Kitronik 2121 Teaching Notes Download Page 24 | Manualshive

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Kitronik 2121 Teaching Notes Download Page 24

Programmable Timer Essentials

www.kitronik.co.uk/2121

Testing the PCB

The circuit has been designed to allow easy testing of the PCB. To test the PCB you will first have to insert a chip
programmed with some software to allow it to be tested. The purpose of the test program is to test that the LED can
turn on and off, the buzzer can sound and that the switch is functioning (used to turn the LED on and off). The test
software works as shown below.

If you have problems with any of the above use the fault finding flow charts to find the cause of the fault. Please
note that these fault finding diagrams have been based around using the test software outlined above. If you are
using an alternative test program they will not be suitable.

Yes

No

Start

LED on

Wait 2 seconds

LED off

Bleep for 2 seconds

LED on

LED off

Switch

pressed?

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Summary of Contents for 2121

Page 1: ...PROGRAMMABLE TIMER KIT CREATE YOUR OWN UNQUIE TIMER WITH THIS TEACHING RESOURCES SCHEMES OF WORK DEVELOPING A SPECIFICATION COMPONENT FACTSHEETS HOW TO SOLDER GUIDE Version 2 0 ...

Page 2: ... Design Review group task Soldering in Ten Steps Resistor Values LEDs Current Limit Resistors Why use a PIC micro controller Instruction Manual Evaluation Packaging Design ESSENTIAL INFORMATION Build Instructions Build Instructions continued Checking Your Programmable Timer PCB Testing the PCB Fault Finding Fault Finding continued Designing the Enclosure Possible student programming tasks How the ...

Page 3: ...erial to aid the teacher in either case Using the booklet The first few pages of this booklet contains information to aid the teacher in planning their lessons and also covers worksheet answers The rest of the booklet is designed to be printed out as classroom handouts In most cases all of the sheets will not be needed hence there being no page numbers teachers can pick and choose as they see fit ...

Page 4: ...n for manufacture should be considered on any design project Hour 3 Read Designing the Enclosure sheet Develop a product design using the Design sheet Homework Complete design Hour 4 Split the students into groups and get them to perform a group design review using the Design Review sheet Start the Resistors sheet Homework Complete any of the remaining resistor tasks Hour 5 Using the How to solder...

Page 5: ...2 Build the kit using the Build Instructions Hour 3 Check the completed PCB and fault find if required using the Checking Your timer PCB and fault finding flow charts Hour 4 Programming task 1 The basic timer Answers Resistor questions 1st Band 2nd Band Multiplier x Value Brown Black Yellow 100 000 Ω Green Blue Brown 560 Ω Brown Grey Yellow 180 000Ω Orange White Black 39Ω Value 1st Band 2nd Band M...

Page 6: ...ill allow you to focus on specifics at the design stage and to evaluate your design Missing a key point from a specification can result in a product that does not fulfil its required task Design Develop your ideas and produce a design that meets the requirements listed in the specification At this stage it is often normal to prototype some of your ideas to see which work and which do not Build Bui...

Page 7: ... a board game The manufacturer would like you to research and select a particular use for the timer They would then like you to produce a design that is suitable for that use The design must meet all the requirements of the selected target market Description of the Timer Once the timer is started it waits for a period of time and then produces a tone using a sounder As the timer is programmable th...

Page 8: ...r Teaching Resources www kitronik co uk 2121 Investigation Research Using a number of different search methods find examples of similar products that are already on the market Use additional pages if required Name Class ...

Page 9: ... Specification Using your research into the target market for the product identify the key requirements for the product and explain why each of these is important Name Class Requirement Reason Example The enclosure should have some holes Example So that the sound can be heard ...

Page 10: ...Programmable Timer Teaching Resources www kitronik co uk 2121 Design Develop your ideas to produce a design that meets the requirements listed in the specification Name Class ...

Page 11: ... see if you can spot any additional aspects of each design that may cause problems with the final product This will allow you to ensure that you have a good design and catch any faults early in the design process Note each point that is made and the reason behind it Decide if you are going to accept or reject the comment made Use these points to make improvements to your initial design Comment Rea...

Page 12: ...ring iron has warmed up and if necessary use the damp sponge to clean the tip 5 Place the soldering iron on the pad 6 Using your free hand feed the end of the solder onto the pad top picture 7 Remove the solder then the soldering iron 8 Leave the joint to cool for a few seconds 9 Using a pair of cutters trim the excess component lead middle picture 10 If you make a mistake heat up the joint with t...

Page 13: ... 0 0 1 Brown 1 1 10 1 Red 2 2 100 2 Orange 3 3 1000 Yellow 4 4 10 000 Green 5 5 100 000 Blue 6 6 1 000 000 Violet 7 7 Grey 8 8 White 9 9 Example Band 1 Red Band 2 Violet Band 3 Orange Band 4 Gold The value of this resistor would be 2 Red 7 Violet x 1 000 Orange 27 x 1 000 27 000 with a 5 tolerance gold 27KΩ Resistor identification task Calculate the resistor values given by the bands shown below T...

