Lab Report 07

This week (May 18-25):

• The sensors and microprocessor were wired up and tested with battery power. This was a success.
• One problem: the PM sensor is apparently extremely sensitive to light. If the sensor is not in a dark environment, the readings become junk. We will try to address this:
  • Check if the uncut-PM sensor has the same issues. If not, enlarge the housing to hold the uncut-PM sensor.
    • Update (5/25/15, 11:30 PM): The cut-PM sensor was swapped out with the uncut-PM sensor. The first five datapoints from the sensor did not make sense, but the following 100+ datapoints were all within reason. This suggests that there were some bad values in the accumulator on the on-board DSP chip, likely thermally induced during the soldering process. All subsequent values are within reason, even after rebooting the sensor.
    • The PM sensor’s data is inherently noisy as it uses an optical method coupled with a high gain amplifier. To mitigate this, the Arduino takes 15 PM samples and reports the average to the Android phone.
  • Change the air flow from a straight path to a curved one. This would block direct light while allowing some air through
• The Android app was merged (Bluetooth and front end)
  • The front end was merged piece by piece into the Bluetooth projct.
    • The grid-view for 24 hours of data was removed (the grid was a mockup; incomplete, therefore removed)
    • The grid-view for 24 hours was replaced with a moving average of 24 hours.
  • The full app is tested and debugged (with mocked sensors from the Arduino side, for convenience)
    • The phone used was the Infocus M210.
    • We will load the app on the Samsung Galaxy S4 and Huawei Honor 3X this week.
  • Remaining improvements include:
    • Saving sensor data locally in case the WiFi connection is lost
    • Adding appropriate Toasts for various levels of particulates/VOC/humidity
• First draft of Final Product Requirements Document complete