Icom Ci V Usb Interface Schematic Top [patched] [EASY »]

The story of the Icom CI-V (Communication Interface-V) is one of elegant simplicity in the face of complex technology. While other manufacturers often reinvented the wheel with every new radio, Icom’s standard has remained remarkably consistent since its introduction in the late 1980s. The Birth of a Standard

Developed in 1991 by Icom Inc. in Osaka, Japan, CI-V was actually the company's fifth attempt at a communication interface—hence the Roman numeral "V". Its original purpose wasn't just computer control; it was designed to allow separate receivers and transmitters to act as a single, unified transceiver.

Every major Icom HF transceiver since the IC-735 has featured a CI-V port on its back panel. This persistence turned CI-V into a "lingua franca" for radio enthusiasts, allowing a single interface design to work across decades of equipment. The Schematic: Elegance in "One Wire"

At its heart, the CI-V bus is a single-wire, bi-directional TTL signaling system.

The Logic: It uses an "open collector" bus where the data line is held high when idle. Any device can "talk" by pulling that line low, using a collision detection system similar to early Ethernet.

The "Top" Interface Strategy: Because computers traditionally use RS-232 serial ports (with separate transmit/receive lines) and modern computers use USB, the "top" schematic for a CI-V interface is essentially a level converter.

DIY Spirit: Hams often bypass expensive official adapters by building their own using the MAX232 IC (for older serial ports) or the FTDI232RL chip (for USB). A classic "minimalist" schematic uses just three transistors and three resistors to combine those separate computer signals into the single CI-V bus. The USB Revolution

An Icom CI-V USB interface acts as a bridge between a modern computer's USB port and the TTL-level serial bus used by Icom transceivers for remote control. While commercial versions can be expensive, a DIY interface is highly effective and can be built using standard USB-to-UART components. Core Interface Features

Single-Wire Communication: The CI-V (Computer Interface 5) protocol uses a bi-directional, single-wire TTL signaling system where a single "DATA" line is held high until a device pulls it low to initiate communication. USB-to-Serial Conversion

: Modern schematics center around a bridge IC, most commonly the FTDI FT232RL Go to product viewer dialog for this item. or the Silicon Labs CP2102 Go to product viewer dialog for this item. icom ci v usb interface schematic top

. These chips convert USB data into standard asynchronous serial signals.

Logic Level Shifting: The interface converts standard computer signals to the 5V (TTL) levels required by the radio.

Collison Management: It utilizes a CSMA/CD system to manage traffic on the shared bus, ensuring over 90% bus efficiency. Schematic Topography and Key Components

Building a USB CI-V interface generally involves three main functional blocks: G3VGR's USB CI-V and Winkey Interface - QSL.net

CI-V (Computer Interface V) system is a standard protocol used by Icom transceivers for remote control. Because it uses an open-collector, half-duplex TTL-level signal, it requires an interface to convert these signals to levels a computer can understand, such as USB. Core Schematic Components A modern USB-to-CI-V interface typically revolves around a USB-to-Serial UART chip (like the FTDI FT232RL or Silabs CP2102). USB Bridge Chip : Converts USB data into TTL (0–5V) serial signals. Diode & Resistor Combination

: Since CI-V combines Transmit (TX) and Receive (RX) onto a single wire, a small circuit is needed to bridge the TX and RX pins of the UART chip. 3.5mm Mono Jack

: The standard physical connection for the radio end of the cable. Top Schematics & Design Options CI-V interface - Tučňák Wiki Tucnak - Nagano.cz Easy to make CI-V cable www.maniaradio.it Simple Icom CI-V Interface Yet Another ICOM CI-V Interface circuit | Next Electronics Next.gr Electronics Icom CI-V Interfaces and CT-17 Replacement – VK4AMG

ICOM CI-V to RS232 interface diagram (using transistors, very small) ICOM CI-V Interface Seed Solutions CI-V interface - Tučňák Wiki Tucnak - Nagano.cz icom ci-v interface KA1MDA HOME PAGE

