Icom Ci V Usb Interface Schematic Top [hot] -

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

The Icom CI-V USB interface serves as a bridge between a computer's USB port and the single-wire, bidirectional CI-V (Computer Interface 5) bus used by Icom transceivers for rig control. Core Schematic Components

A modern USB-to-CI-V interface typically revolves around a dedicated USB-to-Serial converter chip, such as the FTDI FT232RL Go to product viewer dialog for this item. .

USB Interface: A USB Type-B or Micro-USB jack connects to the host computer. USB-to-Serial Chip : The (or similar chips like the

) handles the USB protocol and provides TTL-level serial signals (TX and RX).

Signal Conversion (Combining TX/RX): Because the CI-V bus is a single-wire system, the unidirectional TX and RX lines from the chip must be combined. This is often done using:

Diodes/Resistors: A simple passive circuit using a switching diode (like a 1N4148) and a pull-up resistor to combine the lines into one.

Logic Buffers: Some designs use a hex buffer (e.g., 7417 or 4049) to isolate and combine signals for better stability. icom ci v usb interface schematic top

Radio Connector: A 3.5mm mono phone plug is the standard physical connection to the radio's "REMOTE" jack.

RFI Suppression: Ferrite beads and small bypass capacitors (e.g., 0.01 µF) are often added to the data lines to prevent radio frequency interference from disrupting the connection. Typical Circuit Layout Key Design Considerations

Isolation: High-end designs may include opto-isolators to prevent ground loops between the computer and the radio.

Power: The interface is typically powered directly from the computer's 5V USB bus, eliminating the need for an external power supply.

Drivers: If building your own, ensure you install the appropriate Virtual COM Port (VCP) drivers from the chip manufacturer (e.g., FTDI) to allow software like Ham Radio Deluxe or FLDigi to communicate with the rig. Explore USB with this USB to CI-V Interface - N5DUX

Building a DIY Icom CI-V USB interface is a popular project for amateur radio operators looking to avoid the high cost of official cables like the Icom CT-17

. This guide covers the schematic and construction for a modern USB-to-CI-V interface using an FTDI chip. 1. Circuit Schematic & Operation The core of a modern USB CI-V interface is a USB-to-TTL UART converter

. Icom's CI-V bus uses a single-wire, bi-directional TTL (0–5V) signal where both transmit (TX) and receive (RX) data are combined onto one line. USB Controller FTDI FT232RL

is the most common choice as it handles all USB-to-serial conversion. The "Combining" Diode

: Since CI-V is a single-wire bus, you must connect the TXD and RXD pins of your USB chip together. A common method is connecting the RXD pin directly to the CI-V bus and using a 1N4148 diode CI-V (Computer Interface V) system is a standard

(anode to RXD/CI-V, cathode to TXD) to prevent the radio from being driven high by the TX pin when idle.

: Some designs include ferrite beads on the data and power lines to block stray RF noise. 2. Bill of Materials (BOM) You can find these parts at retailers like Specification FTDI FT232RL or CP2102 USB-to-UART Bridge Combines TX/RX for single-wire CI-V Pull-up resistor for the data line Capacitors 0.1 µF & 100 pF Noise bypassing and filtering 3.5mm Mono Plug Standard CI-V "Remote" jack connection Shielded Audio Cable Prevents RF interference 3. Construction Steps Prepare the USB Module

: If using a pre-made CP2102 or FT232RL breakout board, identify the Solder the Bridge

: Solder the 1N4148 diode and 10k resistor between the TXD and RXD pins as specified in your chosen schematic to create the single-wire bus. Wire the 3.5mm Jack Connect the of the 3.5mm mono plug to the combined TXD/RXD line. Connect the to the GND pin of the USB module.

: Many builders use a small plastic project box or even a "Manhattan style" construction on a piece of unetched PCB board for a solid ground plane. www.ka6wke.net 4. Software Setup Explore USB with this USB to CI-V Interface - N5DUX

a USB to CI-V interface you can use. to control a radio with CI-V remote control. port capability and common radio frequency. USB- ICOM CI-V - K7MEM

The workbench was a graveyard of half-finished projects until the ICOM CI-V interface arrived. For a radio op, it wasn’t just a cable; it was the bridge between a legacy rig and modern digital wizardry.

