Standardized System Software for Automotive Applications - Networked Embedded Systems - page 435

I/O HW abstraction

Icu Port Pwm Dio Adc

Hardware

FIGURE . AUTOSAR—I/O substack.

Port driver ( Port ): The Port Driver module provides the service for “initializing the whole port
structure” of the microcontroller, allowing for the configuration of different functionalities for each
port and port pin (e.g., analog digital conversion (ADC), digital I/O (DIO), etc.). Hereby, the port
pin direction (I/O), the initial level of the port pin, and the fact whether the port pin direction is
modifiable during run-time are part of this configuration. Other I/O drivers (e.g., Dio , Adc ,etc.)
rely on the configuration performed by the Port Driver.
Pulse width modulation ( Pwm ) driver : he PWM Driver module provides functions to “initialize and
control the hardware PMW unit” of the microcontroller. he Pwm module thus allows for the gener-
ation of pulses with variable pulse width by facilitating the selection of the duty cycle and the signal
period time. he Pwm module supports multiple PWM channels, where each channel is linked to a
hardware PWM unit which belongs to the microcontroller.
Digital I/O driver ( Dio ): The DIO Driver provides services for “reading from and writing to DIO
channels” (i.e., port pins), DIO ports, and groups of DIO channels. Hereby, the Dio modules work
on pins and ports which have been properly configured by the Port Driver for this purpose.
Analog/digital converter ( Adc ) driver : he ADC Driver module “initializes and controls the internal
ADC unit(s)” of the microcontroller. The module provides services to start and stop an analog to
digital conversion respectively to enable and disable the trigger source for a conversion. Furthermore,
the module provides services to enable and disable a notification mechanism and routines to query
status and result of a conversion. he Adc module works on so-called ADC channel groups. An ADC
channel group combines an ADC channel (i.e., an analog input pin), the needed ADC circuitry itself,
and a conversion result register into an entity that can be individually controlled and accessed via the
Adc module.
I/O hardware abstraction : The I/O Hardware Abstraction module provides a signal-based interface
to internal and external I/O devices of an ECU. Hereby, the module abstracts from whether a cer-
tain I/O device is an MCU internal device, or whether a device is externally connected to the MCU,
by performing static normalization/inversion of values according to their physical representation
attheinputs/outputsoftheECUhardware(i.e.,staticinluences,likevoltagedivisionorhardware
inversion, on the path between the I/O device and the MCU port pin are compensated).

18.7.2.4 System Services Substack

The system services substack contains a group of modules that can be used by modules of all
AUTOSAR layers. Examples are real-time-operating system, error handler, and library functions
(like CRC and interpolation functions). he structure of the system services substack (excluding the
library functions) is depicted in Figure ..
In the following the different modules of the system services substack are described in detail.

Operating system ( Os ): he AUTOSAR-operating system provides “real-time-operating system ser-
vices” to both the other system software modules and to the application software components of