This article provides a complete, top-to-bottom analysis of the CI-V USB interface—its schematic topology, component selection, PCB layout considerations, and practical build notes.
A high-speed digital isolator that isolates the TX and RX lines cleanly up to 150 Mbps. icom ci v usb interface schematic top
Now, with your schematic in hand and this guide by your side, you are ready to build a CI‑V USB interface that not only works but works correctly—and that is something that no "complete" schematic can ever replace. This article provides a complete, top-to-bottom analysis of
The collector of this phototransistor is wired directly to the CI-V Tip line. The emitter connects to the Radio Ground (Sleeve). The collector of this phototransistor is wired directly
PC SIDE (USB Powered) RADIO SIDE (Radio Powered) --------------------- ------------------------- TXD ---> [ 6N137 Opto 1 ] --------> Combined CI-V Bus (Tip) RXD <--- [ 6N137 Opto 2 ] <-------- Combined CI-V Bus (Tip) GND_USB GND_RADIO (Sleeve) Use code with caution. 3. The CI-V Combining Network (The "Top" Schematic Logic)
USB‑UART IC (CP2102) TX pin ──┬─ 10k resistor to 3.3V └─ gate of 2N7002 (Q1) RX pin ──────────┬─ 1k resistor ── drain of Q1 ──┬─ to CI‑V data line └─ (optional 2nd transistor for correct idle polarity)
The radio transmits status data or frequency updates back to the PC over the same Tip wire.