Expand description
Serial port transport for USB CDC ACM and Bluetooth SPP connections.
The MAIN MPU (IC2005, OMAP-L138) communicates with the PC via USB
Type-C (J1) using a Mentor Graphics MUSB USB 2.0 OTG controller
with MatrixQuest CDC ACM stack. VID 0x2166 (JVCKENWOOD), PID
0x9023. The USB interface presents as CDC ACM (class 0x02,
subclass 0x02, protocol 0x01 V.25ter) with 3 endpoints: interrupt
IN, bulk OUT, bulk IN. USB D+/D- run at Full Speed (12 Mbps).
USB uses 115200 baud (CDC ACM ignores line coding — per the Kenwood Operating Tips §5.13, “configuring the baud rate is unnecessary, selecting randomly will suffice” since it’s a virtual COM port). USB also provides audio output (48 kHz, 16-bit, monaural — per §5.13.2).
Bluetooth SPP runs through BT/GPS IC2044 → level-shift IC2046 → MAIN MPU UART2. Requires 9600 baud with RTS/CTS hardware flow control. The D75 supports Bluetooth 3.0 Class 2 with HSP + SPP profiles only (no BLE, no HFP). Per §5.12, “configuration of the baud rate is not necessary” for BT serial either, but we set 9600 explicitly for compatibility.
The same VID/PID (2166:9023) is used in both normal operation and
firmware update mode (PTT+1 at power-on), though update mode uses
the bootloader’s simpler USB implementation rather than MatrixQuest.
open auto-detects BT ports and applies the
correct settings.
Structs§
- Serial
Transport - Serial port transport for USB CDC ACM and Bluetooth SPP connections.