I have not done much circuit wiring. On the 702, there are four output pins. There are four output pins labeled as W S E N to get information on which receivers see a signal. If I am correct, the line will be either 0 or 1 for each of the 4 pins. If I connect a one wire (of a two wire pair) to W, then to complete a circuit, I will need to connect the the other wire to ground. Where is the best place to connect to ground - the negative side of the 9V pattery that I plan to use?
I would like to connect the four sets of wired to four digital inuputs on a Vex microprocessors. Are there likely to be any problems doing this?
There are ground pins right next to the four outputs. Also, your power supply ground has to be that same ground, so your ground would typically already be connected unless you are using a separate supply just for the beacon.
I was working with a friend who is a EE and he suggested that we put a jumper in to connect the “+” from the battery to to Power Enable. We did this on both transcievers and connected one of the transcievers to to an oscilloscope. The oscilliscope was connected to the “N” signal and ground lines. We connected the other transciever to a 9V battery. We then connected the battery to the first transciever which was connected to the scope. All we saw was a constant voltage on the scope. I think it was about 3.3 volts (but I am not sure). We expected to see a train of pulses.
Should we remove the jumper or is there something else to check?
You might want to smack your EE friend. The enable line is pulled up, so you don’t have to connect anything if you aren’t interested in enabling and disabling the beacon on the fly. More importantly, that line is a digital input going to a digital I/O line on a microcontroller, and if you connect 9V to it, you could destroy your beacon.
It also sounds like you don’t really understand what the beacon does. The microcontroller on the board takes care of broadcasting and receiving, and it decides where the signal is strongest, and enables the corresponding output. There are red LEDs on the outputs, which change slowly, so you won’t see much more on an oscilloscope than you will see on the LEDs. When you apply power, the four LEDs should light up in sequence, and then you should see the green flicker as the beacon transmits. The LED in the direction of the other beacon should light up.
And, just to be really clear, you have to solder in the sensors for the board to work.
You can also use a cheap digital camera or a cell phone camera to look at the boards to verify that they are transmitting IR.
