Summary of Seven segment display 4 digit For CSS Compiler
This article details a C program for the PIC 16F877 microcontroller designed to create a 4-digit BCD counter with up/down functionality. The system utilizes two switches to increment or decrement a count from 0 to 9999, displaying the result on a common cathode 7-segment display via multiplexing logic.
Parts used in PIC 16F877 Counter Project:
- PIC 16F877 Microcontroller
- Common Cathode 7-Segment Display
- Switch UP (connected to Pin A0)
- Switch DOWN (connected to Pin A1)
- Port C Pins (C0, C1, C2, C3) for digit selection
- Port D for segment data output
- 4MHz Clock Source
#include <16F877.h>
#device adc=8
#fuses NOWDT,HS, NOPUT, NOPROTECT, BROWNOUT, NOLVP, NOCPD, NOWRT, NODEBUG
#use delay(clock=4000000)
#define sw_up pin_a0 // SWITCH UP
#define sw_down pin_a1 // SWITCH DOWN
INT16 COUNT;
int8 A,B,C,D;
//int8 segment[10] ={ 0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90};//common anode
int8 num[10] ={ 0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x27,0x7F,0x6F};//common cathode 0 1 2 3 4 5 6 7 8 9
// 0 1 2 3 4 5 6 7 8 9
VOID HEX_BCD(INT16 VALUE);
void main(){
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_psp(PSP_DISABLED);
setup_spi(FALSE);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
OUTPUT_LOW(PIN_C0);
OUTPUT_LOW(PIN_C1);
OUTPUT_LOW(PIN_C2);
OUTPUT_LOW(PIN_C3);
COUNT=0;
WHILE(true){
IF(!INPUT(SW_up)){IF(COUNT++>9999)COUNT=0;delay_ms(150);}
IF(!INPUT(SW_down)){IF(COUNT --<1)COUNT=9999;delay_ms(150);}
HEX_BCD(COUNT);
OUTPUT_D(NUM[D]); // nuoy
OUTPUT_HIGH(PIN_C0);
DELAY_MS(5);
OUTPUT_LOW(PIN_C0);
OUTPUT_D(NUM[C]); // sib
OUTPUT_HIGH(PIN_C1);
DELAY_MS(5);
OUTPUT_LOW(PIN_C1);
OUTPUT_D(NUM[B]); // Roy
OUTPUT_HIGH(PIN_C2);
DELAY_MS(5);
OUTPUT_LOW(PIN_C2);
OUTPUT_D(NUM[A]); // PHUN
OUTPUT_HIGH(PIN_C3);
DELAY_MS(5);
OUTPUT_LOW(PIN_C3);
DELAY_MS(100);
}
}
void HEX_BCD(INT16 VALUE){
A=0;B=0;C=0;D=0;
while(value>=1000){A++;value-=1000;}
while(value>=100){B++;value-=100;}
while(value>=10){C++;value-=10;}
D=value;
}
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What is the primary function of this code?
The code implements a 4-digit BCD counter that counts from 0 to 9999 using a PIC 16F877 microcontroller. -
How does the user increase the count value?
The count increases when the switch connected to pin_a0 (sw_up) is pressed, provided the current value is less than 9999. -
What happens if the count reaches 9999 and the up switch is pressed again?
The count resets to 0 immediately after reaching 9999. -
How is the down count handled when the value is 0?
If the count is at 1 and the down switch is pressed, it wraps around to 9999. -
Which type of 7-segment display is utilized in this project?
A common cathode 7-segment display is used, as indicated by the specific hex values in the num array. -
What is the purpose of the HEX_BCD function?
This function converts a 16-bit integer value into four separate digits representing thousands, hundreds, tens, and units. -
How are the display digits refreshed continuously?
The main loop cycles through each digit rapidly by setting the corresponding Port C pin high, sending data to Port D, and then turning the pin low. -
What delay is applied to prevent switch bounce?
A delay of 150 milliseconds is implemented after detecting a switch press to debounce the input.
