Major correction: All firmware versions use GPIO bit-banging for DiSEqC,
NOT I2C-based control as previously reported. Deep decompilation of the
sub-functions (byte transmit, bit symbol, tone burst) across v2.06, Rev.2,
and v2.13 reveals identical Manchester encoding algorithms with only the
data GPIO pin changed per PCB revision:
- v2.06: P0.7, Rev.2: P0.4, v2.13: P0.0
- P0.3 (22kHz carrier gate) unchanged across all versions
New section 7: Complete DiSEqC timing chain analysis including:
- Timer2 configuration (RCAP2=0xF82F, 4MHz clock, 500us tick)
- Manchester encoding waveforms (3 ticks/bit, 1.5ms/bit, 667 baud)
- Byte transmission (8 data + odd parity = 13.5ms)
- Tone burst timing (25 ticks = 12.5ms)
- CPU clock compensation in delay function
- External 22kHz oscillator architecture
