Icom Ci V Usb Interface Schematic Top Page

I couldn’t find a specific top-level schematic titled exactly “ICOM CI-V USB Interface Schematic Top” in public databases. However, the CI-V (Computer Interface V) is ICOM’s proprietary control bus for radios (e.g., IC-703, IC-706, IC-718, IC-7300, etc.). A typical USB-to-CI-V interface uses a USB-to-serial bridge chip (FT232RL, CP2102, CH340) combined with a level converter (since CI-V is TTL-level, not RS-232).

Top Resources for ICOM CI-V USB Interface Schematic icom ci v usb interface schematic top

• Standard Hack: Connect the USB Chip TX pin to the CI-V Data line. Then, place a signal diode (like a 1N4148 or 1N914) with the cathode (stripe) facing the TX pin and the anode facing the RX pin. This allows the RX pin to "listen" to the line while the TX pin drives it.
• The "Pro" Method (Open Collector): Many builders prefer to configure the FT232RL chip to use its CBUS pins. You can program one CBUS pin to act as a "Tx Enable" and use a transistor (like a 2N3904) to create an open-collector driver. This mimics the official Icom design perfectly and prevents data collisions.

6. Building Your Own CI-V USB Interface: Step-by-Step

Bill of Materials (Top-Level BOM)

| Component | Value / Part | Quantity | |--------------------|------------------------|----------| | UART bridge | FT232RL or CH340G | 1 | | Optocoupler (fast) | 6N137 or PC900 | 2 | | NPN transistor | 2N3904 / 2N2222 | 1 | | Resistor kit | 330Ω, 560Ω, 1k, 2.2k, 4.7k, 10k | each | | Capacitors | 0.1µF, 10µF (electrolytic) | few | | 3.5mm TRS jack | Stereo, PCB mount | 1 | | USB connector | USB-B or micro-USB | 1 | | Ferrite beads | 600Ω @ 100MHz | 2 | | 78L05 regulator | (if radio provides >5V) | 1 (opt) | I couldn’t find a specific top-level schematic titled

Signaling: It uses a standard asynchronous serial format (NRZ). Standard Hack: Connect the USB Chip TX pin

Designing and Building an ICOM CI-V USB Interface

Before building or purchasing an interface, compare the vendor’s schematic against this “top” design. If it lacks the open-collector NPN inverter stage on the transmit line (or uses a simple transistor without correct biasing), it will likely fail with Icom’s protocol.

• TXD (output from computer)
• RXD (input to computer)
• DTR/RTS optional for power or reset.

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.