ZoneMikel's Blog

Ever wonder what happens if you run too much current through a pic ?

Ever wonder what happens if you connect the power supply backwards?

Ever wonder what happens when you accidentally short pos/neg?

You get to see the inside of the chip ! Thats if your eyes where out of the way of the piece of glass like silicone that goes blasting out of the pic.

Needless to say

• the chip does not work anymore
• this could cut you or hit you in the eye
• be careful, wear glasses
• when you start thinking “just a little more power” STOP

Ok i know your saying to yourself “theres already tons of these” but i looked at them and they are long. Anyway i made this to test my ports. Very simple a led connected to port “B” and port “D” on a 877. I know there are better ways to make a led chaser using less pins but im testing my ports (new board) so i need to have a light on each pin to see if it works correctly, im making like a prototyping board and i want to know that all the connections/pins are solid before i make anything out of it.

The best part about this is “bit shifting”, no case/switches or any of that crap. This is the while loop just put it in your main and modify it for your application. It speeds up and slows down, thats what the delay increment is for. before you get into the while loop. If for some reason your using a port that has more than 8 pins you wont be able to store the “bit” variable in a int, try like a int16 etc.

int i =0;
int bit = 0;
int delay = 0;
while(1)
   {

      if (delay > 50){delay = 0;} // if the delay is getting big make it small again so it goes fast
      bit = 1; // set the bit to the rightmost position (pin 1)
      for(i=0;i<8;i++)
      {
         output_d(bit << i); // shift bit to the left "i" times
         output_b(bit << i);
         delay_ms(delay);
      }
      bit = 0b10000000; // put the bit on the far left (pin        for(i=0;i<8;i++)
      {
         output_d(bit >> i); // shift the bit to the right "i" times
         output_b(bit >> i);
         delay_ms(delay);
      }
      delay++; // increment the delay so it goes slower

   }

There were requests for a picture … this was all i could find, it gives you a idea how the display might have been hooked up

3 digit 7 seg display

This was for our intro to engineering project It is a thermometer with a lm34 connected to ra0. It multiplexed 3 “7Segment” led displays connected to the ports, i think the digit was port E and the 7 led’s of the “7Segment” displays were connected to B. You can easily use it on a 877a also if you include the .h for the 877a . I will try and post the schematic but it was all pretty much done on the fly, a schematic was only made for half of it.
It has a lot of functions to do stupid stuff, you dont need them. Any questions post a reply. I would not use this code because i doubt you will have the same setup but it would be a great reference.

/******************************************************************************
/ Program for a pic 16F877 to take analoge input from RA0 in the range
/ of 0- ? volts and display it to a three digit 7 segment Led display. The
/ display is multiplexed and the common cathode/anode is controlled by
/ port E and the actual hex of the number is sent through port B
/
/ by, Michael
/ 10-3-07
/ www.zonemikel.com
/*****************************************************************************/

#include "877.h"
#include <stdio.h>
#include <stdlib.h>

// declare functions
void findnumbers(float temp, int choice);
void sendhex(int number, int digit);
void displaynumbers(int hundreds, int tens, int ones);
int getavgtemp();
void demo(int k);
void showled(float temp, int choice);
void blink();

void main()
{
int i = 0;
int choice = 0; // current menu choice
int16 adc_value; // adc read from AN0 0-1023
float volts; // volts 0-5v
float total = 0; // total for average
float temp = 0; // chop off the .xx
float tempC = 0; // temp in celcius
int scroll[19] = {16,16,16,5,15,14,12,17,16,14,1,11,16,1,0,0,0,0,16};
int k =0;
int n=0;

// tell them what i am
for(k=0;k<20;k++)
{
if (!input(PIN_C1) || !input(PIN_C1)) // did they hit a button ?
{break;} // if so get out of here !
for(i=0; i<200; i++){
for(n=0; n<5; n++)
{
sendhex(scroll[k],1);
sendhex(scroll[(k-1)],2);
sendhex(scroll[(k-2)],3);
}// end for n
}// end for i
}

setup_adc_ports(AN0);
setup_adc(ADC_CLOCK_DIV_8);
set_adc_channel(0);

while(1)
{

if (!input(PIN_C1))
{
choice++;
while(!input(PIN_C1)) // let us see we are piking cX menu choice
{displaynumbers(11, 0, choice);}
output_e (0x00); // turn off digit of 7 seg display if not it continues
// to display the last digit of whatever u had b4
}
if (!input(PIN_C3))
{
choice--;
while(!input(PIN_C3)) // let us see we are piking cX menu choice
{displaynumbers(11, 0, choice);}
output_e (0x00); // turn off digit of 7 seg display if not it continues
// to display the last digit of whatever u had b4
}

switch(choice)
{
case 0:
// get the average and store it in var temp in F
total = 0;
for (i=0; i<20; i++)
{

findnumbers(temp, choice);
adc_value = read_adc();
volts = (float)(adc_value * 4.8)/1023.0;
//delay_us(100);
total += volts;
}

