Device | Blueprint | Timezone | Batch | Mode / Period | Active / Passive |
---|---|---|---|---|---|
14687 | SCK 21 | Europe/Madrid | First batch | One-shot / 15s | Active |
14688 | SCK 21 | Europe/Madrid | First batch | One-shot / 15s | Active |
14769 | SCK 21 | Europe/Madrid | New batch | One-shot / 30s | Active |
14842 | SCK 21 | Europe/Madrid | First batch | Continous | Active |
14843 | SCK 21 | Europe/Madrid | New batch | Continous | Active |
14850 | SCK 21 | Europe/Madrid | New batch | Continous | Active |
14851 | SCK 21 | Europe/Madrid | New batch | Continous | Active |
14853 | SCK 21 | Europe/Madrid | New batch | Continous | Active |
14854 | SCK 21 | Europe/Madrid | New batch | One-shot / 30s | Active |
14855 | SCK 21 | Europe/Madrid | New batch | One-shot / 30s | Active |
14885 | SCK 21 | Europe/Madrid | New batch | One-shot / 35s | Active |
14888 | SCK 21 | Europe/Madrid | New batch | One-shot / 35s | Active |
14889 | SCK 21 | Europe/Madrid | New batch | One-shot / 30s | Active |
14946 | SCK 21 | Europe/Madrid | New batch | One-shot / 15s | Active |
14947 | SCK 21 | Europe/Madrid | New batch | One-shot / 15s | Active |
14948 | SCK 21 | Europe/Madrid | New batch | One-shot / 15s | Active |
14949 | SCK 21 | Europe/Madrid | New batch | One-shot / 15s | Active |
14994 | SCK 21 | Europe/Madrid | New batch | 15s | Passive |
14995 | SCK 21 | Europe/Madrid | New batch | 15s | Passive |
14996 | SCK 21 | Europe/Madrid | New batch | 15s | Passive |
Below is a description of each device, finding documentation and data sources.
Channel | Units | Type (raw/processed) | Algorithm | Description |
---|---|---|---|---|
BATT | % | Raw | n/a | Device battery status |
CCS811_ECO2 | ppm | Raw | n/a | Equivalent CO2 |
CCS811_VOCS | ppb | Raw | n/a | total Volatile Organics Compounds |
HUM | %rh | Raw | n/a | Urban board humidity (SHT31) |
LIGHT | lux | Raw | n/a | Urban board ambient light |
NOISE_A | dBA | Raw | n/a | A-scale noise SPL |
PM_1 | ug/m3 | Raw | n/a | PM1 measurement from PMS5003 |
PM_10 | ug/m3 | Raw | n/a | PM10 measurement from PMS5003 |
PM_25 | ug/m3 | Raw | n/a | PM2.5 measurement from PMS5003 |
PRESS | kPa | Raw | n/a | Atmospheric pressure |
TEMP | degC | Raw | n/a | Urban board temperature (SHT31) |
This note tries to shed some light on the recent issues found with the Plantower PMS5003 sensor in the SC project. Two issues were identified:
An issue has been identified with how the readings are taken from the PMS5003. This issue is analysed first, as it has no relation at all with the new batch of the PMS5003 zero readings issue. This is related to how the readings are requested to the PMS5003 sensor: a bug in the firmware, which was fixed in this commit, made the SCK to not discard the initial readings accumulated in the serial buffer coming from the PMS5003. This meant the readings were actually not the readings from 15s after the sensor was turned on, but likely after some few seconds (1 or 2) after turning on the PMS. The blue trace in the graph below shows the corrected output, versus the readings before the fix (in orange). As seen in the graph, this lead to:
An analysis of the 15s one-shot interval is done in this part. The 15s one-shot mode means that the sensor is turned on only for 15s in order to take a measurement, and that the rest of the time is switched off for battery saving purposes. The reading (ideally, see above) is taken after 15s of being turned on, in "one-shot" mode. This method has been evaluated in this AN. In order to re-assess the validity of this mode, two units are tested in one-shot 15s mode, and compared against the readings of one unit in continuous mode. The figure below shows the comparison.
In parallel to this test, a comparison between sensors of the new and old batches is done. Three sensors of the first batch in one-shot mode at 15s are compared against 5 sensors of the new batch. The figure below shows a clear gap between the readings in all reading levels.