if (sum != data.checksum) {
   Serial.println("Checksum failure");
   return false;
 }
 return true;
}


void showText(String text, int x, int y, int size, boolean d) {
 display.setTextSize(size);
 display.setTextColor(WHITE);
 display.setCursor(x, y);
 display.println(text);
 if (d) {
   display.display();
 }
}




int calcAQI25(int pm25) {


 // Uses formula AQI = ( (pobs - pmin) x (aqimax - aqimin) ) / (pmax - pmin)  + aqimin
 float pmin, pmax, amin, amax;


 if (pm25 <= 12) {
   pmin = 0;
   pmax = 12;
   amin = 0;
   amax = 50;
   goto aqicalc;
 }
 if (pm25 <= 35.5) {
   pmin = 12;
   pmax = 35.5;
   amin = 50;
   amax = 100;
   goto aqicalc;
 }
 if (pm25 <= 55.5) {
   pmin = 35.5;
   pmax = 55.5;
   amin = 100;
   amax = 150;
   goto aqicalc;
 }
 if (pm25 <= 150.5) {
   pmin = 55.5;
   pmax = 150.5;
   amin = 150;
   amax = 200;
   goto aqicalc;
 }
 if (pm25 <= 250.5) {
   pmin = 150.5;
   pmax = 250.5;
   amin = 200;
   amax = 300;
   goto aqicalc;
 }
 if (pm25 <= 350.5) {
   pmin = 250.5;
   pmax = 350.5;
   amin = 300;
   amax = 400;
   goto aqicalc;
 }
 if (pm25 <= 500.5) {
   pmin = 350.5;
   pmax = 500.5;
   amin = 400;
   amax = 500;
   goto aqicalc;
 } else {
   return 999;
 }


aqicalc:
 float aqi = (((pm25 - pmin) * (amax - amin)) / (pmax - pmin)) + amin;
 return aqi;
}


String make_aqi_words(float aqival) {
 if (aqival <= 12) { return "Good"; }
 if (aqival <= 35.5) { return "Medium"; }
 if (aqival <= 55.5) { return "Bad"; }
 if (aqival <= 150.5) { return "Very Bad"; }
 if (aqival <= 350.5) { return "Deadly"; }
 return "Error";
}
2

Yes

What's the point of posting code that works? That doesn't need fixing. Post the code you tried that didn't work, and explain what you wanted it to do, and what it actually did.

3

Sounds like an application of the if statement and the && logic operator.

if (aqival >= 12 && aqival <= 40 ) {....}
4

Does a "goto" push the function address on the stack for a "return" to use, or does the "return" go back to the main "loop()"?

5

Yes! You need to test the values and then determine which LED is to be illuminated.

6

Hi arduinofaqn2
This seems to me typical an application that needs switch....case instructions
ciao, Photoncatcher