Differences

This shows you the differences between two versions of the page.

--- user:jcavalu3:portfolio:datacomm2 [2013/11/13 19:27] – created jcavalu3
+++ user:jcavalu3:portfolio:datacomm2 [2013/11/13 19:31] (current) – jcavalu3
@@ Line 1: / Line 1: @@
+=====Binary Counter=====
+In this project, I created a binary counter using the GPIO pins on my raspi.
+The program:
+<code c>
+#include "rpi.h"
+#include <stdlib.h>
+
+int main()
+{
+
+     char *binary, count = 0, holder = 0; // array to hold bit values, variable to check the counter, variable to compare values
+
+     int i; // variable to control loop that sets pins on or off
+
+     binary = (char *)malloc(sizeof(char)*4); // array for binary counter
+
+     if(map_peripheral(&gpio) == -1)
+     {
+         printf("Failed to map the physical GPIO registers into the virtual memory space.\n");
+         return -1;
+     }
+
+     // Define pins 7, 8, 9, and 10 as output
+
+
+     OUT_GPIO(7);
+
+
+     OUT_GPIO(8);
+
+
+     OUT_GPIO(9);
+
+
+     OUT_GPIO(10);
+
+     while(1) // main bulk of the program. Checks value of holder (count) and assigns values to array accordingly
+     {
+         holder = count;
+
+         if((holder - 8) >= 0) // assigns (or does not) first binary bit to array if holder is greater than or equal to 8 (up to 15)
+         {
+             *(binary + 0)  = 1;
+             holder = holder - 8; // subtracts 8 from holder and moves to the next if block
+         }
+         else
+             *(binary + 0) = 0; // if holder not 8 or greater, sets first bit equal to 0
+
+         if((holder - 4) >= 0) // does the same as the previous except considering a value of 4
+         {
+             *(binary + 1) = 1;
+             holder = holder - 4; // subtracts 4 from holder
+         }
+         else
+             *(binary + 1) = 0; // if holder not 4 or greater, sets second bit equal to 0
+
+         if((holder - 2) >= 0) // same as previous, considers value of 2
+         {
+             *(binary + 2) = 1;
+             holder = holder - 2; // subtracts 2 from holder
+         }
+         else
+             *(binary + 2) = 0; // if holder not 2 or greater, sets third bit equal to 0
+
+         if(holder == 1) // pretty self explanatory
+         {
+             *(binary + 3) = 1; // sets fourth and last bit to 1 (on)
+         }
+         else
+             *(binary + 3) = 0; // sets fourth and last bit to 0 (off)
+
+         for(i = 0; i <= 3; i++) // loop which turns on/off GPIO pins according to the values in the array
+         {
+             if( *(binary + i) == 1)
+             {
+                 GPIO_SET = 1 << (i + 7); // sets specific GPIO pin on if value in the memory block of array is 1
+             }
+             else
+                 GPIO_CLR = 1 << (i + 7); // sets specific GPIO pin off if value in the memory block of array is 0
+         }
+
+         count++; // increment count
+
+         if(count > 15) // if block to set value back to 0
+         {
+             count = 0;
+         }
+
+         usleep(1000000); // sleep for one second
+     }
+
+     return 0;
+</code>
+It successfully runs a binary counter which sets the LED's on or off depending on the value stored in the corresponding location of data in the array.

Lab46 Wiki

User Tools

Site Tools

Differences

Page Tools