要对开源软件保持警惕，谨慎使用
既然开源软件的版权受控，不是无条件使用，所以它具备一定的风险并非空穴来风，除上文提到的开源转闭源的商业风险外，还存在政治因素风险。
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BlueZ
BlueZ-Official Linux Bluetooth protocol stack
Android 4.2之前，Google一直使用的是Linux官方蓝牙协议栈BlueZ。BlueZ实际上是由高通公司在2001年5月基于GPL协议发布的一个开源项目，做为Linux 2.4.6内核的官方蓝牙协议栈。随着Android设备的流行，BlueZ也得到了极大的完善和扩展。例如Android 4.1中BlueZ的版本升级为4.93，它支持蓝牙核心规范4.0，并实现了绝大部分的Profiles。
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AC781x Automotive Microcontroller
- Overview：
- The AC781x product serials is MCU of automotive grade, complies with the AEC-Q100 specification, and is suitable for automotive electronics and high reliability industrial applications.Typical applications cover BCM, T-BOX, BLDC motor control, industrial control, AC charging piles, etc.
The AC781x device family is based on ARM Cortex®-M3 core, running up to 100MHz，up to 256KB Flash memory，supply voltage ranges from 2.7 to 5.5V, excellent EMC/ESD capability to be suit for harsher environment.
- Features：
- - ARM Cortex®-M3 core,100MHz, single cycle 32x32 multiplier
- Support up to 256KB embedded Flash memory
- Support up to 64KB RAM
- Support 2*CAN 2.0B
- Support 1*LIN 2.1, 1*URAT LIN
- Support 2*SPI
- Support up to 6*UART
- Support 2*I2C
- 2.7-5.5V power supply
- Temperature range: -40 to 125 °C
CSR8635/CSR8615 Class2 Stereo ROM Module Electrical characteristic
General Electrical Specification
Absolute Maximum Ratings:
| Ratings | Min. | Max. |
| Storage Temperature | -40 ℃ | +85 ℃ |
| Supply Voltage (VCHG) | -0.4V | 5.75V |
| Supply Voltage (VREG_ENABLE,VBAT_SENSE) | -0.4V | 4.2V |
| Supply Voltage (LED[2:0]) | -0.4V | 4.4V |
| Supply Voltage (PIO_POWER) | -0.4V | 3.6V |
Recommended Operating Condition:
| Operating Temperature range | -20 ℃ | +75 ℃ |
| Supply Voltage (VBAT) | 2.7V | 4.25V |
| Supply Voltage (VCHG) | 4.75V / 3.10 V | 5.25V |
| Supply Voltage (VREG_ENABLE,VBAT_SENSE) | 0V | 4.2V |
| Supply Voltage (LED[2:0]) | 1.10V | 4.25V |
| Supply Voltage (PIO_POWER)* | 1.7V | 3.6V |
1.8V Switch-mode Regulator :