The Sensirion Wearable Development Kit also gives the ability to log data to the integrated flash memory. Be aware that closing the SensiSmart app disables the backpack and thus it stops logging. In the picture below a schematic explains how the logging works. As soon as logging was activated in the logging screen, the SensiSmart app sends a logging command to the backpack. This command contains a frame which defines the values to be logged. In the Backpack the logging will be started and the selected data is written to the integrated flash memory.

Please note that this tutorial is written for Microsoft Windows, but the Python download script is platform independent and will also work on macOS and Linux.

Start Logging

• Connect to USB
• Start the SensiSmart app
• Wait until "Not Connected" info screen disappears
• Go to the "Logging" screen:

• Press the middle button and wait for 70s (needed to clear the flash data):

• After the 70s the text changes to “Press mid button to start logging”
• Press the middle button to start logging:

• To stop logging press the middle button again:

Read Out Logged Data

To get the data follow these steps carefully:

• Stop logging on the watch
• Close the SensiSmart app with a long press on the left button (“back button”) 
• Connect to USB via the micro-USB connector
• If not already done, manually install the Arduino USB drivers from the provided .ZIP file ("arduino_driver.zip). The device will be displayed in the device manager as “USB IO Board” or similar, after driver installation it is recognized as “Arduino Micro”.
• Look for the COM port in the device manager (“Arduino Zero” is the device name)
• Variant A – Use your own Python installation:
  • Install Python 2.7 including pyserial
  • Call via the cmd prompt the script with the according COM port, e.g. ‘python wdk_logdata_downloader.py COM15’

• Variant B – Use the precompiled Python packaged .exe file:
  • Change the COM port in the "Sensirion_WDK_logdata_downloader.bat" file
  • Execute the .bat file

The logged data should be stored in a new .csv file in the subfolder “data”.