Button experiment:
Purpose: Control other components by pressing the button
experiment one
K1 ~ K4 controlled LED shift
OBJECTIVE: To press the independent buttons K1 to K4, the LED shift display connected to the P0 and P2 ports can be controlled up and down, respectively.
# include
// Use the library function of the chip
# include
#define uchar unsigned char
#define uint unsigned int
SBIT LED1 = P0 ^ 0;
SBIT LED2 = P0 ^ 1;
SBIT LED3 = P0 ^ 2;
SBIT LED4 = P0 ^ 3;
SBIT K1 = P1 ^ 0;
SBIT K2 = P1 ^ 1;
SBIT K3 = P1 ^ 2;
SBIT K4 = P1 ^ 3;
Void delayms (uint x)
{
Uchar i;
While (x -)
For (i = 0; I < 120; i ++);
}
void main ()
{
P1 = 0xFF;
P0 = 0xFF;
While (1)
{
LED1 = k1;
LED2 = k2;
IF (k3 == 0)
{
While (k3 == 0);
LED3 = ~ LED3;
}
IF (k4 == 0)
{
While (k4 == 0);
LED4 = ~ LED4;
}
DELAYMS (10);
}
}
void main ()
{
P1 = 0xFF;
P0 = 0xFF;
While (1)
{
LED 1 = K1;
// k1 = 1, the lamp is off; K1 = 0, the light is on
// LED1, 2, directly controlled by the button, the button status is the state of the lamp
// LED3, 4, indirect control by the button, press the button for the first time
IF (k3 == 0) // Press K3, K3 = 0
{
While (k3 == 0);
/ / Keep the status of the lamp, wait for the release button; after the button is released, the next instruction is executed, that is, the opposite state.
LED3 = ~ LED3;
/ / Realize the opposite state of the lamp, double button status switch
}
IF (k4 == 0)
{
While (k4 == 0)
LED4 = ~ LED4;
}
DELAYMS (10);
}
}
Focus
-While (1) and while (1); (with a semicolon) -
While (1) {...}: Yes, let the microcontroller have been executing {...}, ** Prevent procedures from running **, usually used for the main program, ensure that the program continues to execute
While (1);
: Yes, it is an instruction, which allows the single-chip to stop in this position, generally used to detect the interrupt, only the CPU receives the interrupt command, will only jump out of the While (1), enter the interrupt service subroutine;
WHLIE (1) The essence is a dead cycle, and the instructions in While (1) will continue to be repeated, unless there is interruption, while (1); can be seen as a while (1) {// empty instruction}, it is empty instruction ,
* The microcontroller stops in this line code *
- High and low levels of buttons -
High low level of the button
Obviously: We are valid at high power. When you are not pressed, it is high level, 1; when K1 = 1, the lamp is destroyed; from P0, P1 pin initialization can also be seen.
Experiment three
K1 ~ K4 packet controlled LED
Experimental Content: 4 different operations are performed on the LEDs after the bond is drawn.
# include
#define uchar unsigned char
#define uint unsigned char
Void delayms (uint x)
{
Uchar t;
While (--X)
For (t = 0; t < 120; t ++);
}
void main ()
{
Uchar K, T, Key_State; // Define variables, and keyboard
P0 = 0xFF; // Initialization P0, P1 pin
P1 = 0xFF;
While (1)
{
T = P1;
// Record the P1 initial value
IF (t! = 0xff) ////
{
DELAYMS (10);
IF (t! = p1) Continue; // Check the button again
Key_State = -t >> 4; // get a 4-digit button value,
// By the mode XXXX1111 (one bit is 0, the other is 1)
/ / Becomes a pattern 0000xxxx (one bit in X is 1, the other is 0)
K = 0;
// Check 1 location, accumulate the button number K
While (key_state! = 0)
{
K ++;
Key_State >> = 1;
}
/ / 4 processing according to the button number K
// (The current situation is within the cyclic body, the instructions in Switch will be judged and executed)
Switch (k)
{
Case 1: IF (p0 == 0x00) P0 = 0xff; // 1111 1111
P0 << = 1; // p0 left shift a 1111 1110 left shift
DELAYMS (200);
Break;
Case 2: p0 = 0xf0; Break; // Light [above] 4
Case 3: p0 = 0x0f; break; // Light [below] 4
// Recommended knowledge points: common cathode or anode, and pins
Case 4: p0 = 0xff; // Close all
}
}
}
}
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