51 MCU Learning - 1 - Light up the first LED-EEWORLD

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Light up the LED

principle:

LED Schematic

The LED light of this single chip is a light emitting diode, which can only pass in one direction. In the figure, the cathode of the LED is connected to the IO port, and the anode is connected to VCC, that is, the power supply, which is a high level. Under normal circumstances, the P2 port outputs a high level by default, so you only need to make the P2 port output a low level.

Code:

#include

sbit led=P2^0; //Through bit definition, let led represent port P20

void main()

{

while(1)

{

led=0; //Set P20 to low level

}

Summarize:

Knowledge points:

Set pin sbit name = Px^x (IO port)

Make the IO port corresponding to the target LED light output low level

expand:

You can also directly assign values to all IO ports of P2. That is, 1111 1111 from high to low corresponds to 1 to 8 LED lights from left to right. If you want to light it up, set the 1 in that position to 0, and then convert it to hexadecimal. For example, to light up all LEDs, set P2=0x00.

At this time, you may see movement on the digital tube, which is normal because P2^2, 3, 4 correspond to the bit selection of the digital tube.

Reference address：51 MCU Learning - 1 - Light up the first LED

Previous article：51 MCU Learning——2--LED Flashing + Flowing Water
Next article：51 MCU Study Notes [Part 3] - Digital Tube Experiment

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