To build a DIY Icom CI-V USB interface, you typically use a USB-to-TTL serial adapter (like those based on the CP2102 or FT232 chips) combined with a simple circuit to merge the separate TX and RX lines into the single-wire bidirectional CI-V bus. Interface Schematics & Visuals Core Circuit Design The story of the Icom CI-V (Communication Interface-V)

The Icom CI-V bus is a single-wire, bidirectional bus where logic levels are roughly 0V (low) and 5V (high). To connect this to a computer via USB, follow these steps:

USB-to-TTL Adapter: Use a cheap module (e.g., from Aliexpress) to convert USB signals to 5V (or 3.3V) serial TTL levels.

Merging TX and RX: Connect the TX and RX lines together. To prevent contention, it is common to:

Connect TX to RX through a diode (1N4148) with the cathode toward the TX pin.

Add a 10k ohm pull-up resistor from the combined line to VCC (5V) to ensure the signal stays high when idle.

The Connector: Use a 3.5mm mono jack. The combined TX/RX signal goes to the Tip, and the module's GND goes to the Sleeve. Key Build Tips

Open-Collector Drive: For maximum safety and to avoid bus contention, some builders recommend using an open-collector buffer (like the 7417 hex buffer) instead of a simple diode.

Isolation: If you have issues with RF in your shack, consider adding ferrite chokes or isolation transformers to the signal lines.

Drivers: Always download the specific Icom USB drivers or the drivers for your specific serial chip (FTDI, CP2102) before connecting the hardware to your PC. Understanding the Icom CI-V USB Interface: A Top-Level

Software: Once built, you can use the interface with software like Ham Radio Deluxe or FLDigi for rig control and digital modes. 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.

Understanding the Icom CI-V USB Interface: A Top-Level Schematic Analysis

For decades, Icom has used its proprietary CI-V (Communication Interface-V) protocol to allow computers and accessories to control their transceivers (e.g., IC-7300, IC-9700, IC-705). While modern radios often include built-in USB ports, older or mid-tier models require an external "CI-V USB interface." This article dissects the top schematic of a typical universal Icom CI-V to USB converter.

Important Notes

Would you like a full component list, PCB layout example, or a specific IC’s connection diagram (e.g., FT232RL + 2N7000)?

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.

USB Side:

Typical CI-V USB Interface Schematic (Topology)

USB Type-B              USB-to-UART             Level Shifter           CI-V (to radio)
─────────              ──────────────          ─────────────            ─────────────
VBUS ────────────────► VCC (5V)
                      │
D+ ──────────────────► USBD+ (FTDI/CP2102)
D- ──────────────────► USBD-
                      │
GND ──────────────────► GND
                      │
                      TXD ──────────┬──────────► Level Shifter (e.g., 2N7000 or MAX232)
                      RXD ◄─────────┼──────────►
                      │             │
                      └─── 10k pull-up to 5V ──┐
                                               │
                                          ┌────┴────┐
                                          │ 2N7000  │
                                          │ MOSFET  │
                                          └────┬────┘
                                               │
                         CI-V Data ────────────┘ (Open collector)
                         (3.5mm jack tip)
                         GND ─────────────────── (sleeve)

Important connections for a correct CI‑V interface

CI‑V uses inverted, open‑collector logic (one‑wire bidirectional data).
The USB side (UART) is standard TTL (non‑inverted). So you need:

  1. From UART TX → CI‑V data: Inverter + open drain
    • Example: N‑channel MOSFET (2N7002) with gate = UART TX, drain = CI‑V data, source = GND.
  2. From CI‑V data → UART RX: Inverter + protection
    • Example: Same drain signal goes to UART RX via a 1k resistor and a second MOSFET or Schottky clamp.

Simplest working schematic (top‑side parts):

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)

CI‑V connector:

Tip (data) ──┬─ 4.7k pull‑up to 5V or radio Vcc

└─ drain of Q1 and 1k to RX

Ring ──────── GND

Sleeve ────── (optional +5V out)