Page 14: ... measured will be within 5 of its stated value Tolerances are important if the accuracy of a resistors value is critical to a design s performance Preferred values There are a number of different ranges of values for resistors Two of the most popular are the E12 and E24 They take into account the manufacturing tolerance and are chosen such that there is a minimum overlap between the upper possible...

Page 15: ...urrent limit resistor the LED would be very bright for a short amount of time before being permanently destroyed To work out the best resistor value we need to use Ohms Law This connects the voltage across a device and the current flowing through it to its resistance Ohms Law tells us that the flow of current I in a circuit is given by the voltage V across the circuit divided by the resistance R o...

Page 16: ...lt to break than a bulb Small LEDs can be made very small This allows them to be used in many applications which would not be possible with a bulb Fast turn on LEDs can light up faster than normal light bulbs making them ideal for use in car break lights Disadvantages of using LEDs Some of the disadvantages of using an LED over a traditional bulb are Cost LEDs currently cost more for the same ligh...

Page 17: ...ages of using PIC micro controllers Complex functionality can be produced a very low cost Circuit size as described above It is very easy to make minor alterations to the function of the product o These include changing the length of the delays and the duration of sounds o The ability to change the tone of the buzzer and even play musical tunes if so desired Flexibility The circuit could easily be...

Page 18: ...truction Manual Your programmable timer is going to be supplied with some instructions Identify four points that must be included in the instructions and give a reason why Point to include Reason Point to include Reason Point to include Reason Point to include Reason ...

Page 19: ...ecification Show your product to another person in real life this person should be the kind of person at which the product is aimed Get them to identify aspects of the design which parts they like and aspects that they feel could be improved Good aspects of the design Areas that could be improved Improvements Every product on the market is constantly subject to redesign and improvement What aspect...

Page 20: ... your product was to be sold in a high street electrical retailer what requirements would the packaging have List these giving the reason for the requirement Requirement Reason Develop a packaging design for your product that meets these requirements Use additional pages if required ...

Page 21: ...PROGRAMMABLE TIMER KIT ESSENTIAL INFORMATION BUILD INSTRUCTIONS CHECKING YOUR PCB FAULT FINDING MECHANICAL DETAILS HOW THE KIT WORKS Version 2 0 CREATE YOUR OWN UNQUIE TIMER WITH THIS ...

Page 22: ...to the board where it is labeled PROG Solder the Light Emitting Diode LED in to LED1 The timer won t work if it doesn t go in the right way around If you look carefully one side of the LED has a flat edge which must line up with the flat edge on the lines on the PCB The battery clip should be soldered into the POWER terminal First start by feeding the wire through the strain relief hole feed from ...

Page 23: ...insert the batteries Check the bottom of the board to ensure that All holes except the 4 large 3 mm holes INPUT2 are filled with the lead of a component All these leads are soldered Pins next to each other are not soldered together Check the top of the board to ensure that The notch on the IC and the IC holder are in the same orientation as the markings on the printed circuit board R2 has Brown Bl...

Page 24: ...d off the buzzer can sound and that the switch is functioning used to turn the LED on and off The test software works as shown below If you have problems with any of the above use the fault finding flow charts to find the cause of the fault Please note that these fault finding diagrams have been based around using the test software outlined above If you are using an alternative test program they w...

Page 25: ...or dry joints IC1 pin 1 2 for a short The power connections for dry joints The power connections are the right way around Go to page 2 Start Does the LED light Power the board up whilst watching the LED No Yes but only very dimly Yes Check R3 for dry joints IC1 pin 6 for a dry joint or short to an adjacent pin The LED for a short dry joints and that it is in the right way around R3 is in the wrong...

Page 26: ...pin 5 for a dry joint The sounder connections for a dry joint Yes but quietly Yes Fault finding flowchart Page 2 Continued from page 1 Stop Does the LED light when the switch is pressed Check IC1 pin 4 for a dry joint Input 1 the switch connections for dry joints The switch is connected to Input 1 not input 2 No Yes Yes but it flickers stays on once the switch is released There is a dry joint on R...

Page 27: ...nted right Access to the batteries to allow them to be changed below right Technical drawings of these items are illustrated on this page which should help you design your enclosure All dimensions are in mm Mounting the PCB to the enclosure The drawing to the left shows how a hex spacer can be used with two bolts to fix the PCB to the enclosure Your PCB has four mounting holes designed to take M3 ...

Page 28: ... one second out of time buzzer sounds it will give a short bleeps to warn the time is almost up Task 3 User configurable delay A special mode will be added to set how long the delay is so the timer can be reprogrammed during normal use without a PC Task 4 Musical The final task will be to replace the time out tone with a tune Student guides available on line To guide students through the programmi...

Page 29: ...on the input to the PIC to a low voltage When the switch is press closed the voltage on the PIC pin is pulled up to a high voltage You will be able to read this change of state in your software Input 2 has been left as a spare input should you wish to add another input device The pull down resistor R5 which is the same as that used on Input 1 is already included The purpose of resistor R3 is to li...

Page 30: ...t educational schemes of work and so on and also includes the essentials Download from www kitronik co uk 2121 Every effort has been made to ensure that these notes are correct however Kitronik accept no responsibility for issues arising from errors omissions in the notes Kitronik Ltd Any unauthorised copying duplication of this booklet or part thereof for purposes except for use with Kitronik pro...

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