Zigbee learning path (Part 3): button control

I. Introduction

Through the previous experiment, I believe everyone has a certain understanding of cc2530 program writing. This time we will operate and experiment with the key module on cc2530.

2. Principle Analysis

Let's first look at the schematic diagram of the button:

According to the schematic diagram, we can conclude that the value is 0 when the button is not pressed, because it is grounded. Therefore, when the button is about to be pressed, the input values ​​of BUT1 and BUT2 are 1. When they are detected to be 1, the button is in the pressed state. Because the default state of P0DIR is input, there is no need to configure the IO register. When the button is pressed, the state of the LED changes to verify the experiment.

III. Procedure

#define LED1 P1_0 //LED1 is controlled by P1_0 port

#define LED2 P1_1 //LED2 is controlled by P1_1 port

#define LED3 P1_4 //LED3 is controlled by P1_4 port

#define KEY1 P0_4 //KEY1 is the control port of P0_4

/***************** Function name: Delayms Function description: millisecond delay Input parameter: xms: delay time, such as i=xms, that is, delay i milliseconds Output parameter: none Return value: none *********************/

void Delayms(uint xms) { uint i,j; for(i=xms;i>0;i--) for(j=587;j>0;j--); }

/ Function name: InitLed Function description: LED IO initialization Input parameter: none Output parameter: none Return value: none *************/

void InitLed(void)

{ P1DIR |= 0xff; //P1 port is defined as output    

LED1 = 1; //LED1 is off    

LED2 = 1;    

LED3 = 1; }

/******************** Function name: KeyScan Function description: Key detection function Input parameter: none Output parameter: none Return value: 0: No key is pressed 1: Key is pressed **************************/

uchar KeyScan(void)

{    

if(KEY1==0)    

{ Delayms(2); //Delay debounce        

if(KEY1==0)        

{ while(!KEY1); // Release detection, if the key is pressed, it will stop at this statement      

       return 1; //A button is pressed }   

  } return 0; //No button pressed }

/************************* Function name: main Function description: KEY test (for general IO input/output) Input parameter: NONE Output parameter: NONE Return value: NONE **************************/

void main(void) { InitLed(); //Call initialization function    

while(1)    

{ if(KeyScan())       

  {LED1=~LED1; //Button changes LED status            

LED2=~LED2;            

LED3=~LED3; }   

} }

IV. Conclusion

Through this experiment, we learned how to use buttons to control the peripherals of cc2530, and use the keyboard scanning function to detect changes in button status. The function calls a delay function for delay debouncing to increase system stability. However, continuous detection will occupy the CPU's working time. The next lecture will introduce a better way.