AUTOSAR (10) - Memory stack

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Memory stack

Memory stack is a collection of components in AUTOSAR which offer standardized access to internal/external memory (non volatile memory). The memory stack modules provide services to store and maintain non-volatile (NV) data in an automotive environment. The NVRAM Manager module manages all data requests from different application tasks to access the data in the NV memory.

The NVRAM Manager works with the Memory Abstraction Interface (MemIf) module to access the EEPROM Abstraction (Ea) and Flash EEPROM Emulation (Fee). This means that the NVRAM Manager is independent of the hardware memory and will support different types of NV memory devices. In addition, the Crc module provides routines to calculate a checksum that can be stored together with the data in NV memory.

Memory stack

NVRAM Manager

It is responsible for the management of non volatile data (read/write from different memory drivers). Provides services to ensure the data storage and maintenance of NV data synchronous/asynchronous services for the management and the maintenance of NV data.

MemIf

Abstraction for the underlying memory abstraction devices for the upper layers to access the devices as a uniform linear memory addressing space.

Fee - Flash EEPROM Emulation
  • provides a mechanism to spread the write access such that the FLASH is not overstressed
  • manage for each block the information, whether this block is consistent or not

Ea - EEPROM Abstraction
  • provides a mechanism to spread the write access such that the EEPROM is not overstressed
  • manage for each block the information, whether this block is consistent or not

Memory Hardware Abstraction 

Abstracts from the location of peripheral memory devices (on-chip or on-board) and the ECU hardware layout.

Memory Drivers 

Drivers for on-chip memory devices and memory mapped external memory devices (Flash, EEPROM).   

Drivers for on-chip memory devices and memory mapped external memory devices (Flash, EEPROM).

NVRAM Manager - Basic storage objects

  • Is the smallest entity of a “NVRAM block”.
  •  Several “Basic Storage Objects” can be used to build a NVRAM Block.
  •  Can reside in different memory locations (RAM/ROM/NV memory)

NVRAM Manager - Basic storage objects

 NV block
    Is a basic storage object and represents a memory area consisting of NV user data and (optionally) a CRC value and (optionally) a NV block header.   

RAM block

  •     Is a basic storage object and represents an area in RAM consisting of user data and (optionally) a CRC value.
  •     Can be permanent or temporarily assigned 
  •     The data area of a RAM block shall be accessible from NVRAM Manager and from the application side

ROM block
    Is a basic storage object, resides in the ROM (FLASH) and is used to provide default data in case of an empty or damaged NV block

 

ROM block Is a basic storage object, resides in the ROM (FLASH) and is used to provide default data in case of an empty or damaged NV block

Interaction overview 

Interaction overview

Functional interface interaction overview

This specification describes the functionality, API and configuration of the AUTOSAR Basic Software Module “Memory Abstraction Interface” (MemIf). This module allows the NVRAM manager to access several memory abstraction modules (FEE or EA modules). 
This specification describes the functionality, API and configuration of the AUTOSAR Basic Software Module “Memory Abstraction Interface” (MemIf). This module allows the NVRAM manager to access several memory abstraction modules (FEE or EA modules).

Documentation

AUTOSAR articles (for articles written in Romanian please select your language from right part of webpage)

 Thank you for attention !

For questions please contact me on email: simedruflorin@automatic-house.ro. 

Have a nice day ! 

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