Simulates the full RS-485 half-duplex channel on the ESP32+CAN+RS485 board:
- SN65HVD1781 behavioral driver/receiver (3.3V native, 32 unit loads)
- Half-duplex direction control via DE/RE GPIO4
- 560Ω bias resistors keeping bus HIGH during idle (NMEA 0183 failsafe)
- 120Ω termination at both ends of a 10m T-line model (Zo=120, Td=50ns)
- Transmits ASCII 'G' (0x47) at 4800 bps — one complete NMEA character
- Second node as passive 12kΩ unit-load receiver
- .meas directives verify Vdiff > ±200mV (RS-485 spec) in both polarities
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
