Printer Carriage Motion Control LaboratoryPrinter Carriage Motion ControlLearning ObjectivesBy the end of this laboratory experiment, the experimenter should be able to:- Use a quad push-pull driver chip for bi-directional dc motor control.- Use reflective photo-switches, opto-interrupter switches, and micro-switches for motion control.- Explain how and why limit switches are used to prevent over-travel.ComponentsQty. Item1 ATmega16 microcontroller, STK500 board, and serial port cable.1 Solderless breadboard1 Printer carriage assembly1 Optical-interrupter switch (Fairchild H21LTB)1 Photo-reflective opto sensor (Fairchild QRB1134)2 Roller lever momentary switch (Omron SS-5GL2)1 SN754410 (Quad Half-H driver) or L293D (Quad Push-Pull driver with diodes)1 74LS04 hex inverterOverviewThe purpose of this lab is to help you learn how construct a system with multiple sensors and an actuator and interface these with the ATmega16 microcontroller. Figure 1 shows how all the components come together to complete the printer system. The procedure below will guide you inbuilding and testing pieces of the system and then integrating them into a complete system.Figure 1. Printer carriage system. The printer carriage system contains: two sensors: a photo-reflective opto sensor and photo-interrupter switch; a power interface (the SN754410 and 1/6 of the 74LS04); the carriage motor, and two SPST switches to provide fail-safe end-of-travel limits. The connections between the modules and the STK500 -San José State University Department of Mechanical and Aerospace Engineering rev 1.1.2 19OCT2010 ATmega16 & STK500IN 1IN 2EN 1SN75441074LS04+5V10 kOUT 1OUT 2motorreflective optooptointerrupterLimitSW 1LimitSW 2tact switch+5VOPTO POWEROPTO GND+7V+5VA switch on the STK500. Page 1 of 7Printer Carriage Motion Control Laboratoryare made through 5-way binding posts on the printer carriage assembly. The opto sensors and the SN754410 need +5 V to operate, and +7 V will be applied to the VS pin of the SN754410 to power the motor.IntroductionSwitches are common devices that permit or interrupt the flow of current In addition to simplycontrolling electrical power to a device (such as a motor or light), they can be used in motioncontrol to detect whether or not a movable element has reached a predetermined position.Mechanical switches come in a variety of designs. They are categorized by the number of poles and throws they have. The number of poles represents the number of separate circuits that can be completed by the same action of the actuating lever or button. The number of throws represents the number of individual contacts for each pole. The most common types are shown in Figure 2 below.Figure 2. Examples of different switch configurations. The number of poles represents the number of separate circuits that can be completed by the same action of the movable contact(s) inside the switch. The number of throws represents the number of individual contacts for each pole. Micro-switches typically refer to mechanical switches of small size that have a spring-loaded, momentary contact, operated by a push-button directly or via a pivoted cantilever. Micro-switchesfind use in many consumer products such as notebook computers, appliances (to detect if a cover is closed), etc. Switches are comprised of moving or sliding mechanical elements are designed to operate for thousands to hundreds of thousands of on-off cycles. (What type of switch are the buttons on the STK500?)Opto-switches (e.g. opto-interrupters, etc.) are non-mechanical switches that use a light-emitting diode (LED) and a phototransistor. Light from the LED shines toward the base of a photransistor across a gap in the housing of the switch. The output of the photransistor will indicate whether or not something is blocking the light from the LED. Opto-interrupters are often used in mechatronicdevices to indicate that a movable element has reached its desired position or end-of-travel. Examples include printers, copiers, and manufacturing automation. Opto-interrupters are attractive to use, because they are solid-state, reliable, relatively inexpensive, and are straightforward to interface with logic circuits. Since they operate without physical contact, they have the advantages of longer lifetime, higher reliability, and faster actuation time compared to mechanical switches. You are going to use two types of opto-switches, a reflective (Fairchild QRB1134) and an interrupter-type (Fairchild H21LTB) on a printer mechanism and use them in driving a printer carriage between preset limits. You will also use two SPST microswitches to provide a fail-safe limit on the end-of-travel of the carriage in case one of the opto-switches fails. Assembling the SystemLike we have done in past expermiments, we will again construct the system in a modular way by building and testing pieces of the system as we go. This is a good general approach in any kind of electronic work, system design, or even computer programming. Avoid the temptation to wire everything up first and hope that it will all work the first time. Such an approach is doomed to fail,-San José State University Department of Mechanical and Aerospace Engineering rev 1.1.2 19OCT2010 Single-pole/single-throw (SPST) Single-pole/double-throw (SPDT) Double-pole/double-throw (DPDT) Double-pole/single-throw (DPST) Page 2 of 7Printer Carriage Motion Control Laboratoryand you’ll end up spending more time trying to figure out what is not working than if you just build and test subsystems as you go along.First you will work with the sensors, and make sure that they are working properly; then you’ll connect the sensors to the ATmega16; then you’ll work with the SN754410 chip; then you will pull everything together to complete the printer system.Get a printer carriage assembly from your lab instructor. The next three sections will guide you through some tests to make sure that all the sensors on the assembly are working properly.Reflective Opto-switchFirst, before connecting anything, check that the reflective opto-switch, which is mounted on a bracket and attached to the side of the printer closest to the motor, is operating properly using theprocedure below.1. Set the +6V output terminal on the HP E3630A Triple Output Power Supply to output +5V. Using banana-to-banana test leads, connect the +5V output and the Common output from thepower supply to the respective OPTO POWER and the OPTO GND jacks on the printer carriage