: The CI-V bus uses a single bidirectional line (half-duplex) plus a ground. This line is typically terminated with a 3.5mm mono phone jack.
Here's a more detailed schematic using the FTDI FT232RL chip:
In your software (Ham Radio Deluxe, Fldigi, WSJT-X), select the assigned COM port. Baud Rate: Set to 1920019200 (default for most modern Icom) or "Auto". icom ci v usb interface schematic top
There is between the computer's ground and the radio's ground, protecting your radio's delicate microprocessor from power surges. 3. The Legacy Option: Transistor-Based CI-V Interface
Often uses two 1N4148 diodes or a transistor arrangement, separating the RX and TX of the IC into a single 3.5mm tip connection. : The CI-V bus uses a single bidirectional
: Connects to the PC; the converter chip is powered by the USB 5V line. Radio Side : Uses a 3.5mm mono phone plug . Tip : Data signal (bi-directional TTL). Sleeve : Ground reference. Icom IC7300 A to Z #27 CI-V Settings
Every major Icom HF transceiver since the has featured a CI-V port on its back panel. This persistence turned CI-V into a "lingua franca" for radio enthusiasts, allowing a single interface design to work across decades of equipment. The Schematic: Elegance in "One Wire" Baud Rate: Set to 1920019200 (default for most
Acts as an open-drain/open-collector drive, pulling the data line down to 0V when transmitting, and releasing it high (via a pull-up resistor) when idle. Pull-up Resistor: A resistor connected to