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1、 .wd.Design of electronic storage cabinet based on RTOS SmallDepartment of electronics and communication engineering, PSG college, Coimbatore IndiaAbstract：This paper introduces the design principle of the electronic storage control system based on RTOS Small, and introduces the system used in this
2、system to make the controller, which can manage the N storage cabinet at the same time. The door lock is controlled by the electromagnetic valve, when customers need to save the package, can go to the lockers before press the open button, the microcontroller receives a pulse signal, and the system I
3、/O port to send corresponding signals to control the electromagnetic valve lock door will be an empty box is opened, the customer can save the package and the door shut. When the customer needs to take the package, will as long as the bar code placed in front of the bar code reader, barcode reader b
4、ar code information collected by the output voltage signal corresponding to the microcontroller, the password system is relatively consistent, send out signals to the solenoid valve is open, the customer can remove the package.Key words：Small RTOS；electronic storage cabinet; save package1、Introducti
5、onRTOS RAM Small demand for small, very suitable for such a relatively small resources of the system. RTOS has a multi tasking, strong real-time, and can be reduced to the kernel, making the design of real-time applications, expansion and maintenance easier. The introduction of the idea of RTOS, ins
6、tead of the traditional software design method, so that it is no longer a single thread structure, through the application is divided into several independent tasks, RTOS makes the design process of application system is simplified. In this paper, the software design of electronic storage cabinet ba
7、sed on single chip microcomputer is combined, the design idea of RTOS Small and the application of message queue communication mechanism are briefly analyzed.1.1 basic principles of RTOS51 SmallRTOS51 Small is a very small kernel, fully integrated in the C51 KEIL compiler, only take less memory spac
8、e, you can run in the 51 single chip microcomputer system without external data memory. The kernel is responsible for initializing and open, other tasks scheduling system, according to the priority of tasks, a reasonable distribution of CPU in different time between tasks, the kernel can generally p
9、rovide task scheduling and interrupt service function. A program and a task, the task of each separate, independent implementation of the part called thread. All event driven and time driven are reflected in the settings of the corresponding task identification and thread identification. When the ha
10、rdware environment, on the basis of the identification, by arranging the system interrupt and task scheduling algorithm adjust the response, by using the method of setting up environmental variables, which can interrupt exit after return to any more than one set of entrance in one to perform, and ef
11、fectively solves the key problem of flexible switching of foreground and background tasks thread. RTOS Small 51 user tasks with a running state, ready state, wait and suspend, interrupt service program. At any moment, the state of the task is one of these four states. In order to save memory, create
12、 and delete mission OS dynamic, with the function OSSTART () to start a multi tasking environment, OS took all the tasks set up, and set them as the ready state, the highest priority task to run. Only when all the priority is higher than its task to wait. Ready to enter a state of operation. The sch
13、eduler will be the top priority of the task ready list as the next task to be performed.Task call os_wait function, pending the current task, waiting for one or several intervals (K_IVL), time out (K_TMO), signal (K_SIG) events. If waiting for event has occurred, continue to implement the current ta
14、sk; if waiting for events did not occur, the corresponding waiting sign, suspend the task to task switching program segment switch to the next task.Small RTOS51 (init) by performing a function to register initialization, call the function OSSTart () to initialize each task stack and perform the firs
15、t task, and the choice of the first task for the reason that the task priority level. In the selection process to complete the task of scheduling.1.2 communication between tasksCommunication between tasks using the message queue, after 3 steps: to create a message queue OSQCreate (), to the message
16、queue message OSQPost (), take message OSQPend (). Call the OSQPost () function to send the message, if you already have a task waiting for the message, immediately turn to wait for the news task, if the message queue is full, is unable to deliver the message, return an error. If the message queue is not full, but there is no other task waiting for the message, then. It is worth noting that, when the queue is full, the
