Control System Of An Electronic Receipt Cabinet

The core component of Automatically-Returned Bill Machine is the Bill Machine's management and control system, whose main characteristic is the computer and modern control technology. A system was developed in order to meet the needs of financial services. The structure, working principle and control method of the system were systematically introduced in this thesis.The management system depends on the high performance system host executing visualized and object oriented management program to complete the functions such as send the In/Out bill instruction to the control system, user authentication, customer information query, customer account management, intelligent filter, customer information security management, print list, video display, Bill Box dynamic allocation , etc.The control system real-time control and monitor the returned bill machine according to the instructions sent by the management system to implement the Bill Box automatic access and state feedback, and monitor the main hardware such as system power.The hardware include returned bill control circuit, power and communicating control circuit and returned Bill Box control circuit. returned Bill Box control circuit is controlled by a single chip computer to complete the following functions:(1) Serial Communication with the system host,(2) Select the target Bill Machine and according to the system host instruction;(3) Open the target Bill Box automatically;(4) Detect the open/closed state of the target Bill Box;(5) Detect the bill state in the target Bill Box;(6) Feedback the detect results to the system host.The main functions of power and communicating control circuit are as follows:(1) System power centralized control;(2) Communication signal level's translation and drive;(3) Audio signal's power amplification. The functions of Bill Box control circuit are as follows:(1) Opens and closes the returned bill box electromagnet,(2) Send the open/close state detecting signals of the Bill Box to single chip computer;(3) Send the bill state detecting signals in the Bill Box to single chip computer.The system software is composed of the communication protocol and the control program of the system host and the single chip computer. The control program of single chip computer include main program and interrupt service program. The main program implements system initialization. The interrupt service program implements all of the control and detection.Time delay control technology is used in order to receive accurate detecting signals.The Bill Box is closed manually, therefore the control program doesn't know when it closes. Thus the system sets a limit for the waiting time of box closure. This time limit can be adjusted anytime by the system host via control instructions. If a negative pulse closing signal is detected within the box closure waiting time limit, then the status message"the target Bill Box is already closed"is immediately sent to the system host; If it passes the waiting time limit and still has not detected the negative pulse signal, then the message"the target Bill Box is not closed yet"is sent to the system host.To avoid the chaos and false information on the open/close status and deposit receipt examinations that are caused by the vibration of the dry reed relay sensors, and to acquire accurate information on the target Bill Box's closure, we adopted a delay subroutine to avoid the closure examination of the Bill Box immediately after the openning examination. We discovered in the debugging process that when the Bill Box is opened and closed, the output of comparator sends multiple negative pulse signals. This creates false information later on the closure and deposit receipt examination. The second pulse can easily be mistaken as door closing or receipt coming signal. This is because the Bill Box's opening and closing as well as the deposit receipt examination methods are essentially the same, they are only differentiated by the gap in timing. The small magnet's field change when passing the dry reed relay causes the dry reed relay sensors to vibrate, which is the main reason for the multiple negative pulses output from the comparator. Although the reason has been clear, it is extremely difficult to eliminate the problem. How do we address the issue then? We propose a delay technique.To avoid the system lockdown caused by external disruptions, we specifically designed the WDT-Reset circuit for the single chip computer control circuit.We set this WDT triggering programs at multiple locations in the main program and the interrupt servicing program. Under normal circumstances, the control program won't be reset because the WDT's trigger interval is less than 1.6 seconds. However, if the program enters an endless loop for some reason, the single chip computer will reset and the control program will be resurrected to run, because it fails to execute the WDT trigger program within 1.6 seconds. This automatic procedure is a very important feature to guarantee the system's security and reliability.It is safe to say that people are active in research in the related fields of the above technologies and yield encouraging result. We will integrate these technologies and apply them to the development processes.