From F4JND's log: a rig sitting on 145.550 MHz FM produced status lines reading
16445550000, 8364550000, 5817408364 and 12640 Hz between good readings — the last
of those even resolved to a 6 cm band.
BCDToFreq treated the nibbles 0x0A..0x0F as the digits 10..15, so a byte stream
that had lost frame sync still decoded into a number. The same log shows why sync
was lost: PTT round trips timing out and a scope stream the rig kept rejecting
(0x27), both competing with the poll on one serial line.
Non-decimal nibbles are now refused. Each caller keeps its last good value rather
than publishing noise: the frequency reader returns an error, the sub-VFO reader
returns not-ok, and the scope keeps its previous edges. Garbage that LOOKS like a
frequency is worse than a refused frame — it reaches the display, the band slots
and eventually the log, and it is the operator who then has to disprove it.
The test builds its fixture with FreqToBCD rather than by hand, because my
hand-written one was byte-reversed and the test caught it.
This does NOT explain the white screen that was also reported, and I have not
claimed it does: it removes one source of absurd values reaching the UI, which is
worth doing on its own evidence.
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