diff --git a/sonoff/xsns_21_sgp30.ino b/sonoff/xsns_21_sgp30.ino index d8241f1d6..16c4657ad 100644 --- a/sonoff/xsns_21_sgp30.ino +++ b/sonoff/xsns_21_sgp30.ino @@ -34,65 +34,130 @@ Adafruit_SGP30 sgp; uint8_t sgp30_type = 0; uint8_t sgp30_ready = 0; -uint8_t sgp30_counter = 0; +float sgp30_abshum; /********************************************************************************************/ +void sgp30_Init(void) { + if (sgp.begin()) { + sgp30_type = 1; +// snprintf_P(log_data, sizeof(log_data), PSTR("SGP: Serialnumber 0x%04X-0x%04X-0x%04X"), sgp.serialnumber[0], sgp.serialnumber[1], sgp.serialnumber[2]); +// AddLog(LOG_LEVEL_DEBUG); + snprintf_P(log_data, sizeof(log_data), S_LOG_I2C_FOUND_AT, "SGP30", 0x58); + AddLog(LOG_LEVEL_DEBUG); + } +} + +float sgp30_AbsoluteHumidity(float temperature, float humidity,char tempUnit) { + //taken from https://carnotcycle.wordpress.com/2012/08/04/how-to-convert-relative-humidity-to-absolute-humidity/ + //precision is about 0.1°C in range -30 to 35°C + //August-Roche-Magnus 6.1094 exp(17.625 x T)/(T + 243.04) + //Buck (1981) 6.1121 exp(17.502 x T)/(T + 240.97) + //reference https://www.eas.ualberta.ca/jdwilson/EAS372_13/Vomel_CIRES_satvpformulae.html + float temp = NAN; + const float mw = 18.01534; // molar mass of water g/mol + const float r = 8.31447215; // Universal gas constant J/mol/K + + if (isnan(temperature) || isnan(humidity) ) { + return NAN; + } + + if (tempUnit != 'C') { + temperature = (temperature - 32.0) * (5.0 / 9.0); /*conversion to [°C]*/ + } + + temp = pow(2.718281828, (17.67 * temperature) / (temperature + 243.5)); + + //return (6.112 * temp * humidity * 2.1674) / (273.15 + temperature); //simplified version + return (6.112 * temp * humidity * mw) / ((273.15 + temperature) * r); //long version +} + +#define SAVE_PERIOD 30 + void Sgp30Update(void) // Perform every second to ensure proper operation of the baseline compensation algorithm { sgp30_ready = 0; - if (!sgp30_type) { - if (sgp.begin()) { - sgp30_type = 1; -// AddLog_P2(LOG_LEVEL_DEBUG, PSTR("SGP: Serialnumber 0x%04X-0x%04X-0x%04X"), sgp.serialnumber[0], sgp.serialnumber[1], sgp.serialnumber[2]); - AddLog_P2(LOG_LEVEL_DEBUG, S_LOG_I2C_FOUND_AT, "SGP30", 0x58); + if (!sgp.IAQmeasure() || !sgp30_type) { + // retry to init every 100 seconds + if (21 == (uptime %100)) { + sgp30_Init(); } - } else { - if (!sgp.IAQmeasure()) return; // Measurement failed - sgp30_counter++; - if (30 == sgp30_counter) { - sgp30_counter = 0; + return; // Measurement failed + } + if (global_update) { + // abs hum in mg/m3 + sgp30_abshum=sgp30_AbsoluteHumidity(global_temperature,global_humidity,TempUnit()); + sgp.setHumidity(sgp30_abshum*1000); + } + sgp30_ready = 1; - uint16_t TVOC_base; - uint16_t eCO2_base; + // these should normally be stored permanently and used for fast restart + if (!(uptime%SAVE_PERIOD)) { + // store settings every N seconds + uint16_t TVOC_base; + uint16_t eCO2_base; + + if (!sgp.getIAQBaseline(&eCO2_base, &TVOC_base)) return; // Failed to get baseline readings +// snprintf_P(log_data, sizeof(log_data), PSTR("SGP: Baseline values eCO2 0x%04X, TVOC 0x%04X"), eCO2_base, TVOC_base); +// AddLog(LOG_LEVEL_DEBUG); - if (!sgp.getIAQBaseline(&eCO2_base, &TVOC_base)) return; // Failed to get baseline readings -// AddLog_P2(LOG_LEVEL_DEBUG, PSTR("SGP: Baseline values eCO2 0x%04X, TVOC 0x%04X"), eCO2_base, TVOC_base); - } - sgp30_ready = 1; } } + +#ifdef USE_WEBSERVER const char HTTP_SNS_SGP30[] PROGMEM = "{s}SGP30 " D_ECO2 "{m}%d " D_UNIT_PARTS_PER_MILLION "{e}" // {s} =