View Full Version : Phidgets 888 IO board and Digital input question.

08-04-2009, 04:34 PM
First let me state for the record that I am a noob plus 1 when dealing with some of the electronic information. Programming is my side...

Ok i am working on a project that i want to tell the IO board then a toy lasertag gun took a hit. On the top of the gun is the IR receiver and some LEDs that light up when hit. The gun also shakes for a moment due to a small vibrating motor. These are the guns

Amazon.com: LAZERTAG Multiplayer Battle System: Toys & Games

my question how is the best way to capture the hit from the IO board. I was thinking about connecting to the LEDs or the motor and running one wire to the ground on the board and the other to the digital input. Is that a good or a bad idea. The gun runs on 6 AA batteries, not sure if that matters for this discusstion. There are 4 red LEDs on the top dome of the gun and the ones i would tie into. I do know the wires that supply power to the daughter board that the ir sensor and leds are connected to. I have not yet checked to see if power is there all the time or only when a hit occurs.

If this is a totally wrong approach please let me know. The fire and Shield on the gun i know i can control from the phidgets 2 relay board for the 888 IO board. I am stuck on the input side.

Any help is greatly accepted


08-04-2009, 05:06 PM
Do you have a multimeter?

08-04-2009, 05:10 PM
Yes, still a bit green on how to use some of the settings. I was trying to find a way using ohm side to see if there was something that has no connectivity but when hit by the other gun the connectivity jumped the fell off. Is that what i should be looking for?

08-04-2009, 08:45 PM
I would be looking for voltage. The black wire on the negative lead of the battery, then the red wire looking for something that generates voltage when the gun is hit. Make sure that if you don't have an autoranging multimeter that you're set for something like 20vDC initially so that you don't burn up the meter.

08-04-2009, 08:57 PM
does that mean if i can find the negitive and positive when a hit is register, that that would equal put the ground from gun to the ground of the 888 board and the positve to one of the digital inputs. then pick up the .net event and determine that it came from the input i wired the gun too?

08-04-2009, 10:46 PM
Ok I have found a negative and a positive that only gets power when a hit has been made. It will however stay on when game is over and that gun lost due to too many hits. the voltage is 9volts (6 AA batteries). so now would i tap into those 2 wires and connect the negative one to the ground on the IO board and the positive one to one of the digital inputs? Also will the board support that much voltage? in each hit or when it is on until i recylce the guns due to losing the game?

08-05-2009, 08:06 PM
after re-reading the manual i have to wonder am i to connect this a MOSFET? and if yes can you explain how i think the picture is readable in the manual, but not sure and i do not want to blow the board. also can you recommend the type that i would need?

thanks for any help

08-05-2009, 10:32 PM
When you say 9v, do you mean that is the power supply, or is that what you're reading on the multimeter from the LEDs after a hit? That seems kinda high for a receiver (photo resistor?), I think the 9v would be primarily on the emitter side.

08-05-2009, 11:02 PM
Good catch. I double checked and it is doing about 3.? on every hit (i need a meter that displays in digital :) ) however when you have been hit 10 times you loose and that leaves the lights on instead of just a blink like when hit. when you loose they stay on and the voltage is 9 volts until you turn the guns off then on again.

09-07-2009, 04:12 AM
Sounds to me like when a hit is registered, the voltage jumps to 9volts so quickly, that your meter averages it out to about 3 volts. When the game is over and you lose, the voltage stays high at 9 volts, until the game is reset.

In this case, the 9 volts and zero are the two output levels coming from the gun. If your 8/8/8 board takes a 5 volt input, then you will need to drop the voltage down by using two resistors in a voltage drop configuration. You can use two 2.2k resistors to drop the voltage by half (4.5 volts). This is high enough for the i/o to read it as a high (5volt).