Xiegu speaks CI-V with a reduced command set: frames, BCD encoding, addressing
and the opcodes for frequency, mode, PTT and split are Icom's, so this reuses
internal/cat/civ wholesale instead of re-deriving a codec.
It is a SEPARATE backend rather than the Icom one at address 0x70, because what
the two rigs do NOT share is the deciding part. The Icom backend reads the
spectrum scope, the DSP block, data mode via 1A 06 and the model id via 19 —
none of which a Xiegu implements. Pointed at a G90 it would poll every cycle for
answers that never come, and spend its silence tolerance on commands the radio
was never going to support.
Two consequences of the rig's smaller mode table are handled explicitly rather
than left to fail: there is no data mode, so a digital QSO is set to plain
sideband (what the operator does on the radio anyway) instead of being refused;
and the split TX frequency is NOT reported, because reading the unselected VFO
needs 0x25, which the Xiegu table does not list — a split flag carrying a wrong
TX frequency is worse than the flag alone, since the frequency is what gets
logged.
The published command table has rows that slipped during typesetting (0x07 and
0x0F share a block). Where it contradicts itself the Icom meaning is used, the
rest of the table matching Icom exactly, and every unexpected reply is logged
raw so a first on-air run settles it.
NOT yet verified on a radio.
rouggy
e2aba828a9