This comprehensive guide covers the technical theory, essential schematics, and construction steps required to build a reliable, high-performance DIY Icom CI-V USB interface. 1. Understanding the Icom CI-V Protocol
The protocol has been the standard for amateur radio rig control for decades . As computers have evolved, the need to bridge this old-school serial protocol with modern USB ports has become essential. Understanding the Icom CI-V USB interface schematic is key for DIYers, homebrewers, and those looking to integrate older Icom radios (like the IC-706, IC-735, IC-746) or modern ones (IC-7300, IC-9700) with computers, logging software, and digital mode software (e.g., WSJT-X, FLDigi). icom ci v usb interface schematic top
The Icom CI-V system is a serial communication protocol used to control Icom radios. It uses a simple two-wire interface (Data and Ground) that operates at TTL logic levels (5V). As computers have evolved, the need to bridge
The critical point often omitted in simplified "USB to CI-V" diagrams is . Because CI-V is a shared bus, multiple devices can transmit on the same pair of wires. In practice, this means the TX line from the UART cannot be connected directly to the radio's REMOTE tip. Instead, a buffer IC such as the 7417 hex buffer must be placed between the UART and the CI‑V bus to emulate an open‑collector output. It uses a simple two-wire interface (Data and
This path carries data from PC TXD to the CI-V bus.
: It utilizes a CSMA/CD system to manage traffic on the shared bus, ensuring over 90% bus efficiency. Schematic Topography and Key Components
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.