I'm trying to implement a program for this sensor that measures NH3, NO2 and CO, but seems like there are no libraries . It has 3 analog channels and i've tried to implement a program to transform the analog values into ppm, but with no result ( i got 900 ppm for CO, which is impossible, for examples). The code that i tried to use is: void setup() { Serial.begin(9600); delay(1000); Serial.println("Setup initializing"); pinMode(A0, INPUT); pinMode(A1, INPUT); pinMode(A2, INPUT); } void loop() { int a0_read = analogRead(A0); int co = map(a0_read,0, 1023, 0, 1000 ); int a1_read = analogRead(A1); int nh3 = map(a1_read, 0, 1023, 0, 500); //NH3 int a2_read = analogRead(A2); int no2 = map(a2_read, 0, 1023, 0.05, 10 ); //NH3 Serial.print("CO:"); Serial.print(a0_read); Serial.println(" ppm"); Serial.print("NH3:"); Serial.print(a1_read); Serial.println(" ppm"); Serial.print("NO2:"); Serial.print(a2_read); Serial.println(" ppm"); delay(10000); } The schematic: [image] Each blue line goes to A0, A1 and A2 on my arduino. The analogic ports are pulled up to the +5V using 3 47k resistors. I saw the firmware of the i2c variant and i saw this piece of code: int A0_0 = get_addr_dta(6, ADDR_USER_ADC_HN3); int A0_1 = get_addr_dta(6, ADDR_USER_ADC_CO); int A0_2 = get_addr_dta(6, ADDR_USER_ADC_NO2); int An_0 = get_addr_dta(CH_VALUE_NH3); int An_1 = get_addr_dta(CH_VALUE_CO); int An_2 = get_addr_dta(CH_VALUE_NO2); ratio0 = (float)An_0 / (float)A0_0 * (1023.0 - A0_0) / (1023.0 - An_0); ratio1 = (float)An_1 / (float)A0_1 * (1023.0 - A0_1) / (1023.0 - An_1); ratio2 = (float)An_2 / (float)A0_2 * (1023.0 - A0_2) / (1023.0 - An_2); } float c = 0; switch (gas) { case CO: { c = pow(ratio1, -1.179) * 4.385; //mod by jack break; } case NO2: { c = pow(ratio2, 1.007) / 6.855; //mod by jack break; } case NH3: { c = pow(ratio0, -1.67) / 1.47; //modi by jack break; } But i have no idea how to implement on my analog version since i don t know how to get int A0_0 = get_addr_dta(6, ADDR_USER_ADC_HN3); int A0_1 = get_addr_dta(6, ADDR_USER_ADC_CO); int A0_2 = get_addr_dta(6, ADDR_USER_ADC_NO2); int An_0 = get_addr_dta(CH_VALUE_NH3); int An_1 = get_addr_dta(CH_VALUE_CO); int An_2 = get_addr_dta(CH_VALUE_NO2);

Are you tying to search the forum and google? [image] MiCS-6814 / CJMCU-6814 gas sensor reading conversion Sensors Hello, I'm using this gas sensor to measure CO, NO2, and NH3 for my university project. I used these as reference to program the sensor: And this is my results: [image] The reading I received was in volts, so I'm wondering how to convert the reading to ppm or ug/m3? (the datasheet does not specify the conversion) Datasheet: https://www.sgxsensortech.com/content/uploads/2015/02/1143_Datasheet-MiCS-6814-rev-8.pdf Code: #include dht DHT; #define DHT11_PIN 7 const float max_volts… [image] CJMCU-6814 adapter board with MICS-6814 CO/NH3/NO2-sensor Sensors Hi folks! I'm working with air quality monitor and using this quite easily available module/adapter: https://www.aliexpress.com/item/CJMCU-MICS-6814-Air-Quality-CO-VOC-NH3-Nitrogen-Oxygen-Gas-Sensor/32762216430.html It's main and only sensor component is MICS-6814: https://www.mouser.fi/datasheet/2/18/1143_Datasheet-MiCS-6814-rev-8-1144828.pdf Using clone Mega2560 and reading values through serial monitor. Using old ATX-PSU as a power supply, stripped one IDE-power connector to get +12V, +5V …

Done it and haven't found what I need. I got weird values, even tho I burned the sensor for 48 hours and using the map function.

