icom ci v usb interface schematic top

Icom Ci V Usb Interface Schematic Top May 2026

(Computer Interface V) system is a bi-directional, single-wire serial bus used to control Icom amateur radio transceivers. While modern rigs like the Icom IC-7300

have built-in USB ports for this purpose, older or more basic models require an external interface to convert standard computer signals (USB or RS-232) to the specific (0-5V) logic used by the radio's "Remote" jack. Core Schematic Components

A DIY USB to CI-V interface typically consists of three main stages: USB-to-Serial Conversion : Modern designs use a dedicated chip like the FTDI FT232RL

to convert USB signals into standard asynchronous serial UART signals (TX and RX). Level Shifting/Interface Logic

: Because the CI-V bus is a single wire, the separate TX and RX lines from the USB chip must be merged. The "Diode Trick"

: The simplest schematic involves connecting the RX line directly to the CI-V data line and connecting the TX line to the same data line through a small signal diode (like a ). This prevents the TX line from "fighting" the RX line. Buffer ICs : More robust designs use a buffer like the 7417 Hex Buffer

(for RS-232 versions) to isolate the computer from the radio and provide cleaner logic levels. Physical Connection : The output of the circuit connects to a 3.5mm mono phone plug : CI-V Data line. : Ground (GND). How the Bus Operates Icom IC7300 A to Z #27 CI-V Settings

Building a USB to Icom CI-V interface is a popular homebrew project that allows you to control your transceiver via a computer. The core requirement is a bridge that converts bi-directional, single-wire TTL signaling ) used by the Icom CI-V protocol Top Interface Design Options USB-to-UART Module Method (Easiest)

The most modern and simple approach uses a pre-built USB-to-UART module (such as the ) and a few discrete components. Core Components: USB-to-UART module, 1N4148 diode, and a Schematic Logic: The module’s cap T cap X cap R cap X

lines are bridged to create the single-wire CI-V bus. A diode is placed between the cap T cap X

and the bus to allow the radio to pull the line low without damaging the module's transmit pin. Physical Connection:

A 3.5mm mono plug connects to the radio's "REMOTE" jack; the tip is data, and the sleeve is ground. Transistor-Based Level Shifter

For those who prefer discrete builds, a simple two-transistor circuit can shift RS-232 levels (if using a serial-to-USB cable) or module levels to the CI-V bus.

This design is often small enough to fit inside a DB-9 connector shell. It typically relies on a pull-up resistor (around ) to hold the bus high when idle. MAX232 Level Converter If starting from a standard RS-232 serial port, a

is used to handle the voltage translation between +/-12V (RS-232) and 0-5V (TTL).

Pins 11 and 12 of the MAX232 are tied together to form the bi-directional CI-V data line.

These circuits can be "port-powered" using the RTS or DTR lines, or powered externally with a 5V regulator like the Critical Specs for Your Build Signaling: 1-wire bidirectional TTL ( ); data line is when idle. Baud Rate:

Usually auto-sensing, but commonly set to 9600 or 19200 bps in software. Uses Hexadecimal framing starting with "FE FE" (Attention). CI-V Communications Interface-V, Reference Manual 3.2 icom ci v usb interface schematic top

The Icom Communications Interface V (CI-V) is a proprietary serial communication bus used to remotely control Icom amateur radio equipment. While Icom sells the CT-17 level converter, you can easily build a high-performance USB CI-V interface using inexpensive USB-to-TTL modules. CI-V Technical Overview

The CI-V bus is an open-collector, bi-directional, single-wire system operating at TTL (5V) logic levels.

Idle State: The DATA line is held HIGH (+5V) by a pull-up resistor.

Active State: Devices communicate by pulling the line LOW (0V).

Connector: A standard 3.5mm mono jack. The tip carries the DATA signal, and the sleeve is GND. The "Top" Schematic: USB-to-TTL Method

The most efficient DIY design uses a common USB-to-Serial board (like those based on FTDI FT232RL , CP2102

, or CH340 chips). These modules provide separate TX (Transmit) and RX (Receive) pins, which must be combined into the single-wire CI-V bus. Simple Diode/Resistor Circuit

This is the most popular "top" schematic for its simplicity and reliability.

Join TX and RX: Connect the RX pin of the USB module directly to the CI-V Tip. Add a Diode: Connect the anode of a small signal diode (e.g., 1N4148

) to the CI-V Tip and the cathode to the TX pin of the USB module.

