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Functional Safety

Applications such as appliances, medical devices and vehicles have increased reliance on electronics for efficient control and enhanced user features. These applications require safe and reliable operation to protect end-user well-being. Most of the time electrical systems operate as intended, but on occasion, software or hardware can operate differently than it was intended to by the designer. Safety specifications, such as IEC 60335, are used to ensure manufacturers have designed their products to operate safely. The portion of this specification that applies to electronic controls in appliances is called IEC 60730. 

Several hardware peripherals and functions have been integrated into PIC24 and dsPIC33 devices to help increase the reliability and redundancy for these applications. Memory includes error correction capability and integrity checks. The CPU includes trap instructions and back-up oscillators. System-level monitors are included for POR, BOR, WWDT, Deadman Timer and many other fault detection and reliability features. 

Microchip has developed a library of low-level software routines and hardware peripherals that simplify meeting IEC 60730 requirements for Class B Safety. Application Note AN1778 describes the Application Programming Interface (API) functions that are available in the Class B Safety Software Library and how to incorporate them in your project.

MPLAB® XC Compiler Functional Safety Manual

Learn more about the Functional Safety manual for applications up to ISO 26262 and ASIL-D.

Hardware Modules Supported

  • Memory with error detection and correction
  • CPU with trap instructions and fault detection
  • Clocking systems including backup oscillators
  • GPIO with ESD protection Analog systems
  • System monitors: POR, BOR, WWDT, Deadman Timer, hardware limit timer and voltage detection

Software Library Routines:

  • Detect the occurrence of faults in a single-channel CPU
  • Developed in accordance with IEC 60730 to support Class B certification process
  • Routines directly integrate into MCU applications to test and verify the critical functionalities without affecting the end application

Whole Ecosystem

  • ISO26262-certified compiler
  • FMEDA report*
  • MPLAB X IDE MISRA plug-in
  • Liverpool Data Research Associates (LDRA) Tool Suite for functional safety compliance
  • Affiliation with certification bodies (VDE, UL)

* Contact your local Sales office for details

Functional Safety Relevant Features – 16-bit PIC® MCUs and dsPIC® DSCs

Dedicated peripherals and functions have been integrated into the PIC24 and dsPIC33 devices to help increase the reliability and monitoring for safety-critical applications. Together these features help ensure end applications operate as intended, with safe shut down if any exception or issue arises.

Memory (Flash/RAM)
+
  • CRC module / cyclical redundancy*
  • Flash Error Detection and Correction (ECC)
  • Read / write protection
  • Boot segment protection
  • Dual partition Flash
  • Illegal opcode detect
  • RAM variable memory test*
  • Load once per reset configuration register
  • Self-Readable Flash Memory
System
+
  • Power-on and brown-out resets
  • Windowed watchdog and deadman timers
  • Configuration mismatch reset
  • High / Low-Voltage Detect (HLVD)
  • High-Voltage Detect (HVD)
  • PWM fault management (overcurrent / voltage)
  • External PWM lock management (reset)
  • Unique ID
  • CAN/UART internal loopback
  • Reset trace
  • Asynchronous Master Clear Reset (MCLR)
  • CAN Port Loopback Mode
GPIO
+
  • ESD protection
  • Boundary scan
  • Peripheral pin select
  • Self-readable output pins
Clocking Systems
+
  • Redundant oscillator
  • Lockable clock (OSCCON)
  • Fail safe clock monitor
  • Frequency detect*
  • Windowed watchdog and deadman timer
CPU
+
  • Error trap monitor (oscillator, stack, address, math)
  • Program counter stuck-at fault*
  • CPU register test
Analog
+
  • Internal VREF
  • Multiple sample and hold
  • Charge Time Measurement Unit (CTMU)
Other Features
+
  • MCAL drivers for Autosar
  • C-Compiler ASIL-D Qualified per ISO-26262
  • LDRA Compliance Management Tool Suite Support

* Class B Safety Software

Components Covered by Class B Safety Software Library

The library includes routines to detect for faults in the CPU registers, program counter interrupts clocking and memory. This library was developed in accordance with IEC 60730 to support Class B certification process. The software routines are integrated into the final application to test and verify the critical functionalities without affecting the end application.

 MCU Circuit ComponentFault/Error
1CPU RegistersStuck
2Program CounterStuck
3Interrupt handling and executionNo interrupts or too many interrupts
4Clock FrequencyClock failure or incorrect frequency
5Memory testing (Flash/EEPROM)All single bit faults
6Memory testing (RAM)DC fault
Functional Safety Block Diagram
 
TypeDownloadSHA-1 Fingerprint
Software LibraryMCU16 ClassB Ver2 2.40b3f2ff9ede7bfe9e817b2539fc5c6388396c451d
 16-bit Self-test Library 
DocumentationClass B Safety Software Library for PIC® MCUs and dsPIC® DSCs (AN1778)b77f6dbd8a1184fbab6777a81185785b8a4ac5a3
VDE CertificationMCU16 VDE Test Certificate 
UL CompliancePIC24 UL Certificate of Compliance 

16-bit Video Channel