I’m looking for a very simple pulse counter that will give me a digital high when pulsing and a low when no pulsing. I looked at the pulse counter but not sure if that would give me what I’m looking for. I’d like to attach a low resolution encoder to give pulses when a string is pulled across it. When there is motion I need to turn on another device, when there is no motion I need to stop.
I’m a little confused as to whether you are actually ‘Counting’ pulses or just trying to detect if a pulse train stops sending pulses. If you just wish to detect a lack of pulses I would suggest that it could be achieved using a simple timer and use the detection of a pulse reset the timer. If no pulses are detected the timer would simply time out and call your alarm method.
It seems like you don’t actually have a need for a pulse counter at all, you just need a way of detecting presence or not of a string. I would think if you can explain that part of your need first, so we can help give you a better solution.
My initial thought is you may just need some kind of beam breaker that generates a digital output.
How fast do you expect the pulses to be?
A little more clarification on this process. (A detection of the string only will not work - I need a way to determine if it is moving or not.)
I have a machine that is wrapping 16 individual strings around a post. When the wraps are finished wrapping we cut and remove it and then start the process again. If the the machine misses one of the 16 ends of the string then that string is not moving until the operator notices it and stops the process to get it back into the wrap. I’d like to detect the non-moving string and stop the process.
As far as speed the string is moving about 34 inches a second so depending on the resolution of the encoder it would determine the pulses per second.
So then you need a tachometer on each wire to determine if they are moving? If you broke up an optical mouse and passed the wire across the sensor, then the mouse will transmit the rate of the wire change to the host machine/µC. But since you are using 16 wires, then you will need 16 of them. I suppose you could use a USB Hub to connect them all to the same NETMF device, but I don’t think that the firmware is there to distinguish one mouse from another.
Another route is to use the pules from the encoder to rapidly discharge a charging capacitor. If the pulse train doesn’t happen quickly enough the cap will charge to the switch on voltage of a switch (like a power transistor) turning on your equipment. Sometimes the solution can be analogue.