On the isolated PC side, the phototransistor conducts, pulling the USB chip’s RXD pin low. A 10kΩ pull-up resistor connected to the USB's 5V line keeps RXD high when the bus is idle. 3. Combining TX and RX into a Single Wire
. These chips convert USB data into standard asynchronous serial signals.
If you are looking for ready-made, reliable interface solutions, you can explore commercial options like the ones reviewed on YouTube . If you'd like, I can provide: A for the FTDI-based schematic PCB layout design tips Specific software configuration steps for HRD or FLDigi Let me know how you'd like to proceed with your project! Share public link icom ci v usb interface schematic top
If you are searching for "icom ci v usb interface schematic top", you are probably looking for a clear diagram of a that includes the correct bus driver, not just a UART‑to‑CI‑V connection sketch. The G3VGR design—or a modern variation using a CP210x board with an external 7417—is an excellent starting point.
Add a from the combined line to VCC (5V) to ensure the signal stays high when idle. On the isolated PC side, the phototransistor conducts,
) TTL signal. This signal is fed into a simple single-transistor inverter (or a dual-diode steering circuit) to combine TX/RX into the single CI-V wire.
: Many builders use a small plastic project box or even a "Manhattan style" construction on a piece of unetched PCB board for a solid ground plane. www.ka6wke.net 4. Software Setup Explore USB with this USB to CI-V Interface - N5DUX Combining TX and RX into a Single Wire
FT232RL or similar, converting USB to RX/TX lines.
Below is a functional block diagram of the classic, proven “top-level” CI-V USB interface. Hundreds of online projects and commercial products (like the CT-17 or U5 Linker) follow this design.
The Icom Communication Interface-V (CI-V) is a robust, single-wire, TTL-level serial protocol used across decades of Icom transceivers for computer control (CAT - Computer Aided Transceiver). While older computers had native RS-232 serial ports, modern computers require a USB-to-CI-V interface.
CAT (Computer Aided Transceiver) is a generic term for computer control of a radio. CI‑V is Icom's specific implementation of a CAT system. Other manufacturers (Yaesu, Kenwood, etc.) use their own protocols, although many modern radios from all brands have similar physical‑layer characteristics.