sigmasternchen/MH-Z-CO2-Sensors
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Also defined CO2_IN and more logging.

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This commit is contained in:
Tobias Schürg 2018-06-23 12:35:27 +02:00
parent cd9a51f5a4
commit 4daa920efd
1 changed files with 14 additions and 5 deletions
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19
MH-Z19B.ino
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@ -1,25 +1,32 @@
#define CO2_IN D2
#define MH_Z19_RX D7
#define MH_Z19_TX D6
#include <SoftwareSerial.h>
SoftwareSerial co2Serial(7, 6); // define MH-Z19 RX TX
SoftwareSerial co2Serial(MH_Z19_RX, MH_Z19_TX); // define MH-Z19 RX TX
unsigned long startTime = millis();
void setup() {
Serial.begin(9600);
co2Serial.begin(9600);
pinMode(9, INPUT);
pinMode(CO2_IN, INPUT);
}
void loop() {
Serial.println("------------------------------");
Serial.print("Time from start: ");
Serial.print((millis() - startTime) / 1000);
Serial.println(" s");
int ppm_uart = readCO2UART();
int ppm_pwm = readCO2PWM();
Serial.println("\n------------------------------");
delay(5000);
}
int readCO2UART() {
Serial.println("-- read CO2 uart ---");
byte cmd[9] = {0xFF, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x79};
byte response[9]; // for answer
@ -77,7 +84,8 @@ int readCO2UART() {
return ppm_uart;
}
byte getCheckSum(char *packet) {
byte getCheckSum(byte *packet) {
Serial.println("-- get checksum ---");
byte i;
unsigned char checksum = 0;
for (i = 1; i < 8; i++) {
@ -89,9 +97,10 @@ byte getCheckSum(char *packet) {
}
int readCO2PWM() {
Serial.println("-- read CO2 pwm ---");
unsigned long th, tl, ppm_pwm = 0;
do {
th = pulseIn(9, HIGH, 1004000) / 1000;
th = pulseIn(CO2_IN, HIGH, 1004000) / 1000;
tl = 1004 - th;
ppm_pwm = 5000 * (th - 2) / (th + tl - 4);
} while (th == 0);