Member #115584

Member Since: January 17, 2010

Country: United States

  • The code has analogWrite to pins 8 and 13. Those are not PWM pins on the RedBoard. I wanted to slow the motors down to stop them from slipping on the wood floor. This didn’t work until I moved pin 8 to pin 3 and pin 13 to pin 5. Then I could slow the motors.

  • Neat demonstration. Explanation should be “commutative” rather than “communiative”.

  • Since we left the competition way back there, Sparkfun has nothing to worry about now.

  • In the video, it was stated that the IR was not visible to “Greg’s really fancy camera” until a pair of polarizing sunglasses were introduced. It was also stated that the cell phone camera worked because it contains a polarizing filter. I wish this had been explained. I suspect that something other than polarization is going on here.

  • Why does the polarizing filter make the IR light visible to the camera?

  • Yes. Define the oscillator as P181 in the UCF file and as an input in your code. Things should work.

  • The description includes the words “exponential decay” and the equation is exponential decay, but the voltage is growing to an asymptotic value, not decaying to zero. The equation for the red line should be V(t)=V_in[1-exp{-t/RC}]. The equation Vt)=V(0)exp{-t/RC} will work for the second half of the source signal cycle. Very nice presentation.

  • This thing is not very accurate, as others have noted. However, the one I have is very stable. Using this device to produce an accurate time requires a little software to remove the drift. If you do this, it’s better to let the clock drift and compute a correction than to occasionally reset the clock. Two of the 56 ram bytes can be used to store a reference time. I have a clock that is working well with this approach.

  • I had inconsistent results with smaller caps and ended up using 3.3 uF. That’s been working fine for me.

    If you want to load with the reset button, it works to hold the button down, upload the code, and then release the button the instant that you see the TX LED on the FTDI board light up. That also seems to work consistently, but the capacitor is easier.

  • Should that be 2.5x100mm?

No public wish lists :(