Hi everyone my first post so please be gentle.
I have a system that generates an event from a trigger the trigger is the closing of a small switch.
The problem is the switch/sensor only closes for a short period of time. The electronics that detect the pulse detect it as part of existing device (the device has GPIO available). Which are used "sense" the event switch closing.
The issue is that the detection of the closure is unreliable, we believe that this unreliability comes from the "sampling of the GPIO" which occurs at about 120hz (this is done by software) the software was modified to to sample at 1Khz (polling the GPIO at 1khz) but we think the GPIO are locked in firmware of the device to 120Hz detection (does this make sense?)
The process does work but isnt reliable enough (worked 3 time out of 3 then 1 out of 4) What i need to do is extend the output of the switch pulse at the moment the time the switch is closed for is short <10ms if we can modify the output to be closer to 100ms then the "sense will be more reliable"
My first thought was an SR flip flop which will work or a 555 based timer or any sort of latching circuit. the issue is the size of the solution.
If possible we want to avoid any IC components and keep the components down to 2 or 3 legged items.
One idea is to use a small capacitor that is charged by the switch closing but discharges slowly through a resistor? but struggling with the design can anyone help?
Some information about the system:
Power is 12V DC
Sensor is a mechanical switch NO (push to make)
Devices has opto isolated inputs available
Current system has 12V->switch->Device input
Challenge for the analogue experts out there can this be done with maximum 3 additional components? Was thinking Capacitor and Diode in series where capacitor charges quickly when switch closed but discharges slowly when switch returns to open?
Thank you for taking the time to read this and I appreciate any advice offered. Many thanks.
I have a system that generates an event from a trigger the trigger is the closing of a small switch.
The problem is the switch/sensor only closes for a short period of time. The electronics that detect the pulse detect it as part of existing device (the device has GPIO available). Which are used "sense" the event switch closing.
The issue is that the detection of the closure is unreliable, we believe that this unreliability comes from the "sampling of the GPIO" which occurs at about 120hz (this is done by software) the software was modified to to sample at 1Khz (polling the GPIO at 1khz) but we think the GPIO are locked in firmware of the device to 120Hz detection (does this make sense?)
The process does work but isnt reliable enough (worked 3 time out of 3 then 1 out of 4) What i need to do is extend the output of the switch pulse at the moment the time the switch is closed for is short <10ms if we can modify the output to be closer to 100ms then the "sense will be more reliable"
My first thought was an SR flip flop which will work or a 555 based timer or any sort of latching circuit. the issue is the size of the solution.
If possible we want to avoid any IC components and keep the components down to 2 or 3 legged items.
One idea is to use a small capacitor that is charged by the switch closing but discharges slowly through a resistor? but struggling with the design can anyone help?
Some information about the system:
Power is 12V DC
Sensor is a mechanical switch NO (push to make)
Devices has opto isolated inputs available
Current system has 12V->switch->Device input
Challenge for the analogue experts out there can this be done with maximum 3 additional components? Was thinking Capacitor and Diode in series where capacitor charges quickly when switch closed but discharges slowly when switch returns to open?
Thank you for taking the time to read this and I appreciate any advice offered. Many thanks.