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| − | | + | For an excellent introduction guide, we recommend [https://www.flowcode.co.uk/education/ Introduction to microcontroller programming] |
| − | The task is to produce a Flowcode flowchart that lights a lamp for ten seconds when a switch is pressed.<br />
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| − | Although it may not be realistic to use a microcontroller in such a straight-forward application, it illustrates the technique of producing a Flowcode program.<br />
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| − | The program itself may form part of a bigger program.
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| − | __TOC__
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| − | | |
| − | ==Formulate the sequence==
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| − | The flowchart sequence will be:
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| − | : Check if the switch is pressed.
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| − | :: If it isn't, go back to the beginning.
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| − | :: If it is:
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| − | ::: switch on the lamp;
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| − | ::: wait for 10 seconds;
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| − | ::: switch off the lamp;
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| − | ::: go back to the beginning.
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| − | It takes such a short time for the microcontroller to carry this out, that we don't need to worry whether the switch latches on or not.
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| − | ==Set up the flowchart==
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| − | [[File:Gen_Startup_Selection.png||250px|right]]
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| − | * [[Opening Flowcode|Open Flowcode]].
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| − | * On the Startup screen, click on 'New embedded project'.
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| − | [[File:Gen_Project_Options_Target_16F1937.png|right|250px]]
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| − | : The [[Project Options]] dialogue box opens.
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| − | : (Click on the link for a full explanation of all the options available.)
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| − | | |
| − | * Accept the default settings by clicking on 'OK'.
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| − | : An empty flowchart window opens, which may contain other items such as a [[System Panel]], [[Dashboard Panel]], [[Properties Panel]] etc.
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| − | : These can be revealed or hidden using the [[View]] menu.
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| − | * Set up the flowchart window so that you can see the System Panel and the Properties Panel.
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| − | : The flowchart window should resemble the one shown below (depending on the configuration.)
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| − | [[File:gen_exerciseFirstFlowchart_startscreen_01.png|500px|center]]
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| − | | |
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| − | : The System Panel and Properties Panel can be moved by 'clicking and dragging the title bar at the top of each panel.
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| − | ==Set up the input==
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| − | : More information about the icons used in this flowchart can be found in [[Icon Properties]].
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| − | * Drag and drop a 'Loop' icon between the BEGIN and END icons.
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| − | : The 'Loop' icon makes the microcontroller repeatedly run through the program, (though the icon can be configured to limit the number of times this happens.)
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| − | [[File:Gen exerciseFirstFlowchart newvar 01.png|250px|right]]
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| − | | |
| − | * Inside the loop, drag and drop an 'Input' icon from the [[Tools and Views#1) Icons Toolbar|Icons toolbar]].
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| − | :* Double click on the icon.
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| − | :: This opens the 'Properties: Input' dialogue box, allowing you to configure the way the program treats information from the switch.
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| − | :: This information will be contained in a variable called 'switch'.
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| − | ::* Click on the down arrow at the right-hand end of the 'Variable:' box to open the variables dialogue box.
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| − | ::* Hover to the left of the 'Variables' label and click on the down arrow that appears.
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| − | ::* Click on the 'Add new' option to open the 'Create a New Variable' dialogue box.
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| − | ::* [[Creating Variables|Create a new variable]] named "switch" with initial value "0" and description "Copies the state of the switch"
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| − | | |
| − | ::* Leave the 'Variable type:' as 'Byte'.
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| − | ::: (For more information about variables, see [[Creating Variables]] and [[Variable Types]].
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| − | ::: (The resulting dialogue box is shown opposite.)
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| − | [[File:gen_exerciseFirstFlowchart_inputprops_01.png|250px|right]]
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| − | | |
| − | :* Finish configuring the input properties as follows:
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| − | ::* Change the 'Display name:' to "Read the switch".
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| − | ::* In the 'Variable:' box, type the name of the variable you created "switch".
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| − | ::* Leave the 'Port:' as PORT A.
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| − | ::* Select to 'Input from:' 'Single Bit' and choose bit 0.
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| − | ::: (The resulting dialogue box is shown opposite.)
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| − | : Set up like this, the program monitors the state of the switch, which will be connected to bit 0 of Port A of the microcontroller.
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| − | : When the program looks at the input switch if it is pressed, the variable 'switch' contains logic 1. If unpressed, it contains logic 0.
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| − | ==Check the switch==
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| − | [[File:gen_exerciseFirstFlowchart_deciconprop_01.png|250px|right]]
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| − | * Drag and drop a 'Decision' icon after the 'Input' icon.
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| − | :* Double click on it to open the configuration dialogue box, and then:
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| − | ::* Rename it "Switch pressed?".
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| − | ::* In the 'If:' box, type "switch=1".
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| − | ::* Leave the 'Swap Yes and No' box unchecked.
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| − | ::* Click on 'OK'.
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| − | | |
| − | : This icon makes the program perform what is known as a conditional branch.
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| − | : The subsequent course of the program depends on the outcome of the condition specified in the 'Decision' icon.
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| − | : In this case, it depends on whether or not the variable 'switch' = 1.
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| − | : If it is, the program follows the 'Yes' route. If not, it follows the 'No' route.
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| − | ==Control the lamp==
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| − | : The 'No' branchis easy to set up. All we want is that the program returns to the beginning (taken care of by the 'Loop' icon.)
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| − | : No further configuration is needed.
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| − | [[File:gen_ exerciseFirstFlowchart_ outputprops_ 01.png|250px|right]]
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| − | : Next we concentrate on the 'Yes' branch.
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| − | * Drag and drop an 'Output' icon in the 'Yes' branch.
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| − | :* Double click on it to open the configuration dialogue box, and then:
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| − | ::* Change the 'Display name:' to "Switch on".
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| − | ::* In the 'Variable or value:' box, type value "1".
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| − | ::* Change the 'Port:' to PORT B.
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| − | ::* Select to 'Output to: 'Single Bit' and choose bit 0.
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| − | ::* Click on 'OK'.
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| − | ::: (The resulting dialogue box is shown opposite.)
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| − | : The effect of this icon is to send a logic 1 signal (high voltage) to the lamp, connected to Port B, bit 0 of the microcontroller.
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| − | : This turns on the lamp.
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| − | : Now, we tackle the requirement that it stays on for ten seconds and then goes off.
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| − | [[File:gen_exerciseFirstFlowchart_delayiconprop_01.png|250px|right]]
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| − | * Drag and drop a 'Delay' icon after the 'Output' icon.
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| − | :* Double click on it to open the configuration dialogue box, and then:
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| − | ::* Change the 'Display name:' to "For 10 seconds".
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| − | ::* Leave the 'Delay value:' as '1'.
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| − | ::* Change the unit to 'seconds.
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| − | ::* Click on 'OK'.
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| − | ::: (Again, the resulting dialogue box is shown opposite.)
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| − | [[File:gen_exerciseFirstFlowchart_outputprop2_01.png|250px|right]]
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| − | : Finally, we need to turn off the lamp, after the ten second delay.
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| − | : To do this:
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| − | * Drag and drop a second 'Output' icon after the 'Delay' icon.
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| − | * Double click on it to allow you to configure it.
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| − | : Rename it "Switch off", and configure it to deliver value "0" to single bit 0 of Port B.
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| − | : The resulting dialogue box is shown opposite.
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| − | You should now save the flowchart as "Lamp1.fcf", and [[Closing Flowcode|close Flowcode]].
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| − | ==What next==
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| − | The next step is to add the switch and lamp to the flowchart. This is covered in the exercise [[Adding Devices to a Flowchart]].
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