PIC16F877A development board digital tube counter experiment-EEWORLD

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//*******************Electronic Park PIC16F877A development board digital tube counter experiment*****************

//CKP=0; Idle is low level

//CKP=1; Idle is high level

//STAT_CKE=0; SDO trailing edge sampling

//STAT_CKE=1; SDO leading edge sampling

//STAT_SMP=0; //Sampling input data in the middle of data output time

//STAT_SMP=1; //Sampling input data at the end of data output time

//RC3/SCK connects to 74595 shift clock pin 11

//RC5/SDO connects to 74595 data input pin 14

//RC4/SDI connects to 74595 latch clock pin 12

//When TMR0 is used as a timer, timer clock = system clock/4

//When writing TMR0, a 2-cycle delay will be generated. If the pre-divider is not used, it can be compensated by setting the initial value

//For example, when 200 clock cycles are required, TMR0=256-200+2=58

//Use TMR0 to realize dynamic scanning of digital tubes, lighting up one digital tube every 1ms

//mcu: PIC16F877A 4MHz Electronic Park PIC16F877A development board

//December 23, 2010 19:22:30

//***************************************************************************

#include

__CONFIG(HS&WDTDIS&LVPDIS&PWRTEN);

//HS oscillation, disable watchdog, low voltage programming shutdown, start delay timer

fly disbuf[8];

uint count=0;

uchar time_ok=0;

//********************Function definition*********************

void delay1ms(uint DelayTime);

uchar spi_write_read(uchar dd);

void led_display(void);

void decimal_bcd_16bit(uint cnt);

//*************** Main program************************

void main(void)

{

SSPM3=0;

SSPM2=0;

SSPM1=0;

SSPM0=0; //spi master mode, clock is Fosc/4

CKP=0; //Idle is low level

STAT_CKE=1; //SDO leading edge sampling

STAT_SMP=0; // Sample input data in the middle of data output time

TRISC3=0; //RC3/SCK is output

TRISC5=0; //RC5/SDO is output

TRISC4=0; //RC4/SDI is output (when the SDI pin is not used, it can be set to output for normal IO use)

RC4=0;

SSPEN=1; //Enable MSSP module, enable spi or iic

PSA=1; //The pre-divider is assigned to WDT (TMR0 clock is not divided)

T0CS=0; //Set to timing mode

TMR0=256-200+2; //timing 200 clocks

GIE=1; //General interrupt enabled

T0IE=1; //TMR0 interrupt enable

delay1ms(10);

while(1)

{

if(time_ok)

{

time_ok=0;

count=count+1;

decimal_bcd_16bit(count);

}

//****************spi bus sends and receives data****************

uchar spi_write_read(uchar dd)

{

flying buff;

SSPBUF=dd;

while(!STAT_BF); //Wait for data to be sent and received

buf=SSPBUF;

return (buf); //Return the received data

}

void led_display(void)

{

const float smg[]={0x0a,0xfa,0x8c,0xa8,0x78,0x29,0x09,0xba,0x08,0x28,0x00,};

// 0 1 2 3 4 5 6 7 8 9 all

const uchar smg_bit[]={0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80,0xff,};

static uchar st=0;

RC4=0;

spi_write_read(smg_bit[st]);

spi_write_read(smg[disbuf[st]]);

RC4=1;

st=(++st)%8;

}

void decimal_bcd_16bit(uint cnt)

{

disbuf[4]=(cnt/1000)%10;

cnt=cnt%1000;

disbuf[5]=(cnt/100)%10;

cnt=cnt%100;

disbuf[6]=cnt/10; //divide by 10

disbuf[7]=cnt%10; //Get the unit digit

disbuf[0]=disbuf[4];

disbuf[1]=disbuf[5];

disbuf[2]=disbuf[6];

disbuf[3]=disbuf[7];

}

//*********************Interrupt service routine******************

void interrupt isr(void)

{

static uchar time_con1=0;

static uint time_con2=0;

if(T0IE&&T0IF) //Judge whether it is TMR0 interrupt

{

T0IF=0; // Clear TMR0 interrupt flag (must be cleared by software)

TMR0=TMR0+58; //Re-initialize TMR0

if(++time_con1>=5) //Timer 1ms each time

{

time_con1=0;

led_display();

}

if(++time_con2>=500) //Counter increments by 1 every 0.1s

{

time_con2=0;

time_ok=1;

}

//********************Delay n*1ms 12MHz*****************

void delay1ms(uint DelayTime)

{

uint temp;

for(;DelayTime>0;DelayTime--)

{

for(temp=0;temp<270;temp++)

{;}

}

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