Hello, I have the sensor all plugged in and working.
I have been experimenting with powering it through the USB and using batteries and a 5v voltage regulator through the VIN.
When I first powered it up I was getting readings around 2000 using the code posted on the seeedstudio wiki page.
But now with basically the same code I am getting readings of around 10000 to 20000, which is far in excess of the stated max of 8000, especially considering I am only in my office or my flat. I have it in the correct orientation, facing up. I have taken it outside to a dusty environment (where it registered up to 50000!) so I am not sure if that has affected it? I don’t think it is the power setup as the results are pretty consistent across different power setups and two sketches (one straight logging via Serial, the other using adafruit GPS shield to log on an SD card and Serial) although USB powered logging via Serial with no GPS does seem higher than the other setups.
I really need to be able to trust these results for a project!
Thanks in advance for any advice,
David
Here is some of my data:
LOG ONLY: 8xAA all VIN
concentration = 17086.59 pcs/0.01cf
concentration = 17224.57 pcs/0.01cf
concentration = 16326.93 pcs/0.01cf
concentration = 14902.90 pcs/0.01cf
concentration = 15972.16 pcs/0.01cf
concentration = 18150.88 pcs/0.01cf
concentration = 15456.62 pcs/0.01cf
concentration = 16486.91 pcs/0.01cf
concentration = 16491.43 pcs/0.01cf
concentration = 16847.23 pcs/0.01cf
concentration = 14667.15 pcs/0.01cf
GPS: 8xAA all VIN
concentration = 14842.41
concentration = 18444.53
concentration = 13996.59
concentration = 11295.74
concentration = 16738.35
concentration = 14006.66
concentration = 15787.97
concentration = 20504.10
concentration = 18216.31
concentration = 15258.73
concentration = 12982.25
concentration = 15763.43
concentration = 11855.86
concentration = 17325.02
concentration = 14291.75
concentration = 12615.11
concentration = 8465.27
concentration = 8434.38
concentration = 10529.63
concentration = 9172.25
concentration = 9885.07
concentration = 10520.47
concentration = 7407.08
concentration = 9952.56
concentration = 10962.48
concentration = 10919.64
concentration = 11092.27
LOG ONLY: 4xAA all VIN
concentration = 14999.24 pcs/0.01cf
concentration = 13983.44 pcs/0.01cf
concentration = 14235.22 pcs/0.01cf
concentration = 13880.61 pcs/0.01cf
concentration = 14353.96 pcs/0.01cf
concentration = 13530.92 pcs/0.01cf
concentration = 14909.16 pcs/0.01cf
concentration = 14433.64 pcs/0.01cf
concentration = 13853.90 pcs/0.01cf
concentration = 14341.53 pcs/0.01cf
concentration = 12971.75 pcs/0.01cf
concentration = 14517.75 pcs/0.01cf
concentration = 14747.89 pcs/0.01cf
GPS: 4xAA all VIN
concentration = 10519.85
concentration = 11360.30
concentration = 10737.04
concentration = 13227.68
concentration = 14134.87
concentration = 11018.77
concentration = 13208.04
concentration = 11342.29
concentration = 9328.30
concentration = 10571.31
concentration = 12089.90
concentration = 11238.18
LOG ONLY: USB
concentration = 14253.66 pcs/0.01cf
concentration = 14280.59 pcs/0.01cf
concentration = 15234.94 pcs/0.01cf
concentration = 21366.34 pcs/0.01cf
concentration = 18223.91 pcs/0.01cf
concentration = 18094.00 pcs/0.01cf
concentration = 15211.91 pcs/0.01cf
concentration = 18692.63 pcs/0.01cf
concentration = 17902.22 pcs/0.01cf
concentration = 14717.79 pcs/0.01cf
concentration = 15404.01 pcs/0.01cf
concentration = 13357.14 pcs/0.01cf
concentration = 14377.32 pcs/0.01cf
concentration = 13438.01 pcs/0.01cf
concentration = 12629.28 pcs/0.01cf
GPS:USB
concentration = 11376.73
concentration = 11363.76
concentration = 13586.34
concentration = 13737.12
concentration = 10871.82
concentration = 10651.04
concentration = 12101.42
concentration = 12987.53
concentration = 16563.69
concentration = 13404.50
concentration = 8953.62
concentration = 16554.08
concentration = 15247.16
concentration = 14127.41
concentration = 12536.62
concentration = 10399.76
I’ve done a lot of testing and found that the GPS shield was interfering with data coming in on pin 8. So I have added another arduino, this one to measure the dust particles, and then send it to the other arduino with GPS shield to write it to the SD card.
This works OK indoor, but if I take it outside I am again getting very high results that exceed 8,000.
Does anyone have know if it should max out at 8,000 and not give higher results? Or if it is OK to go above 8,000 but you need to house it in a specific box to use the sensor effectively outside?
Thanks in advance for any help!
