New Gear Tooth Sensor- Connection

My team has decided to use the gear tooth sensors this year. We installed the new ones into the transmission plates, but I don’t know where to plug in the PWM. There are two sets of holes marked like a PWM (Black, Red, and White) Are these where we plug in the PWMs? If so which set, or do we use both? And if not how do we connect the sensors to the Robot Controller?

Thanks in advance for the help.

Start by reading this document. http://www2.usfirst.org/2006comp/other/2006_Sensor_Basic_Operation.pdf

plz post what you come up with

I always thought the gera tooth sensors plugged into the digital input? Something about using interrupts to get the microchip to acknowledge all the things the sensor is sending since a pulse is onli like…80 microseconds or something…mayb it was milliseconds not sure.

You want to run them into one of the first 6 digital IO ports, so that you can use them as interrupts. Search for some posts by Kevin Watson and Brad Miller about the timing issues with trying to determine direction.

You will likely want to install two 3 posistion 0.100" headers (female if you are going to use standard IFI PWM cables, male is likely better if you are making your own cables, as it will likely create a more reliable connection) onto the boards, or you can also solder wires directly to them. You will need to modify a pwm cable to feed the 12V signal to it, which I believe by the rules will have to come off its own 20A circuit breaker and be considered a “custom circuit”. Please correct me if I am wrong.

My main problem is the connection directly onto the gear tooth sensor. We have had very little work with modifying PWM cables. For the electronics we rely heavily on the supplied information. Can anyone walk me through the connection process?

You can use solder if you have a very steady hand and a small iron, but I don’t know if that might cause problems with the sensor itself. A little bit of hot glue or epoxy should do the trick :smiley:

The circuit boards are designed to be soldered onto, and it shouldn’t be too hard. Do not use any sort of glue or adhesive to make the electrical connection, as most glues will not conduct electricity well and any connection you do manage to make will be unreliable. You can use hot glue to cover your solder connection to provide strain relief and protection from shorting out, but if you don’t have a strong solder joint underneith, your connection will fail.

To make the signal connection, cut a PWM cable in half, and strip a small amount from the ends of the three wires, apply a small amount of solder to the exposed ends, fit them into the appropriate holes, and apply more solder to attach them in place. The wires will connect to the holes that say:
G 5 S
B R W
with B being Black, R being Red, and W being White.

You will also need to supply 12 volts to the board where it is labeled:
G 12
B R W
Solder a thin black wire to the hole labeled B and connect the other end to ground, and then solder a thin white or red wire to the hole labeled W and connect the other end to power through your circuit breaker panel.

I won’t go into the details of how to solder here, since it’s been covered many times on the board (try searching, or use Google), but just make sure you have a clean hot iron, and that you apply heat to the wires or solder pads, not the solder itself, when making the final connection.

EDIT: Can this thread be moved to the Electrical section?

We tested one of our sensors, and all we needed was the first pwm cable and a single wire from 12 to a 20 amp “custom circuit” breaker. The pwm was plugged into a digital input. (the other ground is redundant according to my meter at the circuit board) The doc is correct about the pulse width. If there is interest I can pull a pic of each width from my tek scope. We had clean response at 5350rpm (891 Hz) on a 10 tooth #35 chain sprocket. The scope was connected to main ground and the signal header on the robot controller.

Thanks a lot for the help, it was exactly what I needed.

so to wire this sensor on the board you just wire 2 pwm cables to them according to the markings on the board?

has anyone had problems determining direction?

our code uses the interrupts on digital in 01/02 and two timers at 60us. when an interrupt occurs, it waits 60us then the timer interrupt makes it check the pin again. if the pin’s still on then it’s spinning one way, if it’s not, then it’s the other.

except the counter goes berserk.
does anyone have the same problems? +is this how anybody else is doing it?
[it might be that we’re not disabling the timer like i swore i did… im gonna check that now =P]

Do you need to hook these up to a Spike?

Our team is using two hall effect sensors, on the two gears for our main drive.

I looked at this thread yesterday, and hooked up the sensors as described, with power plugged into the main board on a 20 amp breaker (two sensors on one breaker). The sensor outputs were hooked into the digital inputs, and we were getting readings from the sensors just fine (save for a code problem we are working on). I left the redundant ground from the power PWM cable disconnected.

There was some discussion at this morning’s meeting about whether or not to power the Hall Effect Sensors through a Spike (this would involve some coding to make sure the Spike is either always on, or only on when taking a reading). I couldn’t see why you’d need one, but the discussion was left unresolved as of when I went home.

Also, does each sensor need to be on a seperate 20 amp circuit? I put them both on one just because we were trying to get it running quickly so that we could test code. I doubt those little sensors will ever draw 20 amps, personally.