temp = ((total/20)*100);
showled(temp,choice); // turn on color led for hot/med/cold/freezing
// display temp on 3 digit 7seg led, turn on light to do with temp
for (i=0; i<50; i++)
{if (!input(PIN_C1) || !input(PIN_C3))
{break;}
findnumbers(temp, choice);}

break;

case 1:
// get the average and store it in var temp in C
total = 0;
for (i=0; i<20; i++)
{
findnumbers(tempC,choice);
adc_value = read_adc();
volts = (float)(adc_value * 4.8)/1023.0;
//delay_us(100);
total += volts;
}

tempC = ((((total/20)*100)-32)/1.8);
// display temp on 3 digit 7seg led, turn on light to do with temp
showled(tempC,choice); // turn on color led for hot/med/cold/freezing
// display temp on 3 digit 7seg led, turn on light to do with temp
for (i=0; i<50; i++)
{if (!input(PIN_C1) || !input(PIN_C3))
{break;}
findnumbers(tempC, choice);}
break;

case 2:
// send information to serial (uart) for commuication with other device
for (i=0; i<3; i++)
{
if (!input(PIN_C1) || !input(PIN_C1)) // did they hit a button ?
{break;} // if so get out of here !
if (i == 2){output_high(PIN_E0);}
if (i == 1){output_high(PIN_E1);}
if (i == 0){output_high(PIN_E2);}
delay_ms(100);
output_b (0b1000000);
delay_ms(100);
output_b (0b0100000);
delay_ms(100);
output_b (0b0010000);
delay_ms(100);
output_b (0b0001000);
delay_ms(100);
output_b (0b0000100);
delay_ms(100);
output_b (0b0000010);
delay_ms(100);
output_b (0b0000001);
delay_ms(100);
}
total = 0;
for (i=0; i<20; i++)
{
adc_value = read_adc();
volts = (float)(adc_value * 4.8)/1023.0;
//delay_us(100);
total += volts;
}

temp = ((total/20)*100);
delay_ms(200);
printf("\f ADC0: %f temp: %f total: %f i: %i", volts, temp, total, i);
delay_ms(200);
break;

case 3:
// a colorful placeholder thing, flashes lights and counts
demo(5);
break;

case 4:
// something to display on the seven seg display
// super pic 1000 is displayed

for(k=0;k<20;k++)
{
if (!input(PIN_C1) || !input(PIN_C1)) // did they hit a button ?
{break;} // if so get out of here !
for(i=0; i<100; i++){
for(n=0; n<5; n++)
{
sendhex(scroll[k],1);
sendhex(scroll[(k-1)],2);
sendhex(scroll[(k-2)],3);
}// end for n
}// end for i
}// end for k

break;

case 5:
blink();
break;

default: // out of bounds set to 0 (zero) again
choice = 0;
break;
}
}// end of while(1)
}// end of main

// blinks led of temp range
void showled(float temp, int choice)
{
if (choice == 1){temp = (((temp*9)/5)+32);}
output_d (0x00); // all off

if (temp > 0 && temp < 50)
{
output_high(PIN_D0);
}
if (temp > 50 && temp < 70)
{
output_high(PIN_D1);
}
if (temp > 70 && temp < 90)
{
output_high(PIN_D2);
}
if (temp > 90)
{
output_high(PIN_D3);
}
}
// function to find number
void findnumbers(float temp, int choice) // get hundreds tens ones (for seven seg display)
{

int inttemp = 0; // temp with decimal removed
int hundreds = 0; // hundreds position
int tens = 0; // tens position
int ones = 0; // ones position
int ForC; // f or c temp
if (choice == 0){ForC = 13;}
if (choice == 1){ForC = 11;}
if (choice == 3){ForC = 16;} // dont do this print nothing
if (temp < 100)
{
inttemp = temp;

hundreds = (inttemp/100)%(10);
tens = (inttemp/10)%(10);
ones = (inttemp%10);
displaynumbers(tens, ones, ForC);
}

if (temp > 100)
{
inttemp = temp;

hundreds = (inttemp/100)%(10);
tens = (inttemp/10)%(10);
ones = (inttemp%10);
displaynumbers(hundreds, tens, ones);
}
if (temp > 255)
{
displaynumbers(12, 0, 1);
}

}

// this converts a number to the desired high/low combination
// for the 7 seg led display
void sendhex(int number, int digit)
{
//dot 	g 	f 	e 	d 	c 	b 	a
// 0 	0 	0 	1 	1 	1 	1 	1 	1 	3F
output_e (0x00);
// send hex to port b to make number
if (number == 0){output_b (0x3F);} // output 0 to port b 11000000
if (number == 1){output_b (0x6);} // 1 11111001
if (number == 2){output_b (0x5B);} // 2 10100100
if (number == 3){output_b (0x4F);} // 3
if (number == 4){output_b (0x66);}
if (number == 5){output_b (0x6D);}
if (number == 6){output_b (0x7D);}
if (number == 7){output_b (0x07);}
if (number == 8){output_b (0x7F);}
if (number == 9){output_b (0x67);}
// all these need to be fixed for common cathode
if (number == 10){output_b (0x88);} // A
if (number == 11){output_b (0x39);} // C // cathode 11000110 00111001
if (number == 12){output_b (0xF9);} // E // for cathode   11111001
if (number == 13){output_b (0x71);} // F // 10001110 01110001
if (number == 14){output_b (0x73);} // P // 10001100 01110011
if (number == 15){output_b (0x3E);} // U // 01111110 00111110
if (number == 16){output_b (0x0);} // nothing at all
if (number == 17){output_b (0x50);} // lower case r  01010000