I remember staring at the top-down schematic, a clean blueprint of logic in a world of messy RF. At the heart sat the FT232R chip, the silent translator converting USB’s frantic data into the steady, open-collector pulses the ICOM radio understood. To its left, a single 1N4148 diode stood guard—a simple gatekeeper ensuring the TX and RX lines played nice on the single-wire bus without talking over each other.

The "Top" view of the PCB layout was a work of art. Traces curved like copper rivers, snaking around tiny 0.1µF capacitors that filtered out the hum of the Shack’s power supply. I remember the smell of fresh solder as I bridged the pads, following the diagram's path from the USB-B port straight to the 3.5mm mono jack.

When the last joint cooled, I plugged it in. The computer chimed, the rig’s frequency flickered to life on the screen, and just like that, the schematic wasn’t a drawing anymore—it was a conversation. Ensure that the cable used for the CI-V

Notes:

Ensure that the cable used for the CI-V connection is not too long, as this can affect signal integrity.
Be careful with the PTT and other signals not used by CI-V; they might be used by other software or functions.
The success of the project depends on the correct assembly, configuration, and communication software setup.

This guide provides a basic understanding. For detailed electronics expertise and specific component values (like which resistors and capacitors are needed), refer to FTDI documentation and Icom's CI-V protocol specifications. Always follow best practices for electronics assembly and safety.

Signal Flow:

PC → Radio (Transmit path):
- U1’s TxD (TTL, active high) → resistor → Base of Q1 (NPN).
- Q1 inverts signal → Collector of Q1 becomes open-collector output (active low).
- Collector connects directly to CI-V data line (via a diode to protect from external voltage).
- Result: USB ‘high’ = CI-V line low (proper inversion).
Radio → PC (Receive path):
- CI-V data line (open-collector, active low) → connected directly to U1’s RxD (TTL).
- However, because RxD expects “idle high” and CI-V is “idle low” → A pull-up resistor (e.g., 4.7kΩ) on RxD to Vcc (3.3V/5V) fixes the idle state.
- Result: CI-V low = USB RxD low (direct logic, but idle states must match).

Many cheap interfaces omit the inversion on TxD and just swap RX/TX – this fails with Icom because the protocol expects the idle state inversion.

If you need the exact Icom PCB top artwork

Icom’s official interface (e.g., CT‑17 or internal USB in IC‑7300/9700) is proprietary. You can:

Search for “Icom CI-V USB interface schematic service manual” – some models include PCB layout in the service manual (e.g., Icom CT‑17 service manual).
Look at open source projects:
- “USB to CI-V interface” on GitHub (search for CI-V + CP2102).
- QRPblog or DL2LBO designs – they publish full PCB top views (Gerber files).

3.5 Power Supply

Most interfaces are bus-powered from USB.

USB +5V → powers USB side of optocouplers and the FTDI chip.
Radio side +5V must be sourced from the CI-V connector (Pin 2 of the 3.5mm jack – note: some Icoms provide ~8V; use a 5V regulator (78L05) if needed).

Alternatively, a separate isolated DC-DC converter (e.g., B0505S) can generate a floating 5V for the radio side, eliminating the need to draw power from the radio.

Testing and troubleshooting

With no radio, measure CI-V node idle voltage (should be pulled high ~5V if pull-up present).
Use a terminal program (set correct COM port, baud, 8N1) and send known CI-V commands; observe responses.
If no response, try adding/removing external pull-up, check inversion, verify ground connection, insert optocoupler if noise suspected.

4. Critical Design Considerations for the “Top” Interface

If you are building or buying such an interface, here is what the schematic tells you about performance:

| Requirement | Why it matters | |-------------|----------------| | Open-collector driver (Q1) | CI-V is a shared bus; multiple devices can drive it low. A standard totem-pole output would short-circuit. | | Pull-up resistor (~4.7kΩ) | Ensures CI-V line idle high without current drain. | | Diode protection | Prevents CI-V voltage (5-12V accident) from back-driving FTDI chip. | | No ground loops | The interface should have opto-isolation (advanced) or at least common ground – but a direct ground is acceptable for single radio. | | Inversion as per Icom spec | Without correct inversion, commands will be byte-swapped or corrupt. |

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

Where to Find Verified Schematics

G4ILO’s USB CI-V interface – Classic single-transistor design (2N7000)
K0BG CI-V interface page – Includes PCB layout
ICOM IC-7300 USB CI-V notes – Built-in USB already, but external cloning exists
GitHub / Electro-Tech – Search “CI-V USB schematic”