SparkFun Forums

[khoma]

Hi

I'm building a tracker using a FONA 808 (https://learn.adafruit.com/adafruit-fon ... t/overview) to which I have a LiPO connected. It in turn is connected directly to an arduino pro mini, to the raw pin. I would like to use a Wake on Shake to signal an interrupt using the digital pin #3 on the arduino, rather than having the Wake on Shake power it. Thus I have connected the VIN on the WoS to the VCC of the Arduino, and the VOUT of the WoS to the digital pin #3 of the arduino.

It does not seem to be working though, even after the WoS goes to sleep (I use the serial console issuing the z command to be sure) the voltage on the VOUT pin of the WoS remains at 3.3V. It does eventually go down to 0V but it takes minutes, not the 5 seconds to which it is set by default. Like 1-2 minutes after the unit goes to sleep it will lower the voltage on VOUT. The WAKE pin is connected to digital out #11 of the pro mini, and it is set to LOW.

Is there some strange way in which I could have crossed some wires that could cause this behavior?

Edit: It does appear as though the shake sensor is working, since once it finally lowers the voltage I can turn it back on by moving it around a bit.

[khoma]

Seems I can only edit once so here's an update. I was wrong earlier, the voltage doesn't remain at 3.3V, rather it seem to fluctuate around 0.7V, which unfortunately is enough for the arduino to read a HIGH signal on that port. Is this 0.7V in sleep mode normal behavior?

[darrellg]

Try putting a 10K pull-down resistor between pin 2 and GND.

[khoma]

Thank you! Works like a charm now, at least from preliminary testing. Now onto breaking something else! =)