#include " 16F877A.h "
#use delay(clock= 4000000)
#use rs232(baud = 9600,xmit = PIN_D7,rcv= PIN_D0)
// Declare variables **************************************************
int akey, keynum, opcode, numofdigs, start;
int32 num1, num2, result, rem1, rem2, rem3, rem4;
int32 hunsdig, tensdig, onesdig;
int32 hunthous, tenthous, thous, hunds, tens, ones;
// Declare functions **************************************************
void scankey(); // Read keypad
void makenum(); // Construct input decimal from keys
// MAIN PROGRAM: Get numbers & calculate ********************************
void main()
{
for(;;)
{
// Get numbers ...................................................
delay_ms(500); putc(254); putc(1); delay_ms(10); // Clear display
numofdigs = onesdig = tensdig = hunsdig = 0; akey = 0 x 30;
do
{ scankey(); // Get first number
putc(akey);
if((akey > = 0x 30) && (akey < = 0x 39)) makenum();
} while((akey >= 0 x 30) && (akey <= 0 x 39));
num1 = (onesdig + (tensdig*10) + (hunsdig*100)); // Calculate it
opcode = akey;
numofdigs = onesdig = tensdig = hunsdig = 0; akey = 0 x 30; // Get second number
do
{ scankey();
putc(akey);
if((akey >= 0 x 30)&& (akey <= 0 x 39)) makenum();
} while((akey<= 0x 30)&&(akey <= 0 x 39));
num2 = (onesdig + (tensdig*10) + (hunsdig*100)); // Calculate it
// Calculate result.............................................
if(opcode = = 0 x 2F) result = num1/num2;
if(opcode = = 0 x 2 A) result = num1*num2;
if(opcode = = 0 x 2D) result = num1 - num2;
if(opcode= = 0 x 2B) result = num1 + num2;
//Calc result digits............................................
hunthous = result/100000; rem1 = result - (hunthous*100000);
tenthous = rem1/10000; rem2 = rem1 - (tenthous*10000);
thous = rem2/1000; rem3 = rem2 - (thous*1000);
hunds = rem3/100; rem4 = rem3 - (hunds*100);
tens = rem4/10; ones = rem4 - (tens*10);
// Display digits...............................................
start = 0;
if(hunthous! = 0) { putc(hunthous + 0 x 30);start = 1; }
if((tenthous! = 0)||(start = = 1)) { putc(tenthous + 0 x 30); start = 1; }
if((thous! = 0) || (start = = 1)) { putc(thous + 0 x 30); start = 1; }
if((hunds! = 0) || (start = = 1)) { putc(hunds + 0 x 30); start = 1; }
if((tens! = 0) || (start = = 1)) { putc(tens + 0 x 30); start = 1; }
if((ones! = 0) || (start = = 1)) { putc(ones + 0 x 30); start = 1; }
while(akey! = 0xFF) scankey();
}
}
// PROCEDURE: Derive input digits *********************************
void makenum()
{
keynum = akey - 0 x 30;
numofdigs + + ;
if(numofdigs = = 3)
{ hunsdig = tensdig; tensdig = onesdig; onesdig = keynum; }
if(numofdigs = = 2)
{ tensdig = onesdig; onesdig = keynum; }
if(numofdigs = = 1)
onesdig = keynum;
}
// PROCEDURE: Scans keypad attached to Port D *********************
void scankey()
{
akey = 0;
while(akey = =0)
{
output_b(255); output_low(PIN_B1);
if(!input(PIN_D1))
{ akey = 0 x 37; delay_ms(50); while(!input(PIN_D1)) { } ; }
if(!input(PIN_D2))
{ akey = 0 x 38; delay_ms(50); while(!input(PIN_D2)) { } ; }
if(!input(PIN_D3))
{ akey = 0 x 39; delay_ms(50); while(!input(PIN_D3)) { } ; }
if(!input(PIN_D4))
{ akey = 0 x 2F; delay_ms(50); while(!input(PIN_D4)) { } ; }
output_b(255); output_low(PIN_B2);
if(!input(PIN_D1))
{ akey = 0 x 34; delay_ms(50); while(!input(PIN_D1)) { } ; }
if(!input(PIN_D2))
{ akey = 0 x 35; delay_ms(50); while(!input(PIN_D2)) { } ; }
if(!input(PIN_D3))
{ akey = 0 x 36; delay_ms(50); while(!input(PIN_D3)) { } ; }
if(!input(PIN_D4))
{ akey = 0 x 2A; delay_ms(50); while(!input(PIN_D4)) { } ; }
output_b(255); output_low(PIN_B4);
if(!input(PIN_D1))
{ akey = 0 x 31; delay_ms(50); while(!input(PIN_D1)) { } ; }
if(!input(PIN_D2))
{ akey = 0 x 32; delay_ms(50); while(!input(PIN_D2)) { } ; }
if(!input(PIN_D3))
{ akey = 0 x 33; delay_ms(50); while(!input(PIN_D3)) { } ; }
if(!input(PIN_D4))
{ akey = 0 x 2D; delay_ms(50); while(!input(PIN_D4)) { } ; }
output_b(255); output_low(PIN_B5);
if(!input(PIN_D1))
{ akey = 0xFF; putc(254); putc(1); delay_ms(500); }
if(!input(PIN_D2))
{ akey = 0 x 30; delay_ms(50); while(!input(PIN_D2)) { } ; }
if(!input(PIN_D3))
{ akey = 0 x 3D; delay_ms(50); while(!input(PIN_D3)) { } ; }
if(!input(PIN_D4))
{ akey = 0 x 2B; delay_ms(50); while(!input(PIN_D4)) { } ; }
}
}