Hello, I’m trying to get the RAK 12047 VOC Gas Sensor module to function. However I’m getting “Data too long to fit in transmit buffer” errors from the Sensirion SGP40 / Arduino Wire library and have run out of ideas on what could cause this.
We use the 2nd generation RAK19007 base board with the RAK 11200 ESP32 core. The only other module connected is the RAK12047 Gas Sensor, which is connected to Slot A. I have confirmed that my development environment using the Arduino IDE functions correctly and have also tried the RAK18001 Buzzer module (now temporarily disconnected) before successfully. So I’m quite confident the problem shouldn’t be in the compilation of flashing stages.
For the RAK12047 I’m just trying to get the example from the official Quick Start Guide working. I have only modified the WB_IO variable to refer to slot A. Just to confirm, below is the exact .ino file I use:
/**
@file RAK12047_SGP40_GetVOCIndex.ino
@author rakwireless.com
@brief Get the VOC index data from the sensor SGP40 and print it out through the serial port.
The voc index can directly indicate the quality of the air. The higher the value, the worse the air quality.
@version 0.1
@date 2022-1-22
@copyright Copyright (c) 2020
**/
#include <SensirionI2CSgp40.h> // Click here to get the library: http://librarymanager/All#SensirionI2CSgp40
#include <Wire.h>
SensirionI2CSgp40 sgp40;
void setup()
{
uint16_t error;
char errorMessage[256];
uint16_t serialNumber[13];
uint8_t serialNumberSize = 3;
pinMode(WB_IO1, OUTPUT);
digitalWrite(WB_IO1, HIGH);
// Initialize Serial for debug output
time_t timeout = millis();
Serial.begin(115200);
while (!Serial)
{
if ((millis() - timeout) < 5000)
{
delay(100);
}
else
{
break;
}
}
Serial.println("RAK12047 SGP40 example");
Wire.begin();
sgp40.begin(Wire);
error = sgp40.getSerialNumber(serialNumber, serialNumberSize);
if (error)
{
Serial.print("Error trying to execute getSerialNumber(): ");
errorToString(error, errorMessage, 256);
Serial.println(errorMessage);
}
else
{
Serial.print("Serial Number:");
Serial.print("0x");
for (size_t i = 0; i < serialNumberSize; i++)
{
uint16_t value = serialNumber[i];
Serial.print(value < 4096 ? "0" : "");
Serial.print(value < 256 ? "0" : "");
Serial.print(value < 16 ? "0" : "");
Serial.print(value, HEX);
}
Serial.println();
}
uint16_t testResult;
error = sgp40.executeSelfTest(testResult);
if (error)
{
Serial.print("Error trying to execute executeSelfTest(): ");
errorToString(error, errorMessage, 256);
Serial.println(errorMessage);
}
else if (testResult != 0xD400)
{
Serial.print("executeSelfTest failed with error: ");
Serial.println(testResult);
}
}
void loop()
{
uint16_t error;
char errorMessage[256];
uint16_t srawVoc = 0;
float vocIndex = 0;
/*
* @brief Set the relative humidity and temperature in the current environment.
* Temperature and humidity calibration has been performed inside the sensor.
* RH/ticks=RH/%×65535/100
* T/ticks=(T/°C + 45)×65535/175
*/
uint16_t defaultRh = 0x8000; // 50 %RH
uint16_t defaultT = 0x6666; // 25 ℃
delay(1000);
error = sgp40.measureRawSignal(defaultRh, defaultT, srawVoc);
if (error)
{
Serial.print("Error trying to execute measureRawSignal(): ");
errorToString(error, errorMessage, 256);
Serial.println(errorMessage);
}
else
{
Serial.print("SRAW_VOC:");
Serial.print(srawVoc);
vocIndex = (float)srawVoc/131.07 ;
/* VOC index.
* The voc index can directly indicate the quality of the air. The higher the value, the worse the air quality.
* 0-100，no need to ventilate,purify.
* 100-200，no need to ventilate,purify.
* 200-400，ventilate,purify.
* 400-500，ventilate,purify intensely.
*/
Serial.print(" VOC Index:");
Serial.println(vocIndex);
}
}
But when I run the code I only get the following output:
-> RAK12047 SGP40 example
-> Error trying to execute getSerialNumber(): Data too long to fit in transmit buffer
-> Error trying to execute executeSelfTest(): Data too long to fit in transmit buffer
-> Error trying to execute measureRawSignal(): Data too long to fit in transmit buffer
-> Error trying to execute measureRawSignal(): Data too long to fit in transmit buffer
-> Error trying to execute measureRawSignal(): Data too long to fit in transmit buffer
...
Could someone help tell me what am I doing wrong here?