Have you got convertion to ppm method? i wonder if i can use other Ro value instead. Also, i am confused how to interpret this program lines to mathematical equation or where it is come from: example is CO: c = pow(ratio1, -1.179) * 4.385;

enum channel { CH_NH3, CH_RED, CH_OX }; typedef enum channel channel_t; // Enum for proper gas declaration enum gas { CO, NO2, NH3, C3H8, C4H10, CH4, H2, C2H5OH }; typedef enum gas gas_t; #define NH3PIN A1 #define COPIN A0 #define OXPIN A2 uint16_t NH3baseR; uint16_t REDbaseR; uint16_t OXbaseR; /** Requests the current resistance for a given channel from the sensor. The value is an ADC value between 0 and 1024. @param channel The channel to read the base resistance from. @return The unsigned 16-bit base resistance of the selected channel. */ uint16_t getResistance(channel_t channel) { unsigned long rs = 0; int counter = 0; switch (channel) { case CH_NH3: for(int i = 0; i < 100; i++) { rs += analogRead(NH3PIN); counter++; delay(2); } return rs/counter; case CH_RED: for(int i = 0; i < 100; i++) { rs += analogRead(COPIN); counter++; delay(2); } return rs/counter; case CH_OX: for(int i = 0; i < 100; i++) { rs += analogRead(OXPIN); counter++; delay(2); } return rs/counter; } return 0; } void calibrateMICS() { // Continuously measure the resistance, // storing the last N measurements in a circular buffer. // Calculate the floating average of the last seconds. // If the current measurement is close to the average stop. // Seconds to keep stable for successful calibration // (Keeps smaller than 64 to prevent overflows) uint8_t seconds = 10; // Allowed delta for the average from the current value uint8_t delta = 2; // Circular buffer for the measurements uint16_t bufferNH3[seconds]; uint16_t bufferRED[seconds]; uint16_t bufferOX[seconds]; // Pointers for the next element in the buffer uint8_t pntrNH3 = 0; uint8_t pntrRED = 0; uint8_t pntrOX = 0; // Current floating sum in the buffer uint16_t fltSumNH3 = 0; uint16_t fltSumRED = 0; uint16_t fltSumOX = 0; // Current measurements; uint16_t curNH3; uint16_t curRED; uint16_t curOX; // Flag to see if the channels are stable bool NH3stable = false; bool REDstable = false; bool OXstable = false; // Initialize buffer for (int i = 0; i < seconds; ++i) { bufferNH3[i] = 0; bufferRED[i] = 0; bufferOX[i] = 0; } do { // Wait a second delay(1000); Serial.print("."); // Read new resistances unsigned long rs = 0; delay(50); for (int i = 0; i < 3; i++) { delay(1); rs += analogRead(NH3PIN); } curNH3 = rs/3; rs = 0; delay(50); for (int i = 0; i < 3; i++) { delay(1); rs += analogRead(COPIN); } curRED = rs/3; rs = 0; delay(50); for (int i = 0; i < 3; i++) { delay(1); rs += analogRead(OXPIN); } curOX = rs/3; // Update floating sum by subtracting value // about to be overwritten and adding the new value. fltSumNH3 = fltSumNH3 + curNH3 - bufferNH3[pntrNH3]; fltSumRED = fltSumRED + curRED - bufferRED[pntrRED]; fltSumOX = fltSumOX + curOX - bufferOX[pntrOX]; // Store new measurement in buffer bufferNH3[pntrNH3] = curNH3; bufferRED[pntrRED] = curRED; bufferOX[pntrOX] = curOX; // Determine new state of flags NH3stable = abs(fltSumNH3 / seconds - curNH3) < delta; REDstable = abs(fltSumRED / seconds - curRED) < delta; OXstable = abs(fltSumOX / seconds - curOX) < delta; // Advance buffer pointer pntrNH3 = (pntrNH3 + 1) % seconds ; pntrRED = (pntrRED + 1) % seconds; pntrOX = (pntrOX + 1) % seconds; //Mikä kestää? if(!NH3stable) { Serial.print("(NH3:"); Serial.print(abs(fltSumNH3 / seconds - curNH3)); Serial.println(")"); } if(!REDstable) { Serial.print("(RED:"); Serial.print(abs(fltSumRED / seconds - curRED)); Serial.println(")"); } if(!OXstable) { Serial.print("(OX:"); Serial.print(abs(fltSumOX / seconds - curOX)); Serial.println(")"); } } while (!NH3stable || !REDstable || !OXstable); NH3baseR = fltSumNH3 / seconds; REDbaseR = fltSumRED / seconds; OXbaseR = fltSumOX / seconds; // Store new base resistance values in EEPROM } uint16_t getBaseResistance(channel_t channel) { /* if (1 == __version) { // Version 1 can query every channel independently // Reply is 4 bytes long with relevant data in second and third byte switch (channel) { case CH_NH3: return getRuntimeData(CMD_V1_GET_R0_NH3, 4, 1); case CH_RED: return getRuntimeData(CMD_V1_GET_R0_RED, 4, 1); case CH_OX: return getRuntimeData(CMD_V1_GET_R0_OX, 4, 1); } } if (2 == __version) { // Version 2 uses the same command every time, but different offsets*/ switch (channel) { case CH_NH3: return NH3baseR; case CH_RED: return REDbaseR; case CH_OX: return OXbaseR; } // } return 0; } /** Calculates the current resistance ratio for the given channel. @param channel The channel to request resistance values from. @return The floating-point resistance ratio for the given channel. */ float getCurrentRatio(channel_t channel) { float baseResistance = (float) getBaseResistance(channel); float resistance = (float) getResistance(channel); return resistance / baseResistance * (1023.0 - baseResistance) / (1023.0 - resistance); return -1.0; } /** Measures the gas concentration in ppm for the specified gas. @param gas The gas to calculate the concentration for. @return The current concentration of the gas in parts per million (ppm). */ float measureMICS(gas_t gas) { float ratio; float c = 0; switch (gas) { case CO: ratio = getCurrentRatio(CH_RED); c = pow(ratio, -1.179) * 4.385; break; case NO2: ratio = getCurrentRatio(CH_OX); c = pow(ratio, 1.007) / 6.855; break; case NH3: ratio = getCurrentRatio(CH_NH3); c = pow(ratio, -1.67) / 1.47; break; case C3H8: ratio = getCurrentRatio(CH_NH3); c = pow(ratio, -2.518) * 570.164; break; case C4H10: ratio = getCurrentRatio(CH_NH3); c = pow(ratio, -2.138) * 398.107; break; case CH4: ratio = getCurrentRatio(CH_RED); c = pow(ratio, -4.363) * 630.957; break; case H2: ratio = getCurrentRatio(CH_RED); c = pow(ratio, -1.8) * 0.73; break; case C2H5OH: ratio = getCurrentRatio(CH_RED); c = pow(ratio, -1.552) * 1.622; break; } return isnan(c) ? -1 : c; } example of values : nh3 = 0.7 ppm, co = 4.6 ppm and no2 = 0.17 ppm. I guess its ok based on the limits speculated on internet.

CJMCU-6814 readings into ppm

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b707 May 8, 2024, 6:44pm 2

Are you tying to search the forum and google?

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CJMCU-6814 readings into ppm

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