Building Your Own Icom CI-V USB Interface: A Complete Schematic Guide
The CT‑17 is designed for RS‑232, not USB. It uses a MAX232 or similar chip to convert RS‑232 levels to TTL. Modern homebrew designs replace the RS‑232 portion with a USB‑to‑TTL UART, but the open‑collector bus driver remains essential.
Here are the three most common schematic topologies, ranging from the easiest to build to the most traditional.
Connect the anode of the diode to the RXD pin using a small piece of hookup wire. icom ci v usb interface schematic top
The story of the 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
pull-up resistor (R5) between and the 3.5mm Jack Tip .
The RXD pin constantly listens to the bus. When the radio pulls the bus Low, the computer reads it immediately. Building Your Own Icom CI-V USB Interface: A
Connect the cathode (Pin 3) of directly to the 3.5mm Jack Tip . Install a 4.7
This document explains how to build a USB-to-Icom CI-V interface (PC ↔ Icom radio control bus), gives a recommended schematic, component values, wiring notes, and safety/EMC tips.
Typically a 3.5mm (1/8") mono jack marked "REMOTE". Connection: Pin 1 (Tip) is data, Pin 2 (Sleeve) is ground. Here are the three most common schematic topologies,
: 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.
USB SIDE (Non-Isolated) | RADIO SIDE (Isolated) | +-----+ +-----------+ | +------------+ | |--TX-->| |--Isol. TX---|--+---| Steering | 3.5mm Jack | USB | | Digital | | | | Diode | /| | Chip| | Isolator | | \ | Network |----| |--- TIP (CI-V) | |--RX--<| |<-Isol. RX---|--+---| | | | +-----+ +-----------+ | +------------+ \|--- SLEEVE (GND) | | | | | GND GND1 | GND2 GND2 The Steering Diode Network
on the data line is crucial for the open-collector bus to work properly. 4. Setting Up the Interface (Software & Hardware)
If you do not want to solder surface-mount ICs like the FT232RL, buy a cheap . Connect the board's GND to the 3.5mm jack Sleeve .