Overview
Make a rotating billboard, which can display the letters (of some English word) one by one, such as mCookie, on the screen will m>mC>mCo>mCoo>mCook>mCooki>mCookie be displayed successively.
Suitable kits: mCookie202, mCookie302
Module Bill
Modules
Other Equipment
- USB cable*1
- Sensor cable*1
- Sensor shell*1
- Lego or other fixation structures
Module Setup
- Assemble the modules and sensors together:
- Stick the red core module, USB upload module and green extension module together;
- Connect the servo connector to pin 6/7 of Hub;
- Connect the servo to pin 1 (the below three pins) of servo connector;
- Connect OLED to IIC pin of Hub;
- Plug one end of USB cable into the USB upload module, and connect the other end to computer;
Programming
Required Program Blocks
Programming Thought
Execute the display program and servo rotating program once for each step. You students look for what principles it has. In this way, they should be execute repeatedly many times, how to simplify the program?
Learn the new program blocks: "Function" program block
Design the function, input the content to display, and the function will control the OLED to display it, and control the servo to rotate a certain angle. Implement the display through continuously calling the function and inputting different parameters.
Start to Program
1. Function Prepare
Define a function named motion_a, with the parameter text. Set the parameter to char string.
2. Design the internal program of the function
The servo of pin 6 rotates to angle servo, with the rotation speed of 30°per second. Variable servo adds 10 ( so that the next time to execute the function, the servo angle will be 10°larger than this time). Pay attention to that the function preparation can’t be connected with other program blocks.
3. Execute the function
Declare a variable servo for storing the servo angle. Set servo to 60. Execute function motion_a to display "mCookie" out slowly.
- Test the result
- After uploading the program, along with the beginning of servo rotation, "mCookie" will be displayed gradually on OLED.
Q: Now the billboard can display the letters mCookie one by one while rotating, how to make the billboard remove the letters also one by one while rotating back?
A: You can write the letters backward. And at the same time, the servo should rotate back, and the variable value reduces. You can add a new function to control the removing of letters on OLED, and make the servo rotate back.
Define a function named motion_b with a parameter text. The servo of pin 6 rotates to the angle servo, with the rotation speed of 100° per second, and the parameter text is displayed on OLED.
Variable servo reduces 10 ( so that the next time when the function is to be executed, the servo angle is 10° less than this one).
Execute function motion_b, to remove the letters "mCookie" one by one. .
Technical Specification
- For details about servo please refer to Servo.
Related Cases
Q&A
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