Home
11 SRAM - March C-Minus Algorithm
This module contains functional safety diagnostics APIs for SRAM March-C Minus.
11.1 Defines
11.1.1 SRAM_DATA_REGION_LEN

Introduction
This document contains API documentation for the diagnostic tests included MPLAB® Code Configurator AVR® IEC60730 Class B Diagnostic Library.
1 Software Requirements
2 Clock Frequency Test
This module contains functional safety diagnostics APIs for Clock Frequency test.
3 CPU Program Counter
This module contains functional safety diagnostics APIs for CPU Program counter test.
4 CPU Registers
This module contains functional safety diagnostics APIs for CPU Registers.
5 EEPROM - 16-bit CRC
This module contains APIs to calculate, store and validate 16-bit CCITT CRC for a given EEPROM region.
6 EEPROM - 32-bit CRC
This module contains APIs to calculate, store and validate 32-bit CCITT CRC for a given EEPROM region.
7 FLASH - 16-bit CRC
This module contains APIs to calculate, store and validate 16-bit CCITT CRC for a given FLASH region.
8 FLASH - 32-bit CRC
This module contains APIs to calculate, store and validate 32-bit CCITT CRC for a given FLASH region.
9 Interrupt Frequency Test
This module contains functional safety diagnostics API for Interrupt Frequency Test.
10 SRAM - Checkerboard Algorithm
This module contains functional safety diagnostics APIs for SRAM Checkerboard Test.
11 SRAM - March C-Minus Algorithm
This module contains functional safety diagnostics APIs for SRAM March-C Minus.
- 11.1 Defines
- 11.2 Functions
12 Simple Watchdog Timer
This module contains functional safety diagnostics APIs for WatchDog Timer Test.
13 Windowed Watchdog Timer
This module contains functional safety diagnostics APIs for WatchDog Timer Test.
14 File List
Here is a list of all documented files with brief descriptions
15 Class List
Here is a list of all documented files with brief descriptions

11.1.1 SRAM_DATA_REGION_LEN

#define SRAM_DATA_REGION_LEN (INTERNAL_SRAM_SIZE)

To decrease the size of the SRAM available for the application, in order to reduce worst case execution time (WCET) of the SRAM March diagnostic test, go to Project Properties -> XC8 Linker -> Option categories: Additional options and insert the following linker option in the additional linker options field:

-Wl,defsym=__DATA_REGION_LENGTH__="insert reduced SRAM size value"

Moreover, the start of the stack must additionally be configured to point at the new end address of the SRAM used by the application by using the following linker option (this will take effect after .init0 but before main()):

-Wl,defsym=__stack="insert new end address"

Finally, the SRAM_DATA_REGION_LEN macro must be set to the new reduced SRAM size value.

As an example, to reduce the SRAM size of an AVR128DA48 from default 0x4000 (derived from the the INTERNAL_SRAM_SIZE macro value in the ioavr128da48.h) to 0x2000, the new end address will be:

INTERNAL_SRAM_START(= 0x4000) + 0x2000 - 1 = 0x5FFF

Thus, the following linker option should be set:

-Wl,defsym=__DATA_REGION_LENGTH__=0x2000 -Wl,defsym=__stack=0x5FFF

and the SRAM_DATA_REGION_LEN macro should be updated to:

SRAM_DATA_REGION_LEN 0x2000U