Icom Ci V Usb Interface Schematic Top -

(Computer Interface V) system is a bi-directional, single-wire serial bus used to control Icom amateur radio transceivers. While modern rigs like the Icom IC-7300

3.2 Opto-Isolation Stage (Computer → Radio)

Modern computers no longer have serial ports (RS-232), and CI-V is not directly compatible with USB. Therefore, an interface is required to bridge the gap. The schematic design depends entirely on which USB chip you choose to use. icom ci v usb interface schematic top

• The MAX232 chip takes the high RS-232 voltages and converts them to 5V TTL.
• RS-232 TX (Pin 3 of DB9) $\rightarrow$ MAX232 Input $\rightarrow$ TTL Output.
• RS-232 RX (Pin 2 of DB9) $\leftarrow$ MAX232 Output $\leftarrow$ TTL Input.

Merging TX and RX

: Connect the TX and RX lines together. To prevent contention, it is common to: The MAX232 chip takes the high RS-232 voltages

CI-V requires an open-collector driver.