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EE2079 DIP


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Cash register that can tally the amount of cash in it

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EE2079 DIP

  1. 1. 1. IntroductionAccounting for money is an important component in business management. In the retailindustry, this is especially the case when dealing with large amount of inventories. Bigcorporations like Wal-Mart and Fairprice use the point of sale system (POS) for theirtransactions. Taking this concept, the project aims to develop a small POS system that acts asan electronic cash register and money counter that accounts for the sales of the day bycalculating the amount of money (coins and notes) inside the cash register using sensors.This system will be helpful for small and medium enterprises as it will be cheaper and lesscomplicated than the actual POS system. Our idea is that we can attach a small sensors on thedifferent compartments of the cash register to record the amount of coins or notes insertedaccording to its value assigned on the compartment. Therefore the sum of the money can betallied together and matched with the sales.2. Designing processWe want to design the cash register as physically close to the cash register that is on themarket today. We also consider the money counter and coin sorter design to incorporate intoour design. After brainstorming and discussions, we have encountered a few problems.1. The type of sensors suitable. Coins and notes require different techniques of sensing2. Algorithm and codes for calculation. The software component of the system.3. Integration of the program and the cash register to a computer, finding a suitableinterface chipFor this project, we make a simulation of the process using a box with buttons torepresent the different compartments of the cash register. There are 7 compartments duringthe simulation. 5 are buttons and 3 are toggle switches. 1 button is used for summing function.A sensor is connected to the toggle switches to represent that each compartment areconnected by one sensor. The sensor uses will sense the coins. The layout of the simulation isrepresented on appendix B3. Main equipments1x PhidgetInterfaceKit 8/8/8 $150Using this interface kit, we can directly convert the sensing which is analog countingconvert to digital signal that can be read by the computer. Also its major advantage is itcan be connected directly to the computer using a USB port.3x Toggle switches $1-2 per piece5x Switches $1-2 per pieceFor the simulation of sensing the coins and notes
  2. 2. 1x Proximity sensor around $20For sensing coins.4. HardwareAs mention early, the box that we created act as a simulation for the actual product. Thereason we choose the phiget interface kit is that converting analog to digital signal require acomplex electronics configuration to implement. Thus by using the interface kit, we canmake use of this available technology to allow direct connection. This way, it saves bothmoney and increase efficiency of the whole system without creating a complex structure.The placement of the sensors is determined after the considerations of the coin sortermachine structure. As the coin sorter differentiate coins through mechanical spinning of adisk and sorting by the size of the coin. A hole is made to allow the different size of coin toenter into its individual compartment.Therefore by placing sensors at the side of the opening of different compartment in thecash register, we can get the amount of coins to be calculated individually.Placement of A sensor on a coin compartmentThe sensor we use is proximity sensor. It works by emitting an electromagnetic field thatdetects any object that is within its field. The reason we use proximity sensor is because it issensitive and it does not require any physical contact for the sensor to detect the coin. It is quitecheap and user friendly without any physics background. User just requires knowing the range ofthe electromagnetic field. Connection of the sensor is shown below.
  3. 3. As it can be seen, there is a need for a ‘common’ ground, to prevent electrical anomaliesand safety.Improvements to considerFor the notes counting, we require different type of sensor to calculate as notes does notcontain metallic object. We can use maybe a small laser sensor to detect the notes. For coins,we can make the sensor as small as possible to fit into the cash register maybe into a nanosize sensor. This way we reduce the size and cost of the cash register. The sensor only candetect one coin at a time. We can form need more sensors to include more coins to bedetected at one time5. SoftwareThe programming software we use to write the code is Visual C++ which is being taughtin Year 1 computing course. It will provide the ‘skeleton’ of the program and it will beconverted to Visual Basic for a better graphic representation of the program. The code isshown in appendix A.Basically it is a simple code that collects the digital signal from the different input ofinterface kit which represents the different compartments of the cash register. After the totalfunction is activated by the total button, the total of each input will be multiply together withthe values that are assigned and then the values will be summed together giving the totalsales of the day.The most important part of code is that is it simple. The program returns the sum hence itcan be represented with a notation of O(n1+…+nx) as it is the summing of x amount offunctions.Improvements to considerThe current code only can count by adding the coins. The cashier is required to take outof all the coins inside the compartment and pour them back again after activating the
  4. 4. program. We can rewrite the code to include subtraction to allow the cashier to take in andout the coins due to the transaction with customer without hassle.Also we can implement more functions like undo, recount6. Integration of software and hardwareThis process took up the most of the time in this project. We require following thecode provided by phidget allowing the program and the sensor to run together and thecomputer need receive the input of the sensor for calculations. This product requirephidget driver to run interface kit. Also the circuit design of the product require properconfiguration.The interface kit has to be activated by the initialization code that is provided by thecompany. The code requires some modifications to apply to our project.The system works using in active high. It means the signal is initially set to 0. Afterthe sensor detects a coin, it will transmit a signal and activate the value to 1 to thedifferent index on the chip, which in turn will be activated by the sensor signal. Afterboth of them are activated to 1, the program will start the count loop.7. MarketabilityThis product will be suited for small and medium enterprise that does not requirethe actual POS system as they do not have a large amount of inventories. This productallow the boss to monitor the daily sales and to prevent workers from stealing as all thesales will be saved in the computer and tallied at the end of the day.8. ConclusionIn this project, we have learnt to use an interface kit to integrate the program andthe sensors together to form and counting cash register. We learn and select the suitablesensor for coin detection. Using the proximity sensor we can sense the amount of coinsinside the compartment in a fast and efficient way.We write an addition code from scratch using Visual C++ and the knowledgefrom the computing course. Additionally, we combine this knowledge with the specificinitialization code provide by phidget company to activate the interface kit to detect thesignals from the sensor. In the end created a system of the cash register.9. ReferenceInductive proximity sensor
  5. 5. Programming code; AAppendix B