Icom Ci V Usb Interface Schematic Top [cracked] May 2026

The Icom CI-V (Communication Interface V) USB interface is a serial communication bridge that allows a computer to control amateur radio equipment. Modern designs typically center around a USB-to-UART bridge chip, which converts USB signals into the 5V TTL (Transistor-Transistor Logic) levels required by Icom's half-duplex single-wire bus. Core Design Principles

Physical Layer: 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.

Signal Conversion: The interface must combine the separate Transmit (TX) and Receive (RX) lines from the USB chip into this single bidirectional line. This is often achieved using an open-collector (or open-drain) configuration to prevent signal contention. Primary Components:

USB Controller: Common chips include the FTDI FT232RL or Silicon Labs CP2102.

Buffering: A 7417 hex buffer or simple switching transistors (e.g., 2N3904) are frequently used to handle the open-collector drive. Popular Schematic Variations

FT232RL Direct Interface: A popular design from N5DUX uses the FT232RL chip directly, requiring minimal external components beyond a few capacitors for noise decoupling. icom ci v usb interface schematic top

Simple Transistor Circuit: For those using a basic USB-to-TTL adapter, a simple circuit using two transistors can combine the TX and RX lines into the single-wire CI-V bus.

Buffered Design: High-reliability designs often use a 7417 hex buffer IC as recommended in the ARRL Handbook to isolate the computer from the radio. Implementation Tips

Power: Most USB CI-V interfaces are powered directly from the computer's 5V USB bus, eliminating the need for an external power supply.

Cabling: Use shielded audio cable for the connection between the interface and the radio's "Remote" jack to minimize RF interference.

Drivers: Ensure the correct virtual COM port drivers (e.g., FTDI or CP210x) are installed on your PC before connecting to rig control software like Ham Radio Deluxe. ICOM CI-V - K7MEM The Icom CI-V (Communication Interface V) USB interface

Creating a USB interface for the Icom CI-V, a protocol used by Icom radios for computer communication, involves designing a simple interface that converts the CI-V's serial signal to a USB signal that a computer can understand. The CI-V protocol uses a 9-pin D-sub connector with a specific pinout and typically operates at 9600 bps.

Below is a basic overview of how to create a USB interface for Icom devices using an FTDI chip, which is a popular choice for USB to serial conversions. This example assumes you are familiar with basic electronics and soldering.

Typical CI-V USB Interface – Top View Description

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):

| 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) | USB D+ / D‑ go from J1 to

Top copper traces (conceptual):

• USB D+ / D‑ go from J1 to IC pins (CP2102 pins 4 & 5 or CH340 pins 6 & 7).
• UART TX (from IC) goes to base/gate of Q1 (inverter stage).
• Collector/drain of Q1 pulls the CI‑V data line low (open collector).
• UART RX (to IC) goes from CI‑V data line via a protection resistor (1kΩ) and optionally a second inverter stage for correct polarity.
• CI‑V data line has a 4.7kΩ pull‑up to +5V (or to radio’s Vcc via the TRS cable).
• Ground plane on bottom side (not visible from top).

4. Detailed Schematic (Top View / PCB Layout Considerations)

The term "top" could also refer to the top side of the PCB or top layer routing in an EDA tool like KiCad or Eagle. For a successful layout:

1. Split ground plane: Create two distinct ground regions – USB_GND and RADIO_GND. Connect them only through the optocouplers and maybe a 10Ω resistor + 0.1µF capacitor for HF noise bypass.
2. Keep traces short between optocoupler outputs and the CI-V connector to prevent parasitic ringing.
3. Add ferrite beads on USB VBUS and GND to limit RF entry.
4. Include a 100mA PTC fuse on USB power.

Example configuration for common radios

• Baud: often 19200 or 1200 bps depending on model — set adapter to match radio.
• Logic: active-low open-collector style; use open-drain friendly interface.

Option 3: The "CI-V Addressing" Circuit (Isolated)

Best for: High-end base stations where you want to daisy-chain multiple radios.

If you look at the official Icom schematic (often found in the service manuals for the CT-17), they include a 74LS05 or 74HC05 Hex Inverter chip.

• This chip has "Open Collector" outputs built-in.
• You would feed the TTL TX signal into the Inverter input, and the Inverter output goes to the radio.
• This provides a very clean, robust drive that handles multiple radios on one line better than a single transistor.