Module bluetooth

kenwood_thd75::types

Module bluetooth 

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Bluetooth types for the TH-D75’s wireless interface.

The TH-D75 supports Bluetooth 3.0, Class 2 with two profiles (per Operating Tips §5.12 and §6.2 specifications):

  • HSP (Headset Profile): audio via BT headsets (PTT still on radio).
  • SPP (Serial Port Profile): serial data for CAT control, APRS apps, MCP-D75, and Reflector Terminal Mode.

HFP (Hands-Free Profile) and BLE (Bluetooth Low Energy) are not supported. The radio only works with HSP + SPP compatible devices.

§Hardware (per service manual §2.1.8.9, Fig.12)

The BT/GPS combo IC is IC2044, connected to the MAIN MPU (IC2005) via three interfaces:

  • HCI UART (UART2): BT control/data at 115.2 kbps (access) / 3.569 Mbps (normal), level-shifted 3.3V↔1.8V through IC2046.
  • AI2 UART (UART1): GPS NMEA data at 115.2 kbps, level-shifted through IC2036.
  • PCM audio (McASP): digital audio I2S for BT headset audio, level-shifted 3.3V↔1.8V through IC2048.

IC2044 runs on dedicated 3.3V (IC2041) and 1.8V (IC2038) regulators, with a 19.2 MHz TCXO (X2003) and 32.768 kHz RTC crystal (X2004). The MAIN MPU controls BT power via /BT_SHUTDOWN (active low reset).

Per User Manual Chapter 18:

  • Menu No. 930: Bluetooth on/off (default: Off).
  • Menu No. 931: Connect to a paired device from the device list.
  • Menu No. 932: Device search (pairing with new headset).
  • Menu No. 933: Disconnect from a Bluetooth device.
  • Menu No. 934: Pairing mode (for PC connections, 60-second countdown).
  • Menu No. 935: Device information / name (up to 19 characters).
  • Menu No. 936: Auto connect on power-on (default: On). Does not support automatic connection with a PC.

HSP audio bandwidth is limited to 4 kHz and below, so FM radio reception may sound different from speakers/earphones.

Headset volume cannot be adjusted via the radio’s [VOL] control; use the headset’s own volume control.

Transfer rate: USB up to 12 Mbps, Bluetooth up to 128 kbps. When connecting to a PC via Bluetooth 2.0 or earlier, the PIN code is 0000.

Per User Manual Chapter 28 (specifications): Bluetooth output power is -6 to +4 dBm, carrier frequency drift ±25 kHz (one slot), ±40 kHz (three/five slot).

This module is intentionally empty pending hardware capture data.