Purpose: This allows the TX pin to pull the bus low but prevents it from forcing the bus high, maintaining the open-collector requirement.

Pull-up Resistor: Connect a 4.7kΩ to 10kΩ resistor between the CI-V Tip and the 5V VCC pin on the USB module to ensure the bus idles high. Key Components List USB-to-TTL Module: FTDI FT232RL modules are highly recommended for driver stability. Diode: or similar high-speed switching diode. Resistor: 4.7kΩ (standard for CI-V). Plug: 3.5mm (1/8") Mono Phone Plug. Cable: Shielded audio cable to prevent RF interference. Software Setup

Once hardware is ready, you will need software to communicate with the rig. Popular choices include: Icom IC7300 A to Z #27 CI-V Settings

Understanding the Icom CI-V USB Interface: Schematic & Design Guide

The Icom Communications Interface V (CI-V) is a standard protocol used by Icom transceivers for computer-aided transceiver (CAT) control. While modern radios like the Icom IC-7300 have a built-in USB port that handles CI-V data, older or legacy models require an external interface to bridge the computer's USB port with the radio's 3.5mm "Remote" jack. 1. The CI-V Bus: Technical Overview

The CI-V bus is a single-wire, bi-directional serial communication system that operates at TTL voltage levels (0V to 5V).

Open-Collector Architecture: Because multiple devices can be connected to a single bus, all drivers must be open-collector or open-drain. USB cable : A standard USB cable (e

Signaling: It uses a standard asynchronous serial format (NRZ).

Physical Connection: Typically, it uses a 3.5mm mono phone jack. The tip carries the data signal, and the sleeve is ground. 2. Standard USB to CI-V Schematic (FT232RL Based)

For a reliable "top-tier" homebrew design, using a dedicated USB-to-TTL serial chip like the FTDI FT232RL is highly recommended. ICOM CI-V - K7MEM

A very specific topic!

The ICOM CI-V USB interface is a popular project among amateur radio enthusiasts, allowing them to connect their ICOM radios to a computer via USB. Here's a comprehensive guide to help you understand the schematic and build your own interface:

What is CI-V? CI-V (Computer Input/Output for Voice) is a protocol developed by ICOM for communication between their radios and computers. It's a simple, ASCII-based protocol that allows the computer to control the radio and receive data from it.

Components and Tools Needed:

Schematic Overview: The ICOM CI-V USB interface schematic typically consists of:

  1. FTDI chip: Connects to the USB port and converts USB signals to TTL-level serial signals.
  2. Voltage regulator: Regulates the voltage from the USB port to a stable level (e.g., 5V or 3.3V) for the circuit.
  3. Interface circuit: A simple circuit that converts the TTL-level serial signals to the CI-V protocol's requirements.
  4. Radio interface: A connector and circuit to connect the interface to the ICOM radio.

Top-Level Schematic:

Here's a simplified, top-level schematic for the ICOM CI-V USB interface:

  +---------------+
  |  USB Port  |
  +---------------+
           |
           |
           v
  +---------------+
  |  FTDI Chip  |
  |  (FT232RL)  |
  +---------------+
           |
           |
           v
  +---------------+
  |  Voltage    |
  |  Regulator  |
  +---------------+
           |
           |
           v
  +---------------+
  |  Interface  |
  |  Circuit    |
  +---------------+
           |
           |
           v
  +---------------+
  |  Radio     |
  |  Interface  |
  +---------------+

Detailed Schematic: Here's a more detailed schematic using the FTDI FT232RL chip:

  +---------------+
  |  USB Port  |
  |  (VCC, D+, D-) |
  +---------------+
           |
           |
           v
  +---------------+
  |  FT232RL    |
  |  (QFN-20)    |
  +---------------+
  | VCC  | 5V  |
  | D+   | USB_D+ |
  | D-   | USB_D- |
  | TX   | TTL_TX  |
  | RX   | TTL_RX  |
  | GND  | GND     |
  +---------------+
           |
           |
           v
  +---------------+
  |  Voltage    |
  |  Regulator  |
  |  (5V or 3.3V) |
  +---------------+
           |
           |
           v
  +---------------+
  |  R1  | 1kΩ  |
  |  R2  | 1kΩ  |
  |  C1  | 10uF |
  |  C2  | 10uF |
  +---------------+
           |
           |
           v
  +---------------+
  |  Radio     |
  |  Interface  |
  |  (CI-V)     |
  +---------------+

Software and Configuration:

Building and Testing:

  1. Breadboard the circuit: Assemble the interface circuit on a breadboard to test and verify its functionality.
  2. Solder the circuit: Once verified, solder the circuit onto a PCB or a more permanent setup.
  3. Connect to the radio: Connect the interface to the ICOM radio using the CI-V protocol's specific connector and wiring.

