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Lost Baro after sensor change
#1
Hi all

I was initially using the BME280 for temp/hum/baro on my RX board. I was unsure of the temp/hum readings of this sensor, they seemed a little high, so I've added a SHT31 sensor to take temp/hum readings from - leaving the BME280 just for baro.

My config is as below, but I no longer have baro/ATM readings on the display. Temp and hum are reading fine.

Code:
// --------------------------------------------------------------------------------------
//   Define the type of your Barometric Pressure Sensor
// --------------------------------------------------------------------------------------
#define BAROMETRIC_SENSOR  0   // 0= BME280, 1= BMP280 2= BMP085 / BMP180


// --------------------------------------------------------------------------------------
//   Define the type of your inside Temperature / Humidity Sensor
// --------------------------------------------------------------------------------------
#define INSIDE_TH_SENSOR   3   // 0= BME280, 1= HTU21D, 2= SHT21, 3= SHT31

WeatherDuino Pro2 PLUS Receiver - Version: P2AT2560_RX_v7.0_b003


Any help would be appreciated to troubleshoot this one, baro was fine until I changed. Is this not a compatible configuration?

Thanks
Colin
41south.net.nz powered by WeatherDuino and Weewx
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#2
Well I'm not sure if there is an answer to the software issue, but I have fixed the erroneous readings by moving the BME280 away from the circuit board using a short extension wire set. I suspect that ambient temperature from the PCB devices was causing the issue, it now reads to with 0.1 deg C of another sensor placed next to it so I'm happy.

I have returned my config to;
Code:
// --------------------------------------------------------------------------------------
//   Define the type of your Barometric Pressure Sensor
// --------------------------------------------------------------------------------------
#define BAROMETRIC_SENSOR  0   // 0= BME280, 1= BMP280 2= BMP085 / BMP180


// --------------------------------------------------------------------------------------
//   Define the type of your inside Temperature / Humidity Sensor
// --------------------------------------------------------------------------------------
#define INSIDE_TH_SENSOR   0   // 0= BME280, 1= HTU21D, 2= SHT21, 3= SHT31

WeatherDuino Pro2 PLUS Receiver - Version: P2AT2560_RX_v7.0_b003

Werk, not sure if the problem I have here needs to be logged somewhere for investigation as a software issue?
41south.net.nz powered by WeatherDuino and Weewx
Reply
#3
Hi Colin

Thank you for describing this particular situation. I understand that it can be seen as software problem, but it isn't. Once the selected T/H sensor is anything else than the BME280, you only get barometric readings if you install an BMP280 (or BMP180) and select it.
The baro, temperature and humidity readings from the BME280 are done at once, in a single statement, so when we are using a different T/H sensor, the baro isn't read.
Of course the code could be write in another way, but since the major benefit of the BME280 is having all the three readings from just one sensor, I didn't separate the read routines.

In any case, to avoid the influence of the internal heat produced by the electronics, the module which contains the indoor T/H sensor (being a BME280 or an SHTxx) should always be placed outside the box where the system is installed. Exactly was you have found!  Smile

Out of curiosity, give a look at the detail of an external housing for the T/H sensor (small box on the back) included on the excellent box designed by Jarekh3 for the WeatherDuino Pro2 Plus receiver.

[Image: ?url=cdn.thingiverse.com%2Frenders%2Ffb%...atured.jpg]
MeteoCercal - Air Quality Data
Click here to watch at my ThingSpeak channel



Reply
#4
Thank you sir, that explains it all Big Grin

Yes that is a nice enclosure, I will see if i can find a good quality 3D printing station nearby.


Regards
Colin
41south.net.nz powered by WeatherDuino and Weewx
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