[Barrow4491]

I have attached a photo. I assume the regulator is faulty

Even without any part installed on the board, the output voltage of the regulator, is still 5.97V?

Yes it is

[Palmyweather]

I have checked all connections (not that there are many) and all seem OK, and have tried with only the HTU21D and PMS7003 and still no result. I have even replaced the Nano with a new one.
I have a few observations which may give you a clue;
Input voltage measures 9.19v, regulator output 5.97v, the "L" led on the nano is constantly on, there is a regular red flash internally from the CO2 sensor and the fan in the PMS7003 never seems to move and i have not seen the Tx led flash.
I am at a loss!! 
Regards
JIm

Hi Jim

On my very first day of powering up the Air Quality board, I had similar results to what you mention above: A regular red glow from the CO2 sensor, LEDs illuminated on the Nano but nothing else worked. I would not get any flashing TX light or data upload.

My solution was I found that I had connected the quick connector pins around the wrong way on the PMS7003 at the sensor itself. When I unplugged and turned it around the correct way, everything came to life.

Not sure if this is the same situation as to what you are facing however. I attach a photo of the plug I got with my PMS7003 and you can see how easy it would be to get around the wrong way.


   

[Barrow4491]

I have checked all connections (not that there are many) and all seem OK, and have tried with only the HTU21D and PMS7003 and still no result. I have even replaced the Nano with a new one.
I have a few observations which may give you a clue;
Input voltage measures 9.19v, regulator output 5.97v, the "L" led on the nano is constantly on, there is a regular red flash internally from the CO2 sensor and the fan in the PMS7003 never seems to move and i have not seen the Tx led flash.
I am at a loss!! 
Regards
JIm

Hi Jim

On my very first day of powering up the Air Quality board, I had similar results to what you mention above: A regular red glow from the CO2 sensor, LEDs illuminated on the Nano but nothing else worked. I would not get any flashing TX light or data upload.

My solution was I found that I had connected the quick connector pins around the wrong way on the PMS7003 at the sensor itself. When I unplugged and turned it around the correct way, everything came to life.

Not sure if this is the same situation as to what you are facing however. I attach a photo of the plug I got with my PMS7003 and you can see how easy it would be to get around the wrong way.

Hi,
Thanks for your input, but I realised early that the plug was reversible so I hunted the web for a data sheet to get a pinout of the sensor and the correct orientation is with the small pcb overhanging the sensor as the photo of your installation shows.
I am away for a month and will sort it out when I return (the regulator is faulty I am sure)
Regards
Jim

[Barrow4491]

[attachment=1215]Hi,
Have returned from my holiday and am trying to sort out my AQI issues. I decided to replace the regulator on the board and try again.
Instant success, the LCD came to life with the boot procedure (I noticed the software was version 5) followed by the screen for data (PM 2.5, PM 10, CO2 and AQI index and temp and Rh values. this lasted for about 10 minutes and the LCD went very bright with no data and after turning it off and unplugging all sensors the regulator was again very hot and was faulty again.
Not to be deterred i replaced the regulator again and reloaded with V6 software and turned it on with no sensors plugged in and it came to life again with the 5 volt rail reading 4.9 volts
I plugged the sensors in one at a time with no issues until it came to the HTU 21D but it refused to reboot. Unplugging the module solved the problem and it rebooted OK. It has now been running for 20 hours with no regulator issues.
 See the attached screen shots
Some issues;
1   I then noticed that the HTU21D sensor has a maximum vcc of 3.9 volts but the circuit provides 5 volts. I have searched the internet looking for a 5 volt version to no avail, and as per the screen shot the temp and Rh values are 998.0 because of the lack of a sensor.
2   The values for PM 2.5 and PM 10 are negative and the AQ Index value is 0
3   It took overnight ??? for any values to appear in my Rx and only the CO2 is shown.
Any assistance to resolve these issues would be greatly appreciated
Regards
Jim

[werk_ag]

Hi Jim,

Not to be deterred i replaced the regulator again and reloaded with V6 software and turned it on with no sensors plugged in and it came to life again with the 5 volt rail reading 4.9 volts
I plugged the sensors in one at a time with no issues until it came to the HTU 21D but it refused to reboot. Unplugging the module solved the problem and it rebooted OK. It has now been running for 20 hours with no regulator issues.

Now you know what have damaged the voltage regulator. The original board wasn't defective.
By the way, seems that the new AQM board wasn't arrived yet, so you should get it very soon.

1   I then noticed that the HTU21D sensor has a maximum vcc of 3.9 volts but the circuit provides 5 volts. I have searched the internet looking for a 5 volt version to no avail, and as per the screen shot the temp and Rh values are 998.0 because of the lack of a sensor.

Here is a link to the 5V version, it's very common

https://www.ebay.com/itm/HTU21D-Temperat...SwW9ZZccVf

2   The values for PM 2.5 and PM 10 are negative and the AQ Index value is 0

Check the connections of the sensor with the board. You can activate the debug functions on the software to check if the sensor is being read correctly.

3   It took overnight ??? for any values to appear in my Rx and only the CO2 is shown.

If there are problems reading any of the sensors, you may not receive any data at all. Otherwise, after an initial period of 3 minutes, data is sent to RX, more or less at each 35 seconds.

[Barrow4491]

Werk,
I am aware of that sensor but the issue is that the ground and vcc connections are swapped relative to the pcb and it cannot be plugged in directly to a socket but requires a cable connection. I am trying to keep the unit as compact as possible and avoid extra cabling
Thanks
Jim

[werk_ag]

Well, don't know if that will be a good idea, the readings of the temp / hum sensor will be largely influenced by the heat produced by the Nano and the voltage regulator.
Actually the temperature reading isn't used by the software for any calculation, but the readings of the air moisture are used on the calculations of the PM2.5
Current investigations also seem to reveal that air moisture affects CO2 readings, so in future software releases, the RH may also be used by the CO2 calculations.

[uncle_bob]

I then noticed that the HTU21D sensor has a maximum vcc of 3.9 volts but the circuit provides 5 volts. I have searched the internet looking for a 5 volt version to no avail, and as per the screen shot the temp and Rh values are 998.0 because of the lack of a sensor.

I powered mine from the 3.3vdc pin on the Nano

[Barrow4491]

Uncle_bob,
Thanks for that works out well with my layout
Regards
Jim

[Barrow4491]

[attachment=1229][attachment=1228]

Werk_AG pid='8332' dateline='1511058035']Well, don't know if that will be a good idea, the readings of the temp / hum sensor will be largely influenced by the heat produced by the Nano and the voltage regulator.
Actually the temperature reading isn't used by the software for any calculation, but the readings of the air moisture are used on the calculations of the PM2.5
Current investigations also seem to reveal that air moisture affects CO2 readings, so in future software releases, the RH may also be used by the CO2 calculations.

Werk,

The fact that I had no temperature sensor plugged in i thought may be causing the weird high temp and RH readings, so i disabled the line"use_RH comp" in the config and recompiled and that fixed it, but still no data being sent to the Rx.

I then decided to use the new board, which had since arrived, and powered the HTU21D from the 3.3 volt pin on the nano as suggested by Uncle_bob. Powered it up and everything seemed to be as expected and I am receiving data on the Rx about every 35 seconds or so, except that yesterday the CO2 readings weren't coming through. Ran the serial monitor and it reported that the readings were incorrect, so I have since disabled it and ordered a new one.
The cause of the regulator failure is a mystery as the same temperature sensor on 3 volts is working fine with the new board and it is now transmitting reliably with the same components.
Regards
Jim