Image Processing Reference
In-Depth Information
provides a service for comparing a data block in the EEPROM with a data block in the memory
(e.g., RAM).
Flash EEPROM emulation
(
Fee
): he Flash EEPROM Emulation module “emulates EEPROM func-
tionality” using the services provided by Flash Driver module. By making use of multiple flash sectors
and smart copying of the data between these sectors, the
Fee
simulates an EEPROM-like behavior,
i.e., the possibility to perform program/erase operations on subsector granularity.
EEPROM abstraction
(
Ea
): The EEPROM Abstraction module “provides uniform mechanisms to
access the ECU's internal and external EEPROM devices.” It abstracts from the location of peripheral
EEPROM devices (including their connection to the microcontroller), the ECU hardware layout, and
the number of EEPROM devices.
Memory abstraction interface
(
MemIf
): The Memory Abstraction Interface module allows the
Nonvolatile RAM Manager module (see below) to “access several memory abstraction modules
(
Fee
or
Ea
modules) in a uniform way.” Hereby, the
MemIf
abstracts from the number of under-
lying
Fee
or
Ea
modules providing a runtime translation of each block access initiated by the
Nonvolatile RAM manager module to select the corresponding driver functions which are unique
for all configured EEPROM or flash EEPROM storage devices.
Nonvolatile RAM manager
(
NvM
): The Nonvolatile RAM manager module provides services to
“ensure the data storage and maintenance of nonvolatile data” according to their individual require-
ments in an automotive environment, namely, synchronous as well as asynchronous services for the
initialization, the reading, the writing, and the control of nonvolatile data. The
NvM
operates on
a block basis, where the following types of blocks are distinguished: For “native blocks” the
NvM
provides a “RAM mirror,” which contains a copy of the data stored in the nonvolatile memory block.
This RAM mirror is initialized with the data from the nonvolatile block upon ECU power-up. Upon
ECU shutdown, the data from the RAM mirror is flushed to the corresponding nonvolatile memory
block. Additionally, the
NvM
provides API services which can force the transfer of a memory block
from nonvolatile memory into the corresponding RAM mirror and vice versa. In addition to the
facilities of native blocks “redundant blocks” provide enhanced fault tolerance, reliability, and avail-
ability. Due to replication of the redundant block in nonvolatile memory, the resilience against data
corruption is increased.
RAM test
(
RamTst
): he RAM Test module performs “functional tests of the ECU's internal RAM
cells.” “Complete” tests are performed upon ECU start-up and shutdown as well as on request by
special diagnostic commands. During operation “partial test” are performed in a periodic manner
(e.g., block by block or cell by cell). For both types of tests several RAM test algorithms, which have
been chosen according to the IEC standard, are available. Depending on the algorithms' diag-
nostic coverage rate, the algorithms are divided into the following categories: Group (low) with a
diagnostic coverage rate smaller than %, group (medium) exhibiting a diagnostic coverage rate
of %-%, and group (high) with a diagnostic coverage rate of %-%.
18.7.2.3 I/O Substack
The I/O substack contains a group of modules that facilitate handling of the ECU's I/O capabilities.
The structure of the I/O substack is depicted in Figure ..
In the following, the different modules of the I/O substack are described in detail.
Interrupt capture unit driver
(
Icu
): he interrupt capture unit (ICU) Driver is a “module using the
ICU hardware” to implement services like signal edge notification, controlling of wake-up interrupts,
periodic signal time measurement, edge time stamping (usable for the acquisition of non-periodic
signals), and edge counting.
