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Support for setting ENVDATA using temperature in C and humidity as percent #13

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Support for setting ENVDATA using temperature in C and humidity as percent #13

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Support for setting ENVDATA using temperature in C and humidity as pe…
eried Feb 6, 2019
96e3c73
Type mistake
eried Feb 6, 2019
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1 change: 1 addition & 0 deletions keywords.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@ application_version KEYWORD2

geterror_id KEYWORD2
set_envdata KEYWORD2
set_envdataDHT KEYWORD2
set_envdata210 KEYWORD2
get_baseline KEYWORD2
set_baseline KEYWORD2
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48 changes: 48 additions & 0 deletions src/ccs811.cpp
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
/*
ccs811.cpp - Library for the CCS811 digital gas sensor for monitoring indoor air quality from ams.
2019 feb 02 v11 Erwin Ried Added envdata with C and % as parameters
2019 jan 22 v10 Maarten Pennings Added F() on all strings, added get/set_baseline()
2019 jan 15 v9 Maarten Pennings Function set_envdata did not write T; flash now uses PROGMEM array; flash now works without app, better PRINT macros, removed warnings
2018 dec 06 v8 Maarten Pennings Added firmware flash routine
Expand Down Expand Up @@ -320,6 +321,53 @@ bool CCS811::set_envdata(uint16_t t, uint16_t h) {
return ok;
}

// Writes temperature and relativeHumidity (with temperature in C and humidity as percent) to ENV_DATA . Returns false on I2C problems.
bool CCS811::set_envdataDHT(float temperature, float relativeHumidity) {
// Based on: https://github.com/sparkfun/SparkFun_CCS811_Arduino_Library/blob/master/src/SparkFunCCS811.cpp
//Check for invalid temperatures
temperature = max(-25,min(temperature,50));

//Check for invalid humidity
relativeHumidity = max(0,min(relativeHumidity,100));
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Unfortunately, this was not compiling on my side. Maybe I had wired settings in the compiler. But changing that to the following code worked for me:

Suggested change
//Check for invalid temperatures
temperature = max(-25,min(temperature,50));
//Check for invalid humidity
relativeHumidity = max(0,min(relativeHumidity,100));
//Check for invalid temperatures
temperature = max(-25.0f,min(temperature,50.0f));
//Check for invalid humidity
relativeHumidity = max(0.0f,min(relativeHumidity,100.0f));


uint32_t rH = relativeHumidity * 1000; //42.348 becomes 42348
uint32_t temp = temperature * 1000; //23.2 becomes 23200

byte envdata[4];

//Split value into 7-bit integer and 9-bit fractional

//Incorrect way from datasheet.
//envData[0] = ((rH % 1000) / 100) > 7 ? (rH / 1000 + 1) << 1 : (rH / 1000) << 1;
//envData[1] = 0; //CCS811 only supports increments of 0.5 so bits 7-0 will always be zero
//if (((rH % 1000) / 100) > 2 && (((rH % 1000) / 100) < 8))
//{
// envData[0] |= 1; //Set 9th bit of fractional to indicate 0.5%
//}

//Correct rounding. See issue 8: https://github.com/sparkfun/Qwiic_BME280_CCS811_Combo/issues/8
envdata[0] = (rH + 250) / 500;
envdata[1] = 0; //CCS811 only supports increments of 0.5 so bits 7-0 will always be zero

temp += 25000; //Add the 25C offset
//Split value into 7-bit integer and 9-bit fractional
//envData[2] = ((temp % 1000) / 100) > 7 ? (temp / 1000 + 1) << 1 : (temp / 1000) << 1;
//envData[3] = 0;
//if (((temp % 1000) / 100) > 2 && (((temp % 1000) / 100) < 8))
//{
// envData[2] |= 1; //Set 9th bit of fractional to indicate 0.5C
//}

//Correct rounding
envdata[2] = (temp + 250) / 500;
envdata[3] = 0;

wake_up();
// Serial.print(" [T="); Serial.print(t); Serial.print(" H="); Serial.print(h); Serial.println("] ");
bool ok = i2cwrite(CCS811_ENV_DATA,4,envdata);
wake_down();
return ok;
}

// Writes t and h (in ENS210 format) to ENV_DATA. Returns false on I2C problems.
bool CCS811::set_envdata210(uint16_t t, uint16_t h) {
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2 changes: 2 additions & 0 deletions src/ccs811.h
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
/*
ccs811.h - Library for the CCS811 digital gas sensor for monitoring indoor air quality from ams.
2019 feb 02 v11 Erwin Ried Added envdata with C and % as parameters
2019 jan 22 v10 Maarten Pennings Added F() on all strings, added get/set_baseline()
2019 jan 15 v9 Maarten Pennings Flash&i2cwrite now use const array
2018 dec 06 v8 Maarten Pennings Added firmware flash routine
Expand Down Expand Up @@ -75,6 +76,7 @@ class CCS811 {
int application_version(void); // Gets version of the CCS811 application (returns -1 on I2C failure)
int get_errorid(void); // Gets the ERROR_ID [same as 'err' part of 'errstat' in 'read'] (returns -1 on I2C failure)
bool set_envdata(uint16_t t, uint16_t h); // Writes t and h to ENV_DATA (see datasheet for format). Returns false on I2C problems.
bool set_envdataDHT(float temperature, float relativeHumidity); // Writes temperature and relativeHumidity (with temperature in C and humidity as percent) to ENV_DATA . Returns false on I2C problems.
bool set_envdata210(uint16_t t, uint16_t h); // Writes t and h (in ENS210 format) to ENV_DATA. Returns false on I2C problems.
bool get_baseline(uint16_t *baseline); // Reads (encoded) baseline from BASELINE. Returns false on I2C problems. Get it, just before power down (but only when sensor was on at least 20min) - see CCS811_AN000370
bool set_baseline(uint16_t baseline); // Writes (encoded) baseline to BASELINE. Returns false on I2C problems. Set it, after power up (and after 20min)
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