Robots w/Lasers

July 17, 2007

Heart Monitor for NDS

I have a prototype of the hardware side of my Nintendo DS-based heart rate monitor. I’m using the awesome DSerial to interface an IR LED & IR phototransistor to the DS.

It works ok, but the signal is not strong enough. Slight movements can make the data unusable. I think I need to work on either amplifying the signal, or increasing the sensitivity of the DSerial. Also I need to rig up some velcro to stick the sensor to your finger, so you don’t have to hold it in place.

Here you can see my “sensor”:

Here is the connection to the DS:

And finally, here is a screenshot of the DS’s lower screen, which is just graphing the data coming from the DSerial’s ADC:

Check out this movie of it in action: dserial_heart_monitor.avi (1.5MB)

Filed under: DSerial,Hardware,Nintendo DS — davr @ 12:29 pm

June 29, 2007

Hardware I/O for Nintendo DS


A neat-looking device for DS homebrew development is natrium42‘s DSerial. The features include

  • 8051 microcontroller running at 24MHz
  • Reprogrammable from DS, premade firmwares available
  • Free development tools available
  • 18 GPIO lines, 2 status LEDs
  • UART with RS-232 level converter (can be disabled)
  • Full-speed USB 2.0 device (does not support USB host)
  • PWM and ADC available
  • 2D tilt sensor

I’m hoping to make some cool stuff with it…my first plan is to build a portable heart monitor, that can also tell you how stressed-out you are, based on your ‘coherence’ (essentially you take the FFT of your heart rate over time, and you want most of the energy to fall near to 0.1Hz)

Filed under: DSerial,Hardware,Nintendo DS — davr @ 12:37 pm

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