An easy way to add new multimedia functionality to your old car, based on the STM32 microcontroller and bluetooth receiver module with Apt-X/AAC support (CSR8645, RRD-305, QCC3005) which communicates via the CAN BUS protocol and completely simulates the presence and functionality of the original device.
- Support AVCTP control from steerling wheel buttons and IHU buttons;
- Reducing the volume level on revese gear shaft position;
- Optional audio amplifier blocks that can be replaced with bypass resistors;
- Availability of USB connector and GPIO connectors for connecting various sensors and modules;
Can be installed in the original place in the trunk of the car;
Project maked in STM32CubeIDE and including only user files, but system code (HAL and RTOS) can be regenerated in STM32Cube and compiled in another IDE or manualy with toolchain arm-none-eabi-gcc;
For programming MCU used ST-LINK and STM32CubeProgrammer and the board has a UART1 connector, which allows you to flash the microcontroller while it does not programmed yet using a standard USB-UART converter;
Bluetooth reciever need to bee reconfigured to use input control levels instead impulse, CCID and another settings, you can make it with FT232 USB module :howto: or with CSR programmer;
CSR programmer can use developer sowtware (ADK_CSR867x, ADK_QCC300x) and configure the chip with maximum performance, ft232 can use HeadsetConfigToolS and BlueSuite with low perfomance and the probability of errors;
The amplitude level of the output audio signal of the Bluetooth module is 3.3V with a common voltage (BIAS) of about 1.6V, while the CD changer has an amplitude of up to 5V with a common voltage of 2.5V. The module contains two differential amplifiers with a gain coefficient of 3 dB and a 5V power supply that raise the level of the audio signal to the reference level, but they are an optional component and can be replaced with zero resistance resistors R[34-37], while the AMP POWER block is not soldered and vice versa. Without amplifiers, the volume of the audio stream will be somewhat quieter than other sources, for example, radio, and will cause discomfort when switching;
Some limiting resistors can also be replaced by R0 without loss of functionality, but they are installed for maximum device reliability R[5,6,8,16,26], RN3;
The USB connector is also an optional component and is used for auxiliary purposes, for example for flashing the device in DFU mode, if you dont use it do not soldier components R[32,33], U6, E[1,2];
The microphone input block also can be skipped if you don't use hands free profile C[14,16], L2, R12;
- Standard CDC harness
827229-1aliexpress; - Standard CDC dual harness (2002+)
1-962344-12 pin1-965426-14 pin; - PCB order link or link for RU and BY;
- CSR programmer link;
- bluetooth module link;
- Electronic components (use bom file) link or ChipDip;
- ST-LINK link;
- Power save mode (sleep);
- To use Hands-Free Profile with a standard microphone, you need to lay a cable in the trunk of the car from the multimedia device;