Bandswitch Transmit Lockout


Sometimes computer control makes things TOO easy.  With my automated station running 7 instances of PowerSDR controlling 7 different radios and with bandswitching occurring automatically when I switch from one GUI to the next, it is too easy to switch bands while transmitting, or to start transmitting as one is switching bands, when one is in the midst of a busy contest.  In order to prevent bandswitching while transmitting or initiation of the transmit sequence while bandswitching is occurring, I made a Bandswitch-Transmit Lockout device that prevents such hot-switching. 

Once again, I used a Parallax Propeller.  I used PS2504-5 optoisolators on both input and output.  Rather than use the PTT inputs from the footswitches for the PTT controls for this project, I used the PTT outputs from each of the 7 radios.  I made this choice so that the lockout would be effective even if I actuated the transmit cycle 'in software' from one of the PowerSDR GUIs.   The device is capable of handling up to 8 separate PTT inputs [all 'ground to activate PTT'] and Pins 2,7,8,9, and 15 from the computer's LPT port [these control bandswitching].  Outputs are up to 8 PTT outputs which go to sequencers for each band, and Bandswitching signals that correspond to pins 2,7,8,9, and 15 from the computer's LPT port that go to the N3FTI bandswitch except under appropriate 'lockout' conditions.

The device consists of the Propeller Proto Board USB and two custom boards that I had made at  ExpressPCB using their MiniBoard service.  One board receives and controls the PTT signals [PTT Control Board], and the other board receives and controls the LPT Bandswitch signals [Bandswitch Control Board].  Bmp schematic and ExpressPCB .sch and .pcb files for the PTT Control Board are here.  Bmp schematic and ExpressPCB .sch and .pcb files for the Bandswitch Control Board are here. 

The code is listed in this hyperlink.  The .spin file is here

The code is compiled using the free Propeller Tool software by Parallax.

Copyright 1997-2010 COPYRIGHT Roger Rehr W3SZ. All Rights Reserved

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