1968neil
Senior Member
Hi Folks,
Just got this project working and well tested.
The idea was to use two redundant ICOM ICF12 PMR VHF handheld's as a talkthru repeater for gate entry systems that can be disabled by selcall (5 Tone Signalling). ie: start up then shutdown).
The rx/tx status led also blinks red constantly when a valid 5 tone is received This activates the transmit radio and in turn passes the received audio thru to the transmitting radio, this can be deactivated when a shutdown 5 tone is received.
As i didnt have a constant logic high i needed to use the flashing of the led to trigger my output but also when the led stopped flashing have a bit of delay (hang time) before it dropped out.
Counting the pulse of the led was my best option, but how ?
Using an interupt as sugested by hippy i was able to wait in a loop until the pulse appeared then the interupt would take over until the pulse dissapears. then re-enables the interupt and the whole thing starts again.
I've attached a circuit and PCB layout for those interested. All of which are tried tested and in daily operation.
Enjoy
Regards
Neil
Just got this project working and well tested.
The idea was to use two redundant ICOM ICF12 PMR VHF handheld's as a talkthru repeater for gate entry systems that can be disabled by selcall (5 Tone Signalling). ie: start up then shutdown).
The rx/tx status led also blinks red constantly when a valid 5 tone is received This activates the transmit radio and in turn passes the received audio thru to the transmitting radio, this can be deactivated when a shutdown 5 tone is received.
As i didnt have a constant logic high i needed to use the flashing of the led to trigger my output but also when the led stopped flashing have a bit of delay (hang time) before it dropped out.
Counting the pulse of the led was my best option, but how ?
Using an interupt as sugested by hippy i was able to wait in a loop until the pulse appeared then the interupt would take over until the pulse dissapears. then re-enables the interupt and the whole thing starts again.
I've attached a circuit and PCB layout for those interested. All of which are tried tested and in daily operation.
Enjoy
Regards
Neil
Last edited: