RL78/F23, F24: Safety Function
■This application note describes the safety functions implemented on the RL78/F23, RL78/F24 microcontrollers (MCUs).
●Target device
■RL78/F23, RL78/F24
●Overview of the Safety Functions
■To detect any errors and failures with the built-in self-test function, the RL78/F23, RL78/F24 MCUs have the
following safety functions.
▲CRC (cyclic redundancy check) operation functions (High-speed CRC operation & general-purpose CRC operation)
◆High-speed CRC operation: This check is executed on the entire code flash memory area after stopping the CPU (making the CPU transition to HALT mode).
◆General-purpose CRC operation: The general-purpose CRC can be used in the code flash memory area. Also, it can be used for multi-purpose data check such as serial communication.
▲Internal RAM-ECC function
◆This function detects and corrects data corruption (bit errors) during a read access to the internal RAM and notifies the error detected/corrected by generating an interrupt.
▲CAN RAM-ECC function
◆This function detects and corrects data corruption (bit errors) during a read and write access to the CAN RAM and notifies the error detected/corrected by generating an interrupt.
▲Code Flash-ECC function
◆This function detects and corrects data corruption (bit errors) during a read access to the code flash memory and notifies the error detected/corrected by generating an interrupt.
▲CPU stack pointer monitor function
◆This function detects an overflow and underflow of the stack pointer (SP) and generates an interrupt in response.
▲Clock monitor function
◆This function detects an oscillation stop of the main system clock (f MAIN ) and main/PLL selection clock (f MP) using the low-speed on-chip oscillation clock (f IL) and accordingly generates a reset signal or interrupt.
▲RAM guard function
◆This function protects data in RAM that is to be guarded from any erroneous writing when a CPU runaway etc., occurs.
▲SFR guard function
◆This function protects the SFRs (special function registers for port functions, interrupts, clock control, and voltage detector control) that is to be guarded from any erroneous writing when a CPU runaway or any problem occurs.
▲Invalid memory access detection function
◆This function detects any invalid access to the memory area when a CPU runaway or any problem occurs and generates a reset signal.
▲Frequency detection function
◆The function detects whether or not the clock is operating on an abnormal frequency by comparing the high-speed on-chip oscillator clock (f IH), external X1 oscillation clock (f MX), or PLL clock (f PLL ) with the low-speed on-chip oscillator clock (f IL).
▲A/D test function
◆This function supports a self-check of A/D conversion, and the build-in pre-charge and dis-charge function to be able to assist disconnection detection of the wire which is connected to analog inputs.
▲Digital output signal level detection function for I/O ports
◆This function detects any output abnormality by reading the digital output level (high or low) of the pin when the port is set to output mode.
▲Watchdog timer function
◆This function detects an inadvertent program loop, and assert internal reset signal to CPU.
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Application note & Design Guide |
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Please see the document for details |
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English Chinese Chinese and English Japanese |
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2022.09.30 |
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Rev.1.00 |
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R01AN6624EJ0100 |
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2.9 MB |
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