The USB-to-TTL adapter provides the +5V power and ground for the circuit. The critical part is the "CI-V Level Shift" block, which manages the bidirectional communication.
If you are worried about ground loops, induced noise from amplifiers, or potential damage to your transceiver, opto-isolation is the best choice.
Creating a USB interface for the Icom CI-V, a protocol used by Icom radios for computer communication, involves designing a simple interface that converts the CI-V's serial signal to a USB signal that a computer can understand. The CI-V protocol uses a 9-pin D-sub connector with a specific pinout and typically operates at 9600 bps.
By following the N5DUX or G3VGR schematics, you can build a highly effective interface, saving money and gaining a deeper understanding of your Icom radio.
Before looking at the hardware, it helps to understand how CI-V communicates. icom ci v usb interface schematic top
The TXD pin on the FTDI chip connects through a diode to the shared CI-V line. The RXD pin connects to the same line, allowing for bidirectional communication. A 4.7kΩ resistor acts as a pull-up to ensure stable 5V TTL levels [N5DUX].
Once constructed, you need to configure the system to recognize the interface.
If you tell me which Icom radio model you are using (e.g., IC-7300, IC-7000), I can provide the exact pinout and recommended interface configuration .
Top Icom CI-V USB Interface Schematics: DIY Guide and Design Principles The USB-to-TTL adapter provides the +5V power and
For this to work reliably, any circuit driving the CI-V bus . This ensures that when a device is not transmitting, it effectively "releases" the bus line so other devices can talk. The bus line is held in a high (logic 1) state by a pull-up resistor, and a device transmits by pulling it low (logic 0).
Because the classic RS‑232 interface draws power from the DTR signal, the schematic often shows DTR (pin 4) connected to a regulator or diode‑based power supply. USB‑to‑RS‑232 converters may or may not provide enough current for this method.
USB-to-UART Module (5V TTL) +---------------------------+ | | | TXD --------------------+---------->|-----+ | | 1N4148 | | RXD <-------------------|-----------------+-----> To 3.5mm Plug TIP | | | | GND --------------------|-----------------+-----> To 3.5mm Plug SLEEVE | | +---------------------------+
The Icom CI-V (Computer Interface 5) USB interface schematic typically centers around a , such as the FTDI FT232RL Go to product viewer dialog for this item. Go to product viewer dialog for this item. Creating a USB interface for the Icom CI-V,
At the hardware level, CI-V is a that operates at TTL voltage levels (0 and +5V) . It uses a single data line plus a ground, a significant difference from the separate Transmit (TX) and Receive (RX) lines found on a standard RS-232 or USB serial port.
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
Hence, the interface sits between a USB port and the radio's REMOTE jack. The electrical interface is simple (tip is CI-V data, sleeve is ground), but successfully implementing it requires understanding in detail.