[hpsdr] Common Hermes firmware for Anan/Alex/Apollo?

["Per Øyvind Jonsson"]

First, thank you to the gurus for the fantastic effort with hardware, firmware and software!

There is however one Hermes issue which begs to be solved, both to reduce user confusion, and hopefully also the effort needed to update the firmware. Today we need two Hermes FW versions. My understanding is that this is because the ANAN-10 and ALEX filters have different cut-off frequencies. It would of course be nice if Hermes could auto-detect which filter board is connected, but based on the schematics I have seen this will require some hardware modifications. Possible, but not desirable.

When setting up PowerSDR we already need to specify the radio model, and some of this information is sent to Hermes. Would it be possible to extend this to also send information on which filter board is used? This could allow the FW to set the proper filter parameters. According to the USB_protocol_V1.58 there does not seem to be any bits that could be used directly, but it may be possible to use some otherwise unused combinations. One possibility seems to be to use C2 in the sequence starting with C0 = 0001001x, like this:

bit 7: VNA mode (no change)
bit 6: Alex manual (no change)
bit 5: Hermes filter board (0 = Alex or ANAN, 1 = Apollo)
bit 4-3-2: If bit 5 = 1 sets Apollo options (no change)
 If bit 5 = 0 could be used to specify which board(s) like so:
 000 - None
 001 - Alex RX
 010 - Alex TX
 011 - Alex RX+TX
 100 - ANAN-10
 other combinations available for future boards?
bit 1: Metis/Penelope etc Mic/Line In (no change)
bit 0: Hermes etc Mic Boost (no change)

Thoughts/comments?

LA9WX
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