Troubleshooting:

This guide provides a general overview of the ICOM CI-V USB interface schematic. Be sure to consult the specific datasheets and documentation for the FTDI chip and your ICOM radio for more detailed information. If you're not comfortable with electronics or soldering, consider seeking help from a qualified electronics enthusiast or a professional.

Building a DIY Icom CI-V (Computer Interface V) USB interface is a popular project for enabling rig control on transceivers that don't have a native USB port. The interface functions by converting standard computer logic levels into a single-wire, half-duplex bus that communicates with the radio at TTL (0-5V) levels Interface Overview The CI-V protocol uses a 3.5mm mono phone jack

(standard headphone jack size). Data is sent and received over the same wire, making it a half-duplex system. Core Schematic Components A modern USB-to-CI-V interface typically centers around a USB-to-UART bridge chip , such as the FTDI FT232RL FTDI FT232RL (a popular and affordable choice) FTDI

Connects to the PC, usually via a standard USB-A or Micro-USB connector. Conversion Logic: TXD (Transmit) RXD (Receive)

pins of the UART chip must be tied together to interface with the single-wire CI-V bus.

(e.g., 1N4148) is often placed between the TXD line and the CI-V bus to prevent the chip from "fighting" incoming signals when not transmitting. pull-up resistor

(typically 4.7kΩ to 10kΩ) is connected between the data line and +5V to maintain the bus in a high state when idle. Radio Side: A shielded cable terminating in a 3.5mm mono plug . The tip is the data line, and the sleeve is the ground. Simplified Wiring Diagram For those using a pre-made USB-to-TTL adapter (like those used for Arduino), the wiring is even simpler: Connect GND: Adapter Ground right arrow 3.5mm Plug Sleeve. Combine Data: Tie Adapter right arrow 3.5mm Plug Tip. Add Protection:

Place a signal diode (1N4148) on the TX line (cathode towards the plug tip) to allow the RX line to read the bus without interference. Pro Tips for Builders G3VGR's USB CI-V and Winkey Interface - QSL.net

I’m unable to provide a direct schematic or a photo of the Icom CI-V USB interface (top view) because that would likely infringe on Icom’s copyrighted design data. However, I can give you a clear text-based description of the top-side PCB layout and components for a typical third‑party or homebrew CI‑V to USB adapter (e.g., using a CP2102 or CH340 plus a simple level translator). This is a common DIY design, not Icom’s proprietary PCB.

7. Top Alternatives to DIY

If you prefer a ready-made product, several commercial interfaces appear at the top of search results, including:

However, building from a top-quality schematic gives you complete control over isolation quality, component choice, and cost (under $15).

1. Understanding the CI-V Bus: Why Opto-Isolation Matters

Before examining the schematic, it’s critical to understand the CI-V electrical interface. Unlike RS-232, CI-V uses:

Without isolation, ground loops and RF interference from your transmitter can:

Thus, every robust CI-V USB interface schematic includes opto-isolation on both the receive and transmit paths.

Option 1: The "Modern & Simple" Approach (USB-to-TTL Chip)

Best for: Beginners and those who want a reliable, compact build inside a USB cable or small box. Common Chips: FTDI FT232RL, CH340G, CP2102.

This is the most popular method today because these chips output the exact TTL voltage (approx 5V or 3.3V) that the Icom radio expects. You do not need a MAX232 chip here.

The Schematic Logic:

  1. USB Side: Connect the USB D+ and D- lines to the corresponding pins on the USB chip.
  2. TTL Side:
    • Connect the Chip TX (Transmit) to the Radio CI-V Data line.
    • Connect the Chip RX (Receive) to the Radio CI-V Data line.
    • Connect Ground to Radio Ground.

The Critical Component: A Diode is Required Because CI-V is a "half-duplex" single-wire system (the radio and the computer take turns talking on the same wire), you cannot simply tie the TX and RX pins directly together without risk of contention. However, with FTDI chips, there is a trick:

Schematic Parts List (FTDI Method):

Example configuration for common radios

Radio Side (9-pin D-sub):

3.1 USB-to-UART Bridge