Icom Ci V Usb Interface Schematic Top May 2026

Below is a textual representation of the top-level schematic for a proven CI-V USB interface. Component values are typical for 9600–19200 baud operation (some radios support 38400 or 19200 baud; adjust accordingly).

Board size: ~40×20 mm (e.g., similar to a CP2102 breakout)

Top side components (from left to right assuming USB connector on left edge): icom ci v usb interface schematic top

| Region | Component | Label / Value | |--------|-----------|----------------| | Left edge | USB mini‑B or USB‑C | J1 (USB input) | | Next | USB‑to‑UART IC | CP2102 (QFN‑28) or CH340G (SOP‑16) | | Next | 3.3V regulator (if needed) | AMS1117‑3.3 (SOT‑223) | | Center‑right | Dual transistor / inverter | 2N7002 (x2) or BC547 (x2) or IC like 74HC05 (open‑drain) | | Right edge | 3‑pin header | J2: Tip (DATA), Ring (GND), Sleeve (optional +5V) → to 3.5mm TRS jack (Icom CI‑V plug) |

Top copper traces (conceptual):

-------------------------------------
| USB-B socket       |  CI-V jack   |
|                    |   (top edge) |
|  FT232RL   IC2(6N137)  Q1(2N3904) |
|           |                       |
|  IC3(6N137)  78L05(optional)      |
|------------------------------------

The Icom CI-V system is a serial communication protocol used to control Icom radios. It uses a simple two-wire interface (Data and Ground) that operates at TTL logic levels (5V).

Modern computers no longer have serial ports (RS-232), and CI-V is not directly compatible with USB. Therefore, an interface is required to bridge the gap. The schematic design depends entirely on which USB chip you choose to use. Below is a textual representation of the top-level

Here are the three most common schematic topologies, ranging from the easiest to build to the most traditional.

Data from CI-V bus to PC RXD.

  • Output side (PC):

    • 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.

           +---------------------+
       |   USB Connector     |
       +----------+----------+
                  |
       +----------v----------+
       |  USB-to-Serial IC   |
       |  (FT232RL / CH340)  |
       |  - TTL Out (TxD)    |---(0/3.3V)---+
       |  - TTL In (RxD)     |<--(0/3.3V)---+
       +----------+----------+              |
                  |                         |
       +----------v----------+              |
       |  Logic Inverter     |              |
       |  (Transistor/NAND)  |              |
       +----------+----------+              |
                  |                         |
       +----------v----------+              |
       |  Bidirectional      |              |
       |  Buffer / Open-     |              |
       |  Collector Driver   |<-------------+
       +----------+----------+
                  |
       +----------v----------+
       |  CI-V Connector     |
       |  (3.5mm stereo or   |
       |  2-pin phoenix)     |
       +---------------------+