progress report mar 9 .
the code is ready for testing. and was loaded into a 12F508. a no-scope approach is being worked.
and once the fire-signal-out looks good the scope will be attached. as only with the scope can the actual
delays following the -71 signal be verified.
experimenting with a single pulse to the -71 pin yields a single pulse on the fire pin. or it did once. and now it wont repeat.
a single fire out pulse is expected as t_dly is preloaded prior to a -71 signal being detected. this should result in a t_dly followed by the fire pulse.
then the code is suppose to loop at the GP3 pin until the -9 signal comes along.
looping there means the single -71 pulse will result in a fire pulse on GP2 only once
in order to get this to happen though the pulser and logic probe are already connected to the uC when they all have +5 power applied. doing this step
allows transients from those 2 devices to interact with the uC pins.
and these transients could be what is causing the GP2 pin to fire
adding pull-down resistors did not remedy this matter. one idea to try is edit the
code so that pin 4 /MCLR ( the -9 input pin GP3 ) is enabled.
this will allow the uC to be reset with a switch instead of having to cycle the +5 V supply. thus there should be no pulser & probe transients on the input pins. this is what will be tried first. enabling the MCLR pin function.
and re-coding so GP4 is the -9 input pin , not GP3
oh , one thing learned along the way ... using the logic probe on all 6 i/o pins revealed that
only 4 of them would indicate a logic 0 ( the default ). at first i thot something was wrong with
this uC. then realized the 2 pins not showing a logic 0 were setup as inputs. so , of course,
they would not signal a logic level.
the code is ready for testing. and was loaded into a 12F508. a no-scope approach is being worked.
and once the fire-signal-out looks good the scope will be attached. as only with the scope can the actual
delays following the -71 signal be verified.
experimenting with a single pulse to the -71 pin yields a single pulse on the fire pin. or it did once. and now it wont repeat.
a single fire out pulse is expected as t_dly is preloaded prior to a -71 signal being detected. this should result in a t_dly followed by the fire pulse.
then the code is suppose to loop at the GP3 pin until the -9 signal comes along.
looping there means the single -71 pulse will result in a fire pulse on GP2 only once
in order to get this to happen though the pulser and logic probe are already connected to the uC when they all have +5 power applied. doing this step
allows transients from those 2 devices to interact with the uC pins.
and these transients could be what is causing the GP2 pin to fire
adding pull-down resistors did not remedy this matter. one idea to try is edit the
code so that pin 4 /MCLR ( the -9 input pin GP3 ) is enabled.
this will allow the uC to be reset with a switch instead of having to cycle the +5 V supply. thus there should be no pulser & probe transients on the input pins. this is what will be tried first. enabling the MCLR pin function.
and re-coding so GP4 is the -9 input pin , not GP3
oh , one thing learned along the way ... using the logic probe on all 6 i/o pins revealed that
only 4 of them would indicate a logic 0 ( the default ). at first i thot something was wrong with
this uC. then realized the 2 pins not showing a logic 0 were setup as inputs. so , of course,
they would not signal a logic level.
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