Mobile phone Development Combat 1-Mobile phone introduction

The handset is essentially a real-time embedded system.

Embedded system is the application-centric and computer-based, and software and hardware can be cut, can meet the application system to function, reliability, cost, volume and power consumption, such as the strict requirements of the professional computer system. It is usually composed of embedded processor, embedded peripheral device, embedded operating system and embedded application software.

Embedded application software development uses a cross-development environment.

A cross-development environment is an environment that implements, compiles, links, and debugs application code. Unlike the environment in which the application is run, it is scattered across host and target environments with communication connections.

The cross-development hardware environment includes the host and the target machine.

Host is a general-purpose computer that can be a PC or a workstation. It communicates with the target via a serial port or network connection.

Target can be the actual operating environment of embedded software application software, or it can be a simulation system which can replace the actual environment.

Real-time Systems (RealTime system) are systems that can perform system functions and respond to external or internal events in a synchronous or asynchronous time within a specified or determined time.

The response time (Response time) is when the computer recognizes an external event to respond.

The real-time system can be divided into 3 types depending on response time:

Weak real-time system-response time can be 10 seconds or longer;

General real-time system-response time can be in the order of seconds, such as mobile phone system;

Strong real-time system-response time in milliseconds or subtle order of magnitude;

In an RTOS, a task is the basic unit of owning resources and dispatching independently. Similar to a thread in the operating system, it is a running process of an infinite loop program with independent functionality, with dynamic, parallel, and asynchronous independence.

Dynamic means that the state of the task is constantly changing. Parallelism means that multiple tasks in a system are parallel on the macro level. Asynchronous independence refers to the task is the basic unit of independent operation of the system, is also the core allocation and dispatch of the basic unit, cabinet tasks run independently of each other. A task is a basic unit that runs independently in a real-time system, a piece of code that has no return, and can have its own running parameters, but the return type is always void.

In the real-time operating system, the entity of a task consists of the priority, task stack, and task control block 3 that the system assigns to it.

Most mobile developers, initially exposed to the development of PC system applications, mobile phones and PCs, compared to a number of differences:

1 The development of the PC application software system environment and the actual operating environment of the software is not very different; but the development of mobile software, basically in the host-pc on the development, and then download the software through the download to the target-mobile phone, development and operation is two various environments.

2 mobile phone CPU operating speed is low;

3 Mobile phone memory and hard disk capacity is small;

4 mobile phone display small;

5 when using the PC system, the basic is the use of external power supply, the power is unlimited supply (except the notebook without the charger), but the use of mobile phones, mainly using their own battery power, limited power;

6 PC system basically use the whole keyboard, but the number of keys of the phone is few, or pure touch operation, no keyboard;

7 The main function of mobile phones is to call and send and receive information, so the priority of the two tasks, that is, at any time, as far as possible to allow users to answer the phone and receive information;

8 mobile phone system has watchdog restart mechanism;

Of course there are many other differences, compared to PC development, mobile phone development can be said to be a new field.

Mobile phone software Development In addition to understanding the basic software development, programming knowledge, but also related to embedded system development, ARM development, communication protocol (GSM, GPRS, CDMA, etc.), network protocol (HTTP, TCP/IP, etc.), WAP, MMS, J2ME, serial communication and other aspects of knowledge.

Mobile phone Development Combat 1-Mobile phone introduction