After updating the firmware to the latest, i have noticed the air pressure is no longer accurate. Its values change greatly at each refresh.
Within the space of 10 seconds the pressure reads:
1015, 1010, 1019, 1014 etc
I can’t remember precisely, but i think it was much more stable before the update, ie the value would not change this much within a few seconds.
As it is the barometer is unusable as between 1010 and 1019 there is quite a lot of difference and readings are totally random.
The same although to a lesser degree is happening to the temperature, readings change continuosly, 22.1, 22.6, 23.3 in the space of few seconds.
Lastly, not sure if it was a coincidence but i have found the tvoc often maxed out, as if it is creeping up gradually after i restart the unit.
@VEL342 could it be the firmware update that has made the sensors refreshing too quickly?
Yes i have now checked, within a few hours from switching on, both co2 and TVOC get to the max of their scale. Air in my house has not changed and it is not polluted so it must be a software/hardware issue.
I have also placed the unit outdoors and still both the co2 ans tvoc are very high (red range) which shows that there is an issue with the software
Most of the firmware changes between the shipped version and the latest version are for the lightning sensor en do no affect the air quality sensor (temp, humi, pressure, tvoc and eCO2). Please note that the sensor needs up to 20 min to calibrate. However, it is very unusual that the pressure and temp values change that rapidly. Please check your connections and make sure the SDA/SCL wires are connected well.
To be absolutely sure, you can always revert to the older firmware to check if this is more stable for your device.
I will check the wires. Btw have you got a reference pictures where these cables (and their colours) and their position is visible, so to make it easier for me?
I have however not changed the position of the wires since I assembled it, this is why i thought it was a firmware issue).
I will keep you posted.
I have checked the wires, they seemed to be all well connected, however to be on the safe side i gave them a little wiggle. This fixed the issue. It appears that with these wires/connectors there might be a false contact even if the connector is fully engaged. Perhaps a slight bend changes the contact. Anyway, @VEL342 you have resolved the issue and now co2, tvoc are back to normal values, and pressure and temp now have very slightly changes in the order of 0.5 units max.
Spoke too soon.
While the tvoc and co2 still work fine, the pressure is still oscillating. At every refresh it varies from 1017 to 1024.
The strange thing is that at the beginning, after a reboot, the pressure is very stable. However within 30 minutes it starts going up and down.
This suggests jt is a software problem, not hardware.
@VEL342, have you got any idea on why this could happen?
The wires are not the issue, i thought i had sorted the problem only because after the reboot the values are more stable.
I have a suspicion. It might be the power source. When i use the unit connected to the laptop’s usb the value is more stable. If i connect the unit to a usb hub, which has variable current/milliamperes output, the value becomes unstable. Could it be that the variable current makes the pressure sensor report oscillating values?
If the values are stable at the beginning and 30 min later they are not, that’s not normal behaviour and has nothing to do with the software.
Like you said in your last post, this might be a power issue.
The sensor board has an internal power regulator, converting the 5VDC power to 3V3. If the main power supply of 5VDC is not suitable, it might result in a drop to 4.8 VDC or even lower, making the 3V3 power drop below 3VDC. That in turn will disrupt the sensors, hence the bad read-out.
We recommend a power supply of at least 5VDC 1A (5W) or higher. Since you added a RTC module and an RGB LED, 2A would be advised.
It is indeed that at the beginning the values are very stable, then they go all over the place. The temperature and humidity are the most stable, whereas the tvoc, co2 and air pressure are those that show the biggest change. I have tried several power sources but i have not yet confirmed if the different types make any difference. It is odd however that at the beginning they are fine and then they stray, as if it was a low power issue the problem will show immediately after the rebook?
Why is there a change after 30min?
If a power source is unsuitable, it should be from the start, not after 30 minutes?
Btw, the vma301 doesn’t work, i have connected it properly, and my software is V4.2 (see other post re clock).
@VEL342 i have finally resorted to using a huawei power charger which delivers 2A fixed. My usb hub could deliver up to 2.4A but thats variable and probably was causing oscillation. It has been running for 2hrs and is very stable. It was indeed the power source causing the issue, as the vm211 is very fussy about which type is used.
Now it remains to be established why the rtc vma301 doesn’t work, despite being correctly installed…
Most power supplies will try to give the higher demand of power but will give in after some time. Also, the EarthListener will heat up gradually and demand more power. Maybe that’s why the values start “dancing” after 30 min.
Glad to hear you have solved this with a stronger power supply.