2016-03-17 (Th) Cyborg Heart Rate Sensor

Programming was added to start activating outputs. The onboard LED was first since it would be easy to troubleshoot. For some reason the output made results very unreliable. No heartbeat could be detected and it seemed to be a problem with the rate at which the program refreshed. The stock program used interrupts to periodically measure output from the sensor whereas this program is simpler and simply measures the sensor as often as possible.

Graph of unusable data 01

Scanning as often as possible didn’t do anything to ensure the measurements happen at regular intervals, in fact, since the keyboard function was being used to output data the time between measurements was directly affected by how many digits were sent as keyboard strokes. Normally a serial connection is used and this also takes advantage of interrupts. Eliminating the keyboard function would greatly speed up the scanning rate but it would also become more difficult to debug since the window into the controller’s world would be closed.

Graph of unusable data 02

Even though the outputs weren’t working the motor would still be easier to control than a coil. The transistor was removed from the motorized version of the project and the motor was soldered directly to Pin 5 which has a 3V output unlike the other pins which use the USB power which is 5V. The hope was that the 3V output could supply enough power to drive the motor. Unforunately this was not the case and the board would not accept any programming while the motor was soldered in place between pin 5 and GND.

Motor soldered to pin 5, 3V output

To do:
  • Program with Digispark
  • Debug 
  • Integrate hardware
    • Coil
    • Vibrator motor
  • Build into glove

The rest of the posts for this project have been arranged by date.

First time here?

Completed projects from year 1.
Completed projects from year 2

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2016-03-14 (M)