IC-705 USB Serial Backend Setup (macOS)

This guide shows how to control the IC-705 via USB serial CI-V + USB audio devices instead of the default LAN backend.

Why Use the Serial Backend?

• No network required — direct USB connection
• Lower latency — no UDP/network overhead
• Simpler setup — no IP config, username, or password
• Field operation — works without WiFi/Ethernet
• Portable operation — ideal for IC-705's portable/QRP use case

Hardware Requirements

• IC-705 portable transceiver (HF/VHF/UHF)
• USB-C cable (IC-705 uses USB-C)
• macOS computer (tested on Ventura+ arm64/Intel)

Radio Configuration

Critical Setup Step

On the IC-705, navigate to Menu → Set → Connectors → CI-V → CI-V USB Port and set it to Link to [CI-V], NOT [REMOTE].

• Link to [CI-V] — serial CI-V commands work (required for icom-lan serial backend)
• [REMOTE] — RS-BA1 mode, serial CI-V is blocked

This is the same critical setting as IC-7610; confirmed by wfview reference and IC-7610 hardware validation.

Recommended Radio Settings

Setting	Value	Why
CI-V USB Port	Link to [CI-V]	✅ Required — enables serial CI-V
CI-V USB Baud Rate	115200	Recommended for scope/waterfall
CI-V Address	0xA4 (IC-705 default)	Library auto-detects from profile
USB Audio TX	Enabled	Allows browser/WSJT-X TX via USB audio
USB Audio RX	Enabled	Exports RX audio to computer

Baud Rate

• 115200 baud is recommended for scope/waterfall capability
• Lower baud rates (19200, 9600) work for basic control (freq, mode, PTT) but scope/waterfall is disabled by a guardrail due to high packet rate
• CI-V baud rate IS significant on IC-705 — it must match between radio and library

IC-705 Single Receiver

The IC-705 has a single receiver, unlike the IC-7610's dual receiver. The library automatically enforces this via the IC-705 profile — operations on receiver=1 will fail with CommandError.

macOS Setup

1. Install icom-lan

pip install icom-lan

# For serial CI-V control:
pip install icom-lan

# For USB audio RX/TX and audio-device listing:
pip install 'icom-lan[serial,bridge]'

# serial: pyserial + pyserial-asyncio
# bridge: sounddevice + numpy + opuslib

2. Connect the Radio

1. Power on the IC-705
2. Connect USB-C cable from Mac to IC-705 USB-C port (top panel)
3. Wait ~5 seconds for macOS to enumerate the device

3. Find the Serial Device

# List serial devices
ls -l /dev/cu.usbserial-*

# Example output:
# /dev/cu.usbserial-IC705123

The IC-705 typically appears as /dev/cu.usbserial-* where the suffix may include "IC705" or the radio's serial number.

You can also use icom-lan discover --serial-only to find USB-connected radios automatically:

icom-lan discover --serial-only

IC-705:
  • Serial: /dev/cu.usbserial-IC705123 (115200 baud)

4. Find USB Audio Devices

# List available audio devices
icom-lan --list-audio-devices

This command requires the optional bridge dependencies:

pip install 'icom-lan[bridge]'

Example output:

[
  {
    "index": 0,
    "name": "IC-705",
    "max_input_channels": 2,
    "max_output_channels": 2,
    "default_samplerate": 48000.0
  },
  {
    "index": 1,
    "name": "IC-705 TX",
    "max_input_channels": 0,
    "max_output_channels": 2,
    "default_samplerate": 48000.0
  },
  {
    "index": 2,
    "name": "IC-705 RX",
    "max_input_channels": 2,
    "max_output_channels": 0,
    "default_samplerate": 48000.0
  }
]

Audio Device Names

IC-705 USB audio devices may appear as: - IC-705 (combined RX/TX) - IC-705 RX (receive audio from radio) - IC-705 TX (transmit audio to radio)

The library will auto-detect these devices when you use the serial backend with audio enabled.

Usage Examples

CLI: Basic Control

# Connect via USB serial (no audio)
icom-lan --backend serial --device /dev/cu.usbserial-IC705123 \
  --model IC-705 --baudrate 115200 repl

# Connect with USB audio enabled
icom-lan --backend serial --device /dev/cu.usbserial-IC705123 \
  --model IC-705 --baudrate 115200 \
  --rx-audio-device "IC-705 RX" \
  --tx-audio-device "IC-705 TX" \
  repl

REPL commands:

>>> freq
7074000
>>> freq 14074000
>>> mode
('USB', 2)
>>> mode LSB
>>> ptt on
>>> ptt off

Python: Async API

import asyncio
from icom_lan.backends.factory import create_radio
from icom_lan.backends.config import SerialBackendConfig

async def main():
    # Create IC-705 serial backend
    config = SerialBackendConfig(
        device="/dev/cu.usbserial-IC705123",
        model="IC-705",
        baudrate=115200,
        rx_audio_device="IC-705 RX",  # Optional
        tx_audio_device="IC-705 TX",  # Optional
    )

    radio = create_radio(config)

    async with radio:
        # Get frequency
        freq = await radio.get_frequency()
        print(f"Frequency: {freq} Hz")

        # Set frequency (14.074 MHz USB for FT8)
        await radio.set_frequency(14_074_000)
        await radio.set_mode("USB")

