Hobcat - TrxAVR MOX control     (manual receive/transmit switching)

A MOX button has been added to Hobcat's DDS window (added Hobcat 1.055 /TrxAVR version 1.43)

This is a toggling button which controls the ATmega2560's PORT L bit 3 (PL3).
The system drives PL3 high for transmit. The intention is for PL3 to drive an NPN transistor which drives a
relay to ground the DSP unit's PTT input. This transistor is provided as Q4 on TrxAVRB.

 
The MOX button shows green on receieve and red and transmit.

The buttons colour (red/green) and it's behavious on clicking are determined by the DSP T/R status.
Picastar DSP is continually sending out 9600 baud 24 byte telemetry packets. These update a corresponding
24 byte data block in TrxAVR. (static uint8_t TelemBuf[24] in taStarDSP.c ). This data block is
is used for the DSP monitor display. ( Transmit is bit 7 of byte Telembuf[4]. )

When you click the MOX button, Hobcat sends out a USB request to read Telembuf from TrxAVR in order
to determine the transceiver's current T/R status,

• If the transceiver is on receive, Hobcat changes the MOX button to red and sends a USB command to
  drive PL3 high - which switches to transmit.
• It the transceiver is on transmit, Hobcat changes the MOX button to green and sends a USB command to
  drive PL3 low - which switches to receive.

TrxAVR-Picastar has a MOX timeout counter. This is set to zero every time MOX switches to transmit.
The counter applies a tranmsit time limit after which the MOX system, reverts automatically to receive.

The MOX timeout interval is set in TrxAVR-Picastar's Main Menu (5 - 600 seconds)
The interval is stored in TrxAVR EEMEM and saved/loaded by data transfer to/from trxavreemem.ini.

MOX does not work with HRD (Ham Radio Deluxe)
HRD connects to TrxAVR with the TS2000 command set.
HRD's transmit button has the usual TS2000 GET and SET functions.
GET works ok - so the button changes on transmit.
SET doesn't seem to perform its intended action .. so I cant make the button implement MOX.
(I think that this is a problem internal to HRD over which I have no control.)