Microchip logo
  • All
  • Products
  • Documents
  • Applications Notes

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.

For additional information about Microchip’s functional safety enabled products and supporting documentation, please visit: www.microchip.com/functional-safety

MPLAB® XC Compiler Functional Safety Manual

Register to download the MPLAB® XC Compiler Functional Safety Manual and learn more about suggested safety measures for applications up to ISO 26262 ASIL D.

Send me the Functional Safety Manual

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-qualified 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) Error Detection and Correction
+
FeaturedsPIC33CdsPIC33EPIC24FFault PreventionSelf DiagnosticSystem DiagnosticFault Mitigation
CRC module / Cyclical Redundancy Check (CRC)*   
Flash Error Detection and Correction (ECC)   
Read / Write Memory Protection    
Boot Segment Protection    
Dual Partition Program Memory   
Illegal Opcode Detect   
Load Once Per Reset Config Register    
RAM BIST--   
Self-Readable Flash Memory   
Definitions:
Fault Prevention - Silicon feature that prevents damage, unintended configuration changes or invalid operation
Self-Diagnostic - Silicon/software feature that identifies if the silicon is working as it should be
System Diagnostic - Silicon/software feature that identifies if the system is working as it should be
Fault Mitigation - Silicon feature that can be used by the system to transition to a safe state after a fault is detected
Legend:
● Available in all devices
○ Available in some devices
- Not Available
System Reset, Detect and Manage
+
FeaturedsPIC33CdsPIC33EPIC24FFault PreventionSelf DiagnosticSystem DiagnosticFault Mitigation
Power-on Reset (POR)  
Brown-out Reset (BOR)  
Windowed Watchdog Timer
Dual Watch-dog

Std. WDT
 
Deadman Timer- 
Configuration Mismatch Reset  
High/Low Voltage Detect (HLVD)--   
High-Voltage Detect (HVD)--  
PWM Fault Management   
PWM Lock-   
UART Internal Loopback

   
Reset Trace   
Asynchronous Master Clear Reset (MCLR)   
CAN Port Loopback Mode

-
   
ICSP Write Inhibit-   
On-chip Regulator for CPU   
Capacitor-less Regulator--   
Definitions:
Fault Prevention - Silicon feature that prevents damage, unintended configuration changes or invalid operation
Self-Diagnostic - Silicon/software feature that identifies if the silicon is working as it should be
System Diagnostic - Silicon/software feature that identifies if the system is working as it should be
Fault Mitigation - Silicon feature that can be used by the system to transition to a safe state after a fault is detected
Legend:
● Available in all devices
○ Available in some devices
- Not Available
GPIO ESD Protection / PPS
+
FeaturedsPIC33CdsPIC33EPIC24FFault PreventionSelf DiagnosticSystem DiagnosticFault Mitigation
ESD Protection   
Peripheral Pin Select  
I/O Port Readback  
Virtual Pins--   
Definitions:
Fault Prevention - Silicon feature that prevents damage, unintended configuration changes or invalid operation
Self-Diagnostic - Silicon/software feature that identifies if the silicon is working as it should be
System Diagnostic - Silicon/software feature that identifies if the system is working as it should be
Fault Mitigation - Silicon feature that can be used by the system to transition to a safe state after a fault is detected
Legend:
● Available in all devices
○ Available in some devices
- Not Available
Clocking Systems Backup Oscillators / Monitors
+
FeaturedsPIC33CdsPIC33EPIC24FFault PreventionSelf DiagnosticSystem DiagnosticFault Mitigation
Redundant Oscillator
BFRC
   
Lockable Clock (OSCCON)   
Fail Safe Clock Monitor 
Windowed Watchdog Timer
Dual Watchdog

Std. WDT
 
Two-speed Start-up 
Definitions:
Fault Prevention - Silicon feature that prevents damage, unintended configuration changes or invalid operation
Self-Diagnostic - Silicon/software feature that identifies if the silicon is working as it should be
System Diagnostic - Silicon/software feature that identifies if the system is working as it should be
Fault Mitigation - Silicon feature that can be used by the system to transition to a safe state after a fault is detected
Legend:
● Available in all devices
○ Available in some devices
- Not Available
CPU Trap Instructions / Fault Detection
+
FeaturedsPIC33CdsPIC33EPIC24FFault PreventionSelf DiagnosticSystem DiagnosticFault Mitigation
Error Trap Monitors  
Definitions:
Fault Prevention - Silicon feature that prevents damage, unintended configuration changes or invalid operation
Self-Diagnostic - Silicon/software feature that identifies if the silicon is working as it should be
System Diagnostic - Silicon/software feature that identifies if the system is working as it should be
Fault Mitigation - Silicon feature that can be used by the system to transition to a safe state after a fault is detected
Legend:
● Available in all devices
○ Available in some devices
- Not Available
Analog Internal Vref and Sample / Hold
+
FeaturedsPIC33CdsPIC33EPIC24FFault PreventionSelf DiagnosticSystem DiagnosticFault Mitigation
Internal Vref  
Multiple Sample and Hold   
Charge Time Measurement Unit (CTMU)-  
Definitions:
Fault Prevention - Silicon feature that prevents damage, unintended configuration changes or invalid operation
Self-Diagnostic - Silicon/software feature that identifies if the silicon is working as it should be
System Diagnostic - Silicon/software feature that identifies if the system is working as it should be
Fault Mitigation - Silicon feature that can be used by the system to transition to a safe state after a fault is detected
Legend:
● Available in all devices
○ Available in some devices
- Not Available
Class B Safety Software
+
FeaturedsPIC33CdsPIC33EPIC24FFault PreventionSelf DiagnosticSystem DiagnosticFault Mitigation
RAM Variable Memory Test   
Frequency Detect  
Program Counter Stuck-at-Faults   
CPU Register Test   
Definitions:
Fault Prevention - Silicon feature that prevents damage, unintended configuration changes or invalid operation
Self-Diagnostic - Silicon/software feature that identifies if the silicon is working as it should be
System Diagnostic - Silicon/software feature that identifies if the system is working as it should be
Fault Mitigation - Silicon feature that can be used by the system to transition to a safe state after a fault is detected
Legend:
● Available in all devices
○ Available in some devices
- Not Available
Other Features
+
FeaturedsPIC33CdsPIC33EPIC24FFault PreventionSelf DiagnosticSystem DiagnosticFault Mitigation
MPLAB® XC CompilersC-Compilers ASIL-D Qualified per ISO 26262
MCAL Drivers for Autosar   
LDRA Compliance Management Tool Suite Support (3rd party) 
Definitions:
Fault Prevention - Silicon feature that prevents damage, unintended configuration changes or invalid operation
Self-Diagnostic - Silicon/software feature that identifies if the silicon is working as it should be
System Diagnostic - Silicon/software feature that identifies if the system is working as it should be
Fault Mitigation - Silicon feature that can be used by the system to transition to a safe state after a fault is detected
Legend:
● Available in all devices
○ Available in some devices
- Not Available

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