Diff: main.cpp

Revision:

9:77ae456366f7

Parent:

8:2b61de165543

Child:

10:90cc064f7082

--- a/main.cpp	Mon Apr 13 17:11:10 2015 +0000
+++ b/main.cpp	Wed Apr 22 10:49:08 2015 +0000
@@ -1,11 +1,13 @@
 //project to include preamble, addressing, post amble, crc error control.
 
+//after sending - set clock to 0, set timer and check clock pin - if clock pin goes high read in response - 4 bit ack?
+
 #include "mbed.h"
 #include "stdio.h"
 
 #define MAX 100 //set the max size of the character data storage array
 #define BYTE 128
-#define NIBBLE 8 //used to set binary position of msb
+#define NIBBLE 16 //used to set binary position of msb
 #define PREAMBLE 0x7E //preamble of 01111110
 #define POSTAMBLE 0x81 //postamble of 10000001
 //addressing 1st 4 bits indicate the network, 2nd 4 bits indicate the station id
@@ -56,6 +58,20 @@
         if(data[i] == '\n')
         {
             sent = 1;
+            //pad out sent data with 0's so crc is sent for all data.
+            while( (i%3) != 0)
+            {
+                //pad data with 0's
+                data[i] = 0x00;
+                send_byte(data[i], BYTE);
+                //store 0's into temp variable for crc calculation
+                crc_temp <<= 8;
+                crc_temp += data[i];
+                i++;       
+            }
+            //calculate and send crc
+            crc_value = calculate_crc(crc_temp);
+            send_byte(crc_value, NIBBLE);
         }
         //string still has data send next byte and handle crc.
         else
@@ -63,13 +79,13 @@
             //send the data
             send_byte(data[i], BYTE);
             //store the sent data into temp variable for crc calculation
-            crc_temp << 8;
+            crc_temp <<= 8;
             crc_temp += data[i];
             //increment array pointer
             i++;
             //wait until i increments and then check to see if 3 bytes have been sent
             //i here is the actual count of bytes sent, not the array location that was just sent
-            //this also avoids sending a crc nibble after no data has been sent - can we figure logic for sending last crc if data not divisible by 3?
+            //this also avoids sending a crc nibble after no data has been sent
             if( (i % 3) == 0)
             {
                 //calculate and send crc
@@ -77,6 +93,7 @@
                 send_byte(crc_value, NIBBLE);
                 //zero out crc temp variable
                 crc_temp = 0;
+                crc_value = 0;
             }
         }
     }
@@ -121,10 +138,10 @@
 unsigned char calculate_crc(int crc_bytes)
 {
     //temp variable
-    unsigned char temp
+    unsigned char temp;
     
-    //shift crc over 4 spots
-    (crc_bytes << 4);
+    //shift crc over 5 spots
+    crc_bytes <<= 5;
     
     //return remainder
     temp = crc_bytes % CRC;