Generate band switching control signals for frequency-hopping

[loschwa]

Dear Lee,
it would be extremely useful if the RaspberryPi would in addition to the frequency generation on GPIO4 also provide a control signal on some of the other GPIOs for the selection of an appropriate low-pass filter. With that feature it would be possible to use WsprryPi on multiple frequencies without manually switching the low-pass filters. For instance it would be possible to control the 'Ultimate relay-switched LPF kit' of QRP-Labs. This kit allows to select one of 5 different low-pass filters and it requires a logical '1' on either one of its 5 inputs.

This could work such that the first 5 frequency 'slots' in the frequency configuration string ( e.g. '80m 40m 30m 20m 15m') would be associated with GPIOs 17, 27, 22, 23, 24. When WsprryPi starts transmitting on 80m the GPIO17 outputs a '1' which would allow the selection of the 80m-low-pass filter. When the transmission stops the GPIO17-output reverts to '0'. When the transmission window opens for 40m, GPIO27 outputs a '1' ... and so on.

Please let me know if I could help to implement the new function. However, I don't have a profound knowledge of C-programming but I could help with the documentation.

73s, Lothar (DK9FQ)