3.0 Underwriters Laboratories Requirements (UL)
The UL1998 standard was issued as a military or automotive quality/reliability document.
An important requirement is to analyze potential risks and implement a tracking process that tracks the software development cycle to take steps to address these risks. Another important requirement of UL1998 is the testing of the software development cycle throughout the process. In addition to the tests typically used for software development and post-issue testing, the standard also requires failure mode and pressure detection. When reviewing the product to verify compliance with the standard, submit the test plan and test results to demonstrate compliance with the standard.
When a microcontroller becomes a critical control element of an electrical system, it should include key architecture, hardware/software features to meet the security/detection requirements set by the regulatory agency. These requirements must meet the minimum overhead requirements of the software/hardware.
Requirements for microcontrollers include:
The device architecture MUST ensure that all instructions are executed outside of program memory; this program memory contains application software and security/diagnostic software. Any modifications to these instructions must require planned external work.
Since the software in the microcontroller program memory plays an important role in the operation of the device, the instruction set MUST contain an instruction to allow the checksum and CRC calculations to be performed during runtime.
Single-chip hardware management features such as monitors (watchdogs) and "power reduction" probes provide an extra level of protection.
The port structure should be able to detect port open and insufficient ports without special programming. Each I/O pin can be set to both the output and input addresses to provide efficient and fast diagnostics.
The benefits of connecting automotive electronics to a local Bluetooth network are becoming increasingly apparent and quickly become a standard feature favored by customers with intent to purchase. However, the automotive industry has special requirements for reliability and compatibility that exceed normal home and office standards.
4.0 Automotive Quality / Safety Requirements
Existing non-Bluetooth microcontrollers are shipping in large quantities to supply safety critical automotive applications that require high levels of safety and quality.
In addition, automakers have proposed some quality/reliability requirements for microcontroller suppliers. These important areas include:
Scan Detection - Ensures that all transistors are functioning properly (up to 99% or more).
Electrical Stress Detection - Detects equipment at voltages above the specified maximum operating voltage but below the device breakdown voltage.
Built-in self-test (BIST) - reverse the encoding
Repeat tests for different single-chip functional tests and customer-specific tests.
Maverick component inspection - a device that eliminates distortion. Therefore, the performance of each device should be consistent when shipped.
5.0 Add Bluetooth connectivity in automotive applications
5.1 Bluetooth software
The Bluetooth specification defines the power management modes that may be involved when the device is not communicating effectively. These modes can be used to implement various power reduction strategies such as reducing or suspending the CPU clock, turning off external devices, or turning off the radio transceiver. These mechanisms reduce internal switching currents with the effect of reducing power consumption and reducing EMI. The power consumption of Bluetooth wireless devices is a major component of the overall power consumption of the Bluetooth chipset. The power management mode can also be used to keep the wireless device in full power state only when needed. (The 802.11b system is somewhat different from the one in which the wireless device in the system is always powered up, close to the power consumption of the connected LAN.)
5.2 Bluetooth hardware
Qualified microcontrollers in automotive applications now offer integrated Bluetooth support (referred to as Bluetooth baseband hardware and protocol stack software). This provides the benefits of low risk, fast track for developing products that meet automotive industry standards.
5.3 Built-in RF detection mode
The Bluetooth protocol stack provides built-in detection mode for RF detection. There are two ways to enter Bluetooth detection mode:
Static Method - The Bluetooth core is initialized when the Detect Mode option is enabled, so it has entered the detection mode at startup.
Dynamic Method - The application software sends a command that causes the Bluetooth stack to enter detection mode. The final application can trigger this mode. For example, the application can read a switch or button.
5.4 Testing / Identification
To help embedded Bluetooth products pass authentication, vendors of Bluetooth solutions are expected to offer a full set of embedded Bluetooth stacks running on baseband processors and Bluetooth wireless devices as pre-test/pre-authentication components.
To qualify, the component must be integrated into the final product or reference design and then passed through a minimal set of tests (as described in Bluetooth's Qualification Program Reference Document).
In addition, this reference design board needs to be modified to meet FCC and automotive EMC/EMS requirements. This means that the developer of the final product does not have to perform all of the inspection processes, and pre-test components and final product identification typically perform such inspections. Identifying/detecting individual Bluetooth components and incorporating reference designs for these components is helpful to product developers, providing them with a reliable starting point for product development and qualification.
The benefits of connecting automotive electronics to a local Bluetooth network are becoming increasingly apparent and quickly become a standard feature favored by customers with intent to purchase. However, the automotive industry has special requirements for reliability and compatibility that exceed normal home and office standards.
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