Icom Ci V Usb Interface Schematic Top !new! Today

: The interface converts standard computer signals to the 5V (TTL) levels required by the radio.

~40×20 mm (e.g., similar to a CP2102 breakout)

USB-to-UART Module (5V TTL) +---------------------------+ | | | TXD --------------------+---------->|-----+ | | 1N4148 | | RXD <-------------------|-----------------+-----> To 3.5mm Plug TIP | | | | GND --------------------|-----------------+-----> To 3.5mm Plug SLEEVE | | +---------------------------+

+5V (from USB or Rig) | [ 4.7k ] | RS232 TXD o--[ 10k ]--+--| Base (PNP BC557) | Emitter o-------> To CI-V Tip (3.5mm) | Collector | GND Use code with caution. icom ci v usb interface schematic top

is used to handle the voltage translation between +/-12V (RS-232) and 0-5V (TTL).

Place a SMD ferrite bead on both the USB 5V line and the CI-V tip line.

Draw a physical clearance gap (at least 2mm to 5mm wide) across the board. No copper traces, ground planes, or power planes should cross this line. The only components spanning this gap must be the physical bodies of the optocouplers. : The interface converts standard computer signals to

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

Check the baud rate in software (e.g., FLDigi) matches the radio's "CI-V Baud Rate" setting.

The RXD pin constantly listens to the bus. When the radio pulls the bus Low, the computer reads it immediately. Place a SMD ferrite bead on both the

Look under "Ports (COM & LPT)" to identify the allocated port number (e.g., ).

USB TTL TxD ---- 10k ----- Base of NPN Emitter - GND Collector ---- 1N4148 ---- CI-V data line | +--- 4.7k pull-up to 5V CI-V data line ---------------------------------------------- USB TTL RxD (with internal pull-up enabled)

(e.g., 1N4148) is often placed between the TXD line and the CI-V bus to prevent the chip from "fighting" incoming signals when not transmitting. pull-up resistor