IEC60730 is the common software safety requirement standard mainly for household appliances. This basically applies to the automation control products where there is control logic involved and safety is the major concern. IEC60730 classifies products into 3 classes: class A, Class B, Class C. Class C is the more stringent of the classes and this focuses on prevention of any catastrophic events due to control circuit failure. For example, any system which can cause fire break out in case of failure falls under Class C. Both hardware and software designs must incorporate safety features into their respective domains. The standard is defined for controls below 690V and rated current below 63V.
When we talk about hardware/software, the following are the common scenarios:
1. The built-in-self test (BIT) need to be executed periodically to ensure proper health of on-board components.
2. Software developed so that any malfunction to be monitored using resources like watchdog timer. The common scenarios we come across are the microcontroller execution halting due to improper interrupt handling mechanism, clock failures, memory overflow, etc.,
3. Protection for the flash memory using the inbuilt CRC engine
4. Communication using external interfaces to be monitored to eliminate errors. Error Detection, Handling are very critical
5. The external hardware must have feedback mechanism to monitor the health. Micro controller monitors the health of such signals and takes critical decisions.
6. Redundancy is one of the good options to have when that particular section failure causes hazardous situations.
7. Testing the RAM for failures is also important
8. When a diagnosis test sees a failure, the software must be written in such a way that the system must halt in safe mode.
9. The internal registers are to be monitored using static memory test
The firmware must implement special routines for such diagnostic features implementation. Also, during compliance, test routines specific to these checks are to be written by developer. these all need to be accommodated in the firmware life cycle to avoid any last minute developments.
Most of the microcontroller vendors provide solutions for IEC60730. For example, MSP430-IEC60730-SW-PACKAGE for the MSP430 controllers from Texas Instruments and software package by NXP for the Kinetics V series family of microcontrollers. Choosing these microcontrollers help to ease the pain of compliance at a later step. Before using any software package from vendor verify the class up to which the software package supports.
]]>
0 Comments