When the computer transmits a logic "High" (5V), the diode blocks the current, and the 4.7k resistor pulls the CI-V bus high. When the computer transmits a logic "Low" (0V), the diode conducts, pulling the CI-V bus down to 0V. When the radio transmits, the computer’s TXD line rests at a logic "High", allowing the radio to freely pull the RXD line up and down. 3. RFI Protection (Crucial for Transmitting)
+----------------+ +----------------+ +-------+ +---------------+ | | | | | | | | | USB Port +------+ USB-to-TTL +------+ CI-V +------+ Icom Radio | | (PC) | | Serial Adapter| | Level | | (CI-V Port) | | | | (e.g., FT232R)| | Shift | | | +----------------+ +-------+--------+ +---+---+ +-------+-------+ | | | | | | | +5V, GND, TX, RX | Data, GND | Data, GND | (TTL Levels) | | | | | +-----------------------+ | | v (Shared CI-V Bus) icom ci v usb interface schematic top
pull-up resistor (R4) between Pin 8 (VCC_RIG) and Pin 6 of . When the computer transmits a logic "High" (5V),
Do you prefer using or an off-the-shelf breakout board ? +5V (from USB) | \ / R1 (4
+5V (from USB) | \ / R1 (4.7kΩ) -> Pull-up resistor \ / | | +-----------------------o To CI-V Bus (Data Line) | | | | | (D) | +---|<|----o | | D1 (1N4148) | | | | | | | | | R2 (1kΩ) | | +-------/\/\/\----------o o-----+ | | | | | | | (B) | (E) | +----------------------||---------+ | \\| Q1 (2N3904/NPN) | | (BJT) | | | | (TX from FTDI)------o o---+ | | | | | | (RX to FTDI) | | | | | | | | | (C) | | +---/\/\/\--------------o o------+ R3 (1kΩ) | | GND