at91rm3400 ATMEL Corporation, at91rm3400 Datasheet - Page 55

• Manufacturer Part Number: at91rm3400
• Description: Atmel Advanced At91 Arm Microcontroller
• Manufacturer: ATMEL Corporation

Embedded Software Services
Overview
Service Definition
Service Structure
Structure Definition
Methods
Service Entry Point
1790A–ATARM–11/03
An embedded software service is an independent software object that drives device resources
for frequently implemented tasks. The object-oriented approach of the software provides an
easy way to access services to build applications.
An AT91 service has several purposes:
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The main features of the software services are:
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A service structure is defined in C header files.
This structure is composed of data members and pointers to functions (methods) and is similar
to a class definition. There is no protection of data access or methods access. However, some
functions can be used by the customer application or other services and so be considered as
public methods. Similarly, other functions are not invoked by them. They can be considered as
private methods. This is also valid for data.
In the service structure, pointers to functions are supposed to be initialized by default to the
standard functions. Only the default standard functions reside in ROM. Default methods can
be overloaded by custom application methods.
Methods do not declare any static variables nor invoke global variables. All methods are
invoked with a pointer to the service structure. A method can access and update service data
without restrictions.
Similarly, there is no polling in the methods. In fact, there is a method to start the functionality
(a read to give an example), a method to get the status (is the read achieved?), and a call-
back, initialized by the start method. Thus, using service, the client application carries out a
synchronous read by starting the read and polling the status, or an asynchronous read speci-
fying a callback when starting the read operation.
Each AT91 service, except for the ROM Entry Service (see Section ), defines a function
named AT91F_Open_<Service>. It is the only entry point defined for a service. Even if the
functions AT91F_Open_<Service> may be compared with object constructors, they do not
act as constructors in that they initiate the service structure but they do not allocate it. Thus
the customer application must allocate it.
Example
It gives software examples dedicated to the AT91 devices.
It can be used on several AT91 device families.
It offers an interface to the software stored in the ROM.
Compliant with ATPCS
Compliant with ANSI/ISO Standard C
Compiled in ARM/Thumb Interworking
ROM Entry Service
Tempo, Xmodem and DataFlash services
CRC and Sine tables
AT91RM3400
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