Thank you for reading my posting,
I have been working with a simple circuit involving a PIC12F617 microcontroller written in assembly. This circuit simply blinks an LED on for 1 sec and then off for 1 second and then repeats in an endless loop.
I have then taken this circuit and powered it on my distributor testing machine through a distributors 12v(14.3v) and ground.
When the power is on with NO spinning of the distributor the circuit blinks as it should, 1 sec on and 1 sec off. I then increase the rpm and see how the circuit reacts to noise.
What I found:
1) At '0' rpm the circuit works perfectly.
2) At a static rpm the circuit sometimes works for about 30-40 seconds then blinks sporadically and then just stops working at which time I return the rpm to '0' and disconnect either the ground or power and reconnect. The circuit will then blink as it should at '0' rpm.
3) I do not have BOR or POR active in my program. I did try BOR active but did not see any change.
4) I replaced the 5.1v zener on the VDD for the PIC with a 12v zener and found the circuit functioned better. This goes against my logic on this as I thought a 5.1v zener would work better for this.
Questions:
1) How can I better deal with the noise in this circuit?
2) Should I have different values for my zener diodes and/ or capacitors?
3) Is there a better way to make this circuit immune to noise?
I am using the 12v and 5.1v zener in series for a 17v total because those were the only values I had on hand.
The vertical line to the right of the PIC 12F617 is not a trace it is a line that appeared when document was copied, please ignore it.
This is working out to be a good exercise in solving issues with noise in a microcontroller circuit.
Thank you for your incite.
Peaches
I have been working with a simple circuit involving a PIC12F617 microcontroller written in assembly. This circuit simply blinks an LED on for 1 sec and then off for 1 second and then repeats in an endless loop.
I have then taken this circuit and powered it on my distributor testing machine through a distributors 12v(14.3v) and ground.
When the power is on with NO spinning of the distributor the circuit blinks as it should, 1 sec on and 1 sec off. I then increase the rpm and see how the circuit reacts to noise.
What I found:
1) At '0' rpm the circuit works perfectly.
2) At a static rpm the circuit sometimes works for about 30-40 seconds then blinks sporadically and then just stops working at which time I return the rpm to '0' and disconnect either the ground or power and reconnect. The circuit will then blink as it should at '0' rpm.
3) I do not have BOR or POR active in my program. I did try BOR active but did not see any change.
4) I replaced the 5.1v zener on the VDD for the PIC with a 12v zener and found the circuit functioned better. This goes against my logic on this as I thought a 5.1v zener would work better for this.
Questions:
1) How can I better deal with the noise in this circuit?
2) Should I have different values for my zener diodes and/ or capacitors?
3) Is there a better way to make this circuit immune to noise?
I am using the 12v and 5.1v zener in series for a 17v total because those were the only values I had on hand.
The vertical line to the right of the PIC 12F617 is not a trace it is a line that appeared when document was copied, please ignore it.
This is working out to be a good exercise in solving issues with noise in a microcontroller circuit.
Thank you for your incite.
Peaches