Problem getting BMP180 to show correct readings.

[royson84]

So as the topic says, im having problems getting a working sketch to my BMP180. It shows some really weird readings:

Temperature = 200.30 *C
Pressure = 108908 Pa
Altitude = -613.66 meters
Pressure at sealevel (calculated) = 108914 Pa
Real altitude = -599.14 meters

I've tried the "sensorapi" sketch from "Adafruit BMP085 Unified" and the "BMP085test" från "Adafruit BMP085 Library".

Its connected like the guide says:
VIN<->3.3V
GND<->GND
SCL<->A5
SDA<->A4

My plan is to use this on a node together with a UV sensor and a DHT22.
Anyone how wants to take a shoot at what im doing wrong? Cause I suspect thats the case....

Thanks.

[mfalkvidd]

@royson84 with that temp and altitude I would guess that you're in Hell I hope that's no the case.

How are you powering the BMP180? (where does 3.3V come from?)
Can you test with a different Arduino?
Can you test with a different BMP180?
Do you get the exact same value for every reading, or do they vary (if you heat the sensor with your hand for example)?
Do you get the exact same value from the two libraries?

[royson84]

@mfalkvidd said in Problem getting BMP180 to show correct readings.:

@royson84 with that temp and pressure I would guess that you're in Hell I hope that's no the case.

How are you powering the BMP180? (where does 3.3V come from?)

Its now connected to an UNO that is powered from USB on my laptop. It get around 4V when a measure with multimeter. Might that be the problem? Will that destroy the poor little thing?

Can you test with a different Arduino?

Might have a Pro mini to give it a shot with.

Can you test with a different BMP180?

Nope, only bought one so far.

Do you get the exact same value for every reading, or do they vary (if you heat the sensor with your hand for example)?
Do you get the exact same value from the two libraries?

Same value from both libraries and sketches. And since the temp is 200C, I think I might have a difficult time getting another reading in my hand, but I'll give it a shot

[mfalkvidd]

@royson84 the adafruit description says

connect the VIN pin to the 5V voltage pin

and

Vin: 3 to 5VDC

so I think any voltage between 3 and 5V will work.

[royson84]

@mfalkvidd said in Problem getting BMP180 to show correct readings.:

@royson84 the adafruit description says

connect the VIN pin to the 5V voltage pin

and

Vin: 3 to 5VDC

so I think any voltage between 3 and 5V will work.

Ok. Gonna give it a shot tomorrow with a Pro mini and see if that gives any different results.

[royson84]

It seems like the sensor might be broken. Tried it just now with the library from Sparkfun following this guide: https://learn.sparkfun.com/tutorials/bmp180-barometric-pressure-sensor-hookup-

BMP180 Init fail. The sensor is powered but that seems to be about it. Big disappointment.

[gohan]

Maybe get a bme280 next time

[royson84]

@gohan I might just do that. Any seller to recommend?

[gohan]

@royson84 https://www.aliexpress.com/item/High-Accuracy-BME280-Digital-Sensor-Temperature-Humidity-Barometric-Pressure-Sensor-Module-GY-BME280-I2C-SPI-1/32672210336.html

This is what I got. Keep in mind that bme280 tends to report temperatures 0.7/0.8C higher than actual, so make a comparison and add a temperature offset in code