Controlling the Robotic Arm using the BBC micro:bit

Transcription

1 Controlling the Robotic Arm using the BBC micro:bit You need to plug the BBC micro:bit into a computer using a USB cable or sync to it using Bluetooth after downloading the correct app from your app store. This guide assumes you have already done that!!! If you need help, get in contact support@cbiseducation.com If you want to use a fifth motor, you will have to connect it to pin 11 and pin 16, when connecting to pin 11, you cannot use Button B The guide below assumes you are using four motors and not five Once you have wired up the robotic arm, head over to the BBC micro:bit website: and click on the Let s Code button Find the JavaScript Blocks Editor (PXT) section and click on the Let s Code button

2 Click on projects new project Next you will need to rename the project so it is easier to locate later on in the activity Get rid of all the blocks on the page, this can be done by dragging them to the left, over the tabs

3 Click on the Basic tab, select the on start block and drag it onto the page Click on the Variables tab, select the set item to block and drag it in-between the on start block

4 Click on item and rename it to MotorNumber Again, click on the Variables tab, select the set item to block and drag it below the set MotorNumber block Rename the item variable to CurrentMotor Now we need to stop power going through to the pins when the robotic arm turns on. To do this, click on the Advanced tab, then the Pins tab, select the digital write pin block and place it underneath the set CurrentMotor block.

5 Now we need to add the other seven pins, to do this duplicate the digital write pin seven times and place them underneath each other Next we need to replace the P0 in each of the statements with the corresponding pins from the wiring diagram previously

6 Now we need to show the motor number, click on the Basic tab, select the show number block and place it underneath the digital write pin block

7 Now, click on the Variables tab, select the MotorNumber block and drag it over the 0 from the show number block Now we need to create a bit of code to select a motor number. Click on the Input tab, select the on button A pressed block and drag it onto a blank section of the page Now, we need to create an if statement so that each time button A is pressed it will count up to 6

8 Click on the Logic tab, select the if statement and drag it in-between the on button A pressed block Click on the Logic tab, select the 0=0 block and place it over the true block on the if statement

9 Next click on the Variables tab, select the MotorNumber block and drag it over the first 0 in the 0=0 block. Then change the second 0 to 5 this tells the micro:bit that when the variable MotorNumber reaches 5 it will run the statements below, in the then section Next, click on the Variables tab, select the set item to block and drag it into he then section of the if statement Change the item to MotorNumber, then duplicate and place in the else section

10 Now we need to set the counter. To do this, click on the Math tab, select the 0+0 block and drag it over the 0 on the second set MotorNumber to block Click on the Variables tab, select the MotorNumber block and drag it over the first 0 on the 0+0 block, then change the second 0 to 1 Click on the Basic tab, select the show number block and drag it underneath the if statement

11 Click on the Variables tab, select the MotorNumber block, drag and replace the 0 from the show number block Now we need to set button B so that when it is pressed it locks the number so you can move the motor chosen Click on the input tab, select the on button A pressed block and drag it onto the page

12 You will see that the block has now been greyed out, click on the A and change it to B Next, click on the Variables tab, select the set item to block an drag it in-between the on button B pressed block Click on item and rename to CurrentMotor

13 Next, click on the Variables tab, select the MotorNumber block, drag and replace the 0 from the set CurrentMotor to block We now have created code for button A and button B, next we need to create the code that goes on behind the scenes Click on the on the Basic tab, select the forever block and drag it onto the page Next, click on the Logic tab, select the if statement and drag it in-between the forever block

14 Click on the blue cog and drag an else if underneath the if statement to create another section Click on the Logic tab, select the 0 < 0 block and drag it over the true block Now we need to tell the micro:bit that if you tilt it left, the motor will turn left etc.

