Icom Ci V Usb Interface Schematic Top __exclusive__ Jun 2026

Connect a between the TXD line and the RXD line. The cathode (the side with the stripe) must face the TXD pin of the serial chip.

Do you prefer using or an off-the-shelf breakout board ?

Most USB-powered interfaces are simple. The 5V from the USB port powers the USB bridge IC and the 5V logic of the bus driver circuit. Some older designs, especially those based on RS-232, used the modem control lines for power, which is a convenient trick for serial ports but less relevant for modern USB designs.

+---------------+ | 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) | +---------------+ icom ci v usb interface schematic top

The TXD and RXD pins of the FTDI chip are connected together through a diode (1N4148) with the cathode facing the TXD pin.

It requires a bidirectional to unidirectional conversion, as the computer expects separate RX and TX lines, while the radio uses one shared line. 2. Top CI-V USB Interface Schematics (DIY)

While commercial cables are widely available, building your own CI-V to USB interface is a rewarding, low-cost project. This guide provides a highly efficient, field-tested schematic design to bridge your PC's USB port with your radio's CI-V port. Understanding the CI-V Protocol Connect a between the TXD line and the RXD line

You cannot connect a USB-to-RS-232 cable directly to the CI-V port because RS-232 uses ±12Vplus or minus 12 cap V

When the radio transmits a logic low, it pulls the CI-V line down, which completes the circuit for the RX optocoupler's input LED, sending the logic low back to the PC RXD pin. 4. RF Noise Filtering

CI‑V uses (one‑wire bidirectional data). The USB side (UART) is standard TTL (non‑inverted). So you need: Most USB-powered interfaces are simple

Before diving into the USB interface schematic, it's essential to understand the ICOM CI-V protocol. CI-V is a communication protocol developed by ICOM, a Japanese company renowned for its high-quality amateur radio equipment. The CI-V protocol allows ICOM radios to communicate with external devices, such as computers, using a serial interface. This protocol enables features like remote control, frequency setting, and data transmission.

Combine the separate TX and RX lines into a single, bi-directional 3.5mm mono line without causing data collisions. The Core Schematic Components

Once built, plug the interface into your PC. Windows, macOS, and Linux usually install FTDI or CH340 drivers automatically.

Connect the RXD line directly to the Tip of the 3.5mm mono jack.

There are three primary ways to design a DIY CI-V to USB interface. Below are the top schematics ranging from modern, streamlined chips to classic transistor designs.