+---------------+ | 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) | +---------------+
: Some designs use a hex buffer (e.g., 7417 or 4049) to isolate and combine signals for better stability.
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)
Understanding the Icom CI-V USB Interface: Schematic & Design Guide