HOW to Achieve Light Adjustment with KidsIOT

Flow

Assembly

Required:

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

Step 7

Completed!

Wiring Diagram

Test Code

Open KidsBlock and connect to the board, click File –> Load from your computer.

Choose D:\Code\2.Code_kidsIOT to open 4.3Brightness_adjustment.sb3

Click  to connect to port and then click .

Explanation

Code Blocks

Conceive:

1. Initialization

   Set the pin of the white LED and the potentiometer module, initialize the serial monitor.

   

2. Main Code

   Loop: Read the value output by the potentiometer, and set the value as the duty cycle of the LED module to control its brightness.

   

   
   

   Build blocks:

   ① 

   ② Put  into “forever” and set pin to IO3.

   ③ Add a  (map block).

   

   

   

   Q ： The brightness value of LED is 0 ~ 255, while the output analog value of potentiometer is 0 ~ 4095. So how to control the brightness via the potentiometer?

   A ： We use map block to map the output range to the brightness range.

   
   

   Q ： What is MAP?

   A ： In mathematics, MAP is the term for a relationship between two sets of elements that “correspond” to each other.

   Set: a whole consisting of one or more defined elements.

   There is a correspondence between Set A and B. For every Element a in Set A, there is always a unique element b corresponding to it in Set B, which is called map A to B.

   The concept of mapping is not only used in mathematics, but in computer science. In a computer program, mapping is a way to map each element in one set to a unique element in another.

   We assume that the output analog values of the potentiometer is A, and the brightness range is B. We map values in A to B, so the output value will correspond to a unique brightness value. This kind of one-to-one mapping enables the potentiometer to directly adjust the brightness.

   

   

   Five values need to be set in this map block:

   ​ (1): the value to be mapped;

   ​ (2 & 3): the range of the value to be mapped;

   ​ (4 & 5): the range after mapping.

   Set the mapped value as the analog value read by IO34: Drag  to the first box and set pin to IO34.

   

   
   

   Set the range of the value to be mapped: here is the output range of the potentiometer(0 ~ 4095), so we set the second and third value to 0 and 4095 respectively.

   

   
   

   Set the range after mapping: here is the brightness value range of LED(0 ~ 255), so we set the forth and fifth value to 0 and 255 respectively.

   

   ④ Put the map block into the PWM output as the duty cycle of the white LED module, so that we can control the brightness via the potentiometer.