//turn on the digit(send high to common cathode via transistor)
if (digit == 3){output_high(PIN_E0);}
if (digit == 2){output_high(PIN_E1);}
if (digit == 1){output_high(PIN_E2);}
delay_us(100);

}

// this just sends the right number to the right digit if its less than
// 100 it will use the extra digit to display a F eg. 45F
void displaynumbers(int hundreds, int tens, int ones)// send to led
{
int i = 0;

// if its more than 100 display eg. 102 else display eg. 67F
if(hundreds >= 0) // always do this loop when u dont want F
{
for(i=0; i<200; i++)
{
sendhex(hundreds, 3);
sendhex(tens, 2);
sendhex(ones, 1);
}
}else{
for(i=0; i<200; i++)
{
sendhex(tens, 3);
sendhex(ones, 2);
sendhex(12, 1); // 12 is F
}
}
}
void demo(int k) // do neat stuff
{
int i = 0;

for (i = 0; i < 255; i++)
{
if (!input(PIN_C1) || !input(PIN_C3)) // did they hit a button ?
{break;}
output_high(PIN_D0);
delay_ms((k*i)/200);
output_low(PIN_D0);
//findnumbers(k); // k is normally unchanging.
output_high(PIN_D1);
findnumbers(i,3);
delay_ms((k*i)/100);
output_low(PIN_D1);
//
output_high(PIN_D2);
//findnumbers(i);
delay_ms((k*i)/200);
output_low(PIN_D2);
//
output_high(PIN_D3);
//findnumbers(i);
delay_ms((k*i)/100);
output_low(PIN_D3);

delay_ms((k*i)/100);
// reverse

output_high(PIN_D3);
//findnumbers(i);
delay_ms((k*i)/200);
output_low(PIN_D3);
//
output_high(PIN_D2);
//findnumbers(i);
delay_ms((k*i)/100);
output_low(PIN_D2);
//
output_high(PIN_D1);
//findnumbers(i);
delay_ms((k*i)/200);
output_low(PIN_D1);
//
output_high(PIN_D0);
//findnumbers(i);
delay_ms((k*i)/100);
output_low(PIN_D0);
}
}

void blink()
{
int i = 0;
while(1)
{
if (!input(PIN_C1)) // get out if they hit button one
{break;}

if (!input(PIN_C3)) // if they hit button two incrament i
{i++;}
findnumbers(i,3);
// lights high
output_high(PIN_D3);
output_high(PIN_D2);
output_high(PIN_D1);
output_high(PIN_D0);
delay_ms(i);
output_low(PIN_D2);
output_low(PIN_D1);
output_low(PIN_D0);
output_low(PIN_D3);
delay_ms(i);

}
}

/* table so i dont have to calculate again !!!
For common Cathode :

Hex Number

Seven Segment conversion

Seven Segment equivalent
dot 	g 	f 	e 	d 	c 	b 	a
0 	0 	0 	1 	1 	1 	1 	1 	1 	3F
1 	0 	0 	0 	0 	0 	1 	1 	0 	06
2 	0 	1 	0 	1 	1 	0 	1 	1 	5B
3 	0 	1 	0 	0 	1 	1 	1 	1 	4F
4 	0 	1 	1 	0 	0 	1 	1 	0 	66
5 	0 	1 	1 	0 	1 	1 	0 	1 	6D
6 	0 	1 	1 	1 	1 	1 	0 	1 	7D
7 	0 	0 	0 	0 	0 	1 	1 	1 	07
8 	0 	1 	1 	1 	1 	1 	1 	1 	7F
9 	0 	1 	1 	0 	0 	1 	1 	1 	67

For common Anode :

Hex Number

Seven Segment conversion

Seven Segment equivalent
dot 	g 	f 	e 	d 	c 	b 	a
0 	1 	1 	0 	0 	0 	0 	0 	0 	C0
1 	1 	1 	1 	1 	1 	0 	0 	1 	F9
2 	1 	0 	1 	0 	0 	1 	0 	0 	A4
3 	1 	0 	1 	1 	0 	0 	0 	0 	B0
4 	1 	0 	0 	1 	1 	0 	0 	1 	99
5 	1 	0 	0 	1 	0 	0 	1 	0 	92
6 	1 	0 	0 	0 	0 	0 	1 	0 	82
7 	1 	1 	1 	1 	1 	0 	0 	0 	F8
8 	1 	0 	0 	0 	0 	0 	0 	0 	80
9 	1 	0 	0 	1 	1 	0 	0 	0 	98
*/