15 Click on the Input tab, select the acceleration block and drag it over the first 0 Now, change the 0 to -300 when you are using numbers on the X axis, minus - numbers are for when you want the micro:bit to tilt left and positive numbers are for when the micro:bit tilts right Now we need to tell the micro:bit to show a directional arrow but also control the motors. Click on the Basic tab, then More and select the show arrow block. 3. Drag the show arrow block into the then section of the if statement

16 Click on the north block and change it to west this changes the arrow so when you tilt the micro:bit left, the arrow will point left or west on a compass Click on the Logic tab, select the if statement and drag it underneath the show arrow block Click on the blue cog icon located on the if statement

17 Now drag the else if block underneath the if block on the right. Repeat two more times to have a total of 3 else if blocks Now we need to tell the micro:bit to move the robotic arm motors, to do this we define a variable for each motor. Click on the Logic tab, select the 0=0 block, drag and drop it to the right of the if statement, replacing the true block

18 Click on the Variables tab, select the CurrentMotor block and drag it over the first 0 on the 0=0 statement Change the second 0 to 1 this statement tells the micro:bit, that if the motor selected with button B is number 1 then run the code we are going to put in the then section

19 Next, click on the Advanced tab, then the Pins tab. Select the digital write pin block and drag it into the first then section of the if statement Duplicate the digital write block and place it underneath

20 Now we need to change the pin number and the value of the pins Change the 0 in the first digital write pin block to 1, then change the Pin on the second digital write block to P1 this will move the base motor left Now we need to create the second motor function Duplicate the CurrentMotor = 1 block, drag and snap into place on the right of the first else if section Change the 1 to 2

21 Next, click on the Advanced tab, then the Pins tab. Select the digital write pin block and drag it into the second then section Duplicate the digital write block and place it underneath Change the pin from P0 to P8 and 0 to 1 on the first digital write statement.

22 Next, change the pin from P0 to P12 on the second digital write statement this will create a section of code to control the second motor Duplicate the CurrentMotor = 2 block, drag and snap into place on the right of the second else if section Replace the 2 with 3

23 Next, click on the Advanced tab, then the Pins tab. Select the digital write pin block and drag it into the third then section Duplicate the digital write block and place it underneath Change the pin from P0 to P2 and 0 to 1 on the first digital write block, then change the pin to P13 on the second digital write block this creates the block of code to control the third motor

24 Duplicate the CurrentMotor = 3 block, drag and snap into place on the right of the third else if section Replace the 3 with 4 Next, click on the Advanced tab, then the Pins tab. Select the digital write pin block and drag it into the fourth then section

25 Duplicate the digital write block and place it underneath Change the pin from P0 to P14 and 0 to 1 on the first digital write block, then change the pin to P15 on the second digital write block this creates the block of code to control the fourth motor Now we need to create a block of code so when the micro:bit tilts right the motors turn anticlockwise

26 Click on the Logic tab, select the 0 < 0 block and drag it to the right of the else if on the first if statement Click on the Input tab, select the acceleration block and drag it over the first 0 on the 0 < 0 statement Next, change the < symbol to >, then 0 to 300 Duplicate the whole if statement located in the first then section and place it below the acceleration > 300 block

27 Next, we need to change the pin numbers so when the micro:bit tilts left, the motors turn the opposite direction. All that is needed here is to change the 1 s to 0 s and the 0 s to 1 s Now, most of the code is done, all that is left to do is to add code into the else section so when the micro:bit is not doing any of the previous code it will stop all motors Click on the Basic tab, select the show leds block and drag it into the else section

28 Now we need to create a plus sign in the show leds block, to do this, click on the individual boxes until you make a + shape Now we need to make sure the pins we use are turned off. Click on the Advanced tab, then the Pins tab. Select the digital write block and drag it below the previously placed show leds block

29 Repeat the above step, seven more times Now, change the pins on all eight digital write blocks to the micro:bit pins used to control the motors (see image below)

30 You now will have all the code to control the Robotic Arm using a micro:bit You can now download the code to the micro:bit or use the Downloading code to the BBC micro:bit guide on the next page if you are unsure Downloading code to the BBC micro:bit

31 On the bottom left of the PXT editor is a button that says 'Download' - shown below in a red box, click on it to save the code file Click on the downloaded file at the bottom of the browser - select 'Show in Folder' This will open the folder containing all your downloaded files - this will include a file called something like 'microbit-micro-bit-robotic-arm.hex'

32 Right click on the file and choose to copy it (this is ready for the next step), now you need to plug the micro:bit, into your computer Right click on a blank space within the micro:bit folder and choose 'Paste' - it will display a window a bit like the below as it copies the file to the micro:bit. The code has now downloaded, have fun playing with the micro:bit Robotic Arm!!