        # Get mode
        mode, filt = await radio.get_mode()
        print(f"Mode: {mode}, Filter: {filt}")

        # Note: IC-705 has single receiver only
        # receiver=1 operations will fail

asyncio.run(main())

Python: Sync API

from icom_lan.backends.factory import create_radio
from icom_lan.backends.config import SerialBackendConfig

# Create IC-705 serial backend
config = SerialBackendConfig(
    device="/dev/cu.usbserial-IC705123",
    model="IC-705",
    baudrate=115200,
)

radio = create_radio(config)

with radio:
    # Sync operations
    radio.set_frequency(7_074_000)
    freq = radio.get_frequency()
    print(f"Frequency: {freq} Hz")

    radio.set_mode("LSB")
    mode, filt = radio.get_mode()
    print(f"Mode: {mode}, Filter: {filt}")

Web UI

# Start web server with IC-705 serial backend
icom-lan --backend serial --device /dev/cu.usbserial-IC705123 \
  --model IC-705 --baudrate 115200 \
  --rx-audio-device "IC-705 RX" \
  --tx-audio-device "IC-705 TX" \
  web

# Open browser to http://localhost:7610

The web UI provides: - Frequency/mode control - VFO select/swap - Scope/waterfall display - Audio bridge (browser → radio TX, radio RX → browser) - PTT control - Memory/filter/settings panels

rigctld (Hamlib Compatibility)

# Start rigctld server with IC-705 serial backend
icom-lan --backend serial --device /dev/cu.usbserial-IC705123 \
  --model IC-705 --baudrate 115200 \
  rigctld --port 4532

# Test with rigctl client
rigctl -m 2 -r localhost:4532 f  # Get frequency
rigctl -m 2 -r localhost:4532 F 14074000  # Set frequency

Troubleshooting

Serial Device Not Found

# Check if USB device enumerated
system_profiler SPUSBDataType | grep -A 10 "IC-705"

# Check for any serial devices
ls -l /dev/cu.*

Solutions: - Verify USB-C cable is data-capable (not charge-only) - Try a different USB port on your Mac - Power cycle the IC-705 and wait for enumeration - Check macOS System Settings → Privacy & Security → USB permissions

CI-V Commands Failing

Symptoms: Connection succeeds but commands timeout or return NAK

Solutions: 1. ✅ Verify CI-V USB Port = Link to [CI-V] (most common issue) 2. Check CI-V baud rate matches radio setting (default: 115200) 3. Verify CI-V address is 0xA4 (IC-705 default) 4. Check USB cable integrity

USB Audio Not Working

Symptoms: CI-V control works but no audio in browser/WSJT-X

Solutions: - Install bridge dependencies: pip install 'icom-lan[bridge]' - Verify USB Audio RX/TX = Enabled in radio settings - Check audio device names with icom-lan --list-audio-devices - macOS may require microphone/audio permissions for the terminal app

Scope/Waterfall Disabled

Symptoms: enable_scope() raises error about baud rate

Solutions: - IC-705 requires 115200 baud for scope capability - Lower baud rates (19200, 9600) will trigger the guardrail - Set --baudrate 115200 or baudrate=115200 in config - Override guardrail with --allow-low-baud-scope (not recommended)

Single Receiver Errors

Symptoms: CommandError: does not support receiver=1

This is expected behavior — IC-705 has a single receiver (receiver=0 only). The dual-receiver APIs inherited from Icom7610CoreRadio will fail for receiver=1 operations. Use receiver=0 (or omit the parameter, as 0 is the default).

Capability Matrix: IC-705 vs IC-7610

Feature	IC-705	IC-7610	Notes
Receiver count	1	2	IC-705 single receiver only
Command 29 (sub RX)	❌ No	✅ Yes	IC-705 profile: command_29 not in capabilities
CI-V Address	0xA4	0x98	Auto-detected from profile
Baud rates	115200 recommended	115200 recommended	Lower rates work but disable scope
Audio codec	PCM 1ch 16bit	PCM 1ch/2ch 16bit	IC-705 same as IC-7610
Scope	Single stream	Dual stream	IC-705 single receiver = single scope
USB connector	USB-C	USB-B	Different cables
Portable	✅ Yes (QRP, battery)	❌ No (base station)	IC-705 field-optimized

Backend Comparison: LAN vs Serial

	LAN (UDP)	Serial (USB)
Connection	Ethernet/WiFi	USB cable
Setup	IP config, username, password	Plug and play
Latency	~10-50ms	~5-20ms
Field operation	Requires network	Direct connection
Audio	Opus over LAN	USB audio devices
Scope	UDP stream	USB serial stream
Production status	✅ Stable (M1-M4)	✅ Stable (M3, IC-7610 parity)

See Also

• IC-7610 USB Setup — Similar setup for base station model
• Radio Protocol — Backend abstraction details
• Troubleshooting — Common issues and solutions
• Backend Capabilities — Full capability matrix

Hardware Procurement Status

Development Hardware

IC-705 backend implementation is complete (commit 2e10765), but hardware validation is pending IC-705 procurement. Integration tests with real IC-705 hardware will be added once the radio is available.

Software validation: Contract tests with mock IC-705 profile pass (13/13 tests). Hardware validation: Blocked on IC-705 procurement (tracked in MSMA-20).