Hi, Sorry was quite busy lately. I am located in Germany Stuttgart Area near Renningen/Boeblingen FYI: The replaced sensor is still running fine after ~3 Month now. Will update if it goes bad. I can still offer to send/give the broken sensor to you.
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Hi, thanks for the reply. Regarding question 1: All of the sensors are installed indoors. Three of those in directly adjacent rooms to the bathroom. I usually have all doors completely open to the adjacent rooms (except when showering) which provides free air circulation. All sensors are at same height of 1.4m mounted in a slotted casing 1cm from the wall (internal, wall, not perimeter wall). Casing and mounting method see photos in previous post. I checked the correct temperature / offset as follows (All methods showed 3.5....4.5 Degree offset to the affected sensor, affected sensor always reading a too high temperature): Using an IR thermometer measuring the surface temperature of the casing Using an analog thermometer Replacing the BME280 module with a brand new one (which then showed the correct temperature) Comparing to Sensor readouts of the other three BME sensors in adjacent rooms with free air circulation Regarding question 2: The Humidity value also reads a way too low value If I remember correctly (I did not make protocol for humidity): When showering: I read about 65% RH and 35 Degree Celsius, When in reality it should have been >80% RH and 30 Degree Celsius Regarding question 3: A week ago, I replaced the affected sensor module in the bathroom with a new one. This now shows the correct temperature (4 degrees lower) again (as did the affected sensor for ~3 month). I just now swapped the sensor module in the living room with the affected sensor module (Which I stored in a plastic box for 1 week now), to see if outside of bathroom environment the temperature offset is still there: Original living room sensor: 22.5 Degree Celsius, 62% RH Living room sensor with BME280 module from bathroom (after 3 minutes wait time to acclimatize): 25.4 Degree Celsius, 50% RH I will still keep the affected sensor module. If you are interested, I can send it to you.
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Short update: I made some pictures, on how I physically positioned the Sensor in the Casing and on the wall. I also took the opportunity when I had the case disassembled, to swap the Sensor with a new one. After the swap the new sensor as expected reads the correct temperature again (as did the old sensor for 3 months). From this I conclude the issue is not from any ambient heat source, but sensor degradation over time. Now let's see if the new sensor also degrades over time. I would be happy on any feedback on this. Is the way I mounted the sensor OK for a humid Bathroom environment (I let the sensor face downwards to avoid any condensation forming on and dripping into the sensor)?
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Hi, Problem Statement: I am using in total 6 BME280 sensors In my smart Home setup. Initially the sensors worked fine with accurate temperature and Humidity readings. However after ~3 Months one of the sensors suddenly shows a much too high temperature. The temperature is about 4 Degrees higher than the other sensors (e.g. 28 degree instead of real temperature of 24 degree). This also causes invalid/too low humidity readouts (as temperature is used to calculate relative humitidy) The other 5 sensors work fine with the same hardware setup and software. Technical Details: The affected sensor is positioned in the Bathroom (which will sense a humidity change from 30% to 85% to 30% each day during showering) and controls the Fan to blow humid air out of the room. I sample sensor values every 5 seconds. Regarding PCB layout, I am using the Breakout boards with integrated 5V regulator and level shifter commonly found on Amazon or Ebay. The sensor is mounted Head-down (metal casing pointing towards the floor) inside of a Plastic casing with slots to allow free airflow. I am using the Bosch BME driver software v3.5.0 on AVR controller. This is how I initialize the device (Weather monitoring mode): ....
struct bme280_dev m_dev;
m_dev.intf_ptr = &m_i2c;
m_dev.intf = BME280_I2C_INTF;
m_dev.read = IicCWrapper::smRead_c_wrapper;
m_dev.write = IicCWrapper::smWrite_c_wrapper;
m_dev.delay_us = Bme280::delay_us;
/* Recommended mode of operation: Weather monitoring */
m_dev.settings.osr_h = BME280_OVERSAMPLING_1X;
m_dev.settings.osr_p = BME280_OVERSAMPLING_1X;
m_dev.settings.osr_t = BME280_OVERSAMPLING_1X;
m_dev.settings.filter = BME280_FILTER_COEFF_OFF;
m_dev.settings.standby_time = BME280_STANDBY_TIME_1000_MS;
uint8_t settings_sel = BME280_OSR_PRESS_SEL;
settings_sel |= BME280_OSR_TEMP_SEL;
settings_sel |= BME280_OSR_HUM_SEL;
settings_sel |= BME280_STANDBY_SEL;
settings_sel |= BME280_FILTER_SEL;
... Questions: It shis a known issue? Did I do something wrong, e.g. use the sensor outside of its spec? Does the sensors intended use cover usage inside a Bathroom to control the room ventilation? Might this be related to the affected sensor being exposed to numerous humidity changes as ist is situated in the bathroom? Is this a defective sensor? If I replace the sensor, will it show the same problem after 3 month? Thanks for looking into this 🙂
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