How to determine the model number

[learning88]

hello everyone, Can you tell SCD41 or SCD40 by the serial number?

[qfisch]

Hello @learning88 ,

As far as I know there is no public mapping between serial and model. A simple solution to distinguish them is to request a single shot measurement as it will only work on SCD41. SCD40 would return an error.

Hope that helps you Q

edit: This solution is not valid since SCD40 will technically also answer a single shot measurement request.

[learning88]

@qfisch

Ok, thank you

[learning88]

I used measureSingleShot,scd40 did not return an error @qfisch

[qfisch]

Hello @learning88 Are you using a Sensirion SCD4x development board ?

[learning88]

hi @qfisch no,I using arduino Pro. Is there any other difference? I tried looking at the current. Doesn't seem to make a difference

[qfisch]

Can you link me to this SCD4x module you are using ?

[learning88]

I bought the chip directly and soldered it onto the pcb I drew. /*

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• this list of conditions and the following disclaimer in the documentation
• and/or other materials provided with the distribution.
• • Neither the name of Sensirion AG nor the names of its
• contributors may be used to endorse or promote products derived from
• this software without specific prior written permission.
• THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
• AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
• IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
• ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
• LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
• CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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• CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
• ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
• POSSIBILITY OF SUCH DAMAGE. */

include

include

include

SensirionI2CScd4x scd4x;

void printUint16Hex(uint16_t value) { Serial.print(value < 4096 ? "0" : ""); Serial.print(value < 256 ? "0" : ""); Serial.print(value < 16 ? "0" : ""); Serial.print(value, HEX); }

void printSerialNumber(uint16_t serial0, uint16_t serial1, uint16_t serial2) { Serial.print("Serial: 0x"); printUint16Hex(serial0); printUint16Hex(serial1); printUint16Hex(serial2); Serial.println(); }

void setup() {

Serial.begin(115200);
while (!Serial) {
    delay(100);
}

Wire.begin();

uint16_t error;
char errorMessage[256];

scd4x.begin(Wire);

// stop potentially previously started measurement
error = scd4x.stopPeriodicMeasurement();
if (error) {
    Serial.print("Error trying to execute stopPeriodicMeasurement(): ");
    errorToString(error, errorMessage, 256);
    Serial.println(errorMessage);
}

uint16_t serial0;
uint16_t serial1;
uint16_t serial2;
error = scd4x.getSerialNumber(serial0, serial1, serial2);
if (error) {
    Serial.print("Error trying to execute getSerialNumber(): ");
    errorToString(error, errorMessage, 256);
    Serial.println(errorMessage);
} else {
    printSerialNumber(serial0, serial1, serial2);
}

// Start Measurement

// error = scd4x.startPeriodicMeasurement(); // if (error) { // Serial.print("Error trying to execute startPeriodicMeasurement(): "); // errorToString(error, errorMessage, 256); // Serial.println(errorMessage); // }

Serial.println("Waiting for first measurement... (5 sec)");

}

void loop() { uint16_t error; char errorMessage[256]; error=scd4x.measureSingleShot(); if (error) { Serial.print("Error trying to execute startPeriodicMeasurement(): "); errorToString(error, errorMessage, 256); Serial.println(errorMessage); } delay(5000);

// Read Measurement
uint16_t co2;
float temperature;
float humidity;
error = scd4x.readMeasurement(co2, temperature, humidity);
if (error) {
    Serial.print("Error trying to execute readMeasurement(): ");
    errorToString(error, errorMessage, 256);
    Serial.println(errorMessage);
} else if (co2 == 0) {
    Serial.println("Invalid sample detected, skipping.");
} else {
    Serial.print("Co2:");
    Serial.print(co2);
    Serial.print("\t");
    Serial.print("Temperature:");
    Serial.print(temperature);
    Serial.print("\t");
    Serial.print("Humidity:");
    Serial.println(humidity);
}

}

[learning88]

output: Serial: 0x39920F073B11 Waiting for first measurement... (5 sec) Co2:993 Temperature:16.45 Humidity:64.15 Co2:990 Temperature:16.81 Humidity:63.20 Co2:984 Temperature:17.09 Humidity:61.85 Co2:935 Temperature:17.28 Humidity:60.87 Co2:899 Temperature:17.42 Humidity:60.17 Co2:896 Temperature:17.54 Humidity:59.70

[learning88]

Here's another one: Serial: 0x46E017073BA7 Waiting for first measurement... (5 sec) Co2:1445 Temperature:17.47 Humidity:62.29 Co2:1422 Temperature:17.82 Humidity:61.16 Co2:1365 Temperature:18.01 Humidity:60.37 Co2:1345 Temperature:18.20 Humidity:59.67

[learning88]

The yellow one is scd41, right?

[qfisch]

There is no way to know from the measurements unfortunately. I am looking internally if there is an identification method that I would not be aware of (it does not look good so far). We are aware of this issue with SCD4x sensors. Sensors will be engraved in the future to avoid this situation. I will for sure come back to you if I find a solution.

[learning88]

@qfisch

Ok, thank you.