Diff: main.cpp
- Revision:
- 0:906202f8e2f2
- Child:
- 1:2bba0fcfda85
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Thu Apr 16 14:13:01 2015 +0000
@@ -0,0 +1,257 @@
+#include "mbed.h"
+#include "stdio.h"
+#include "C12832.h"
+
+#define MAX 100 //set the size of the character data storage array
+#define BYTE 8
+#define NIBBLE 4 //used to set size of data read
+#define PREAMBLE 0x7E //preamble of 01111110
+#define POSTAMBLE 0x81 //postamble of 10000001
+#define ADDRESS 0x11 //address of 00010010 - network of 1, id of 2.
+#define NETWORK 0x10 //network portion of the address
+#define ID 0x02 //id portion of the address
+#define BROADCAST 0x00 //address of 00000000
+//multicast using 4bit address / 4 bit network. network = 4 msb, address = 4 lsb. broadcast = all 0's. multicast = network id & address of 0's.
+#define CRC 0x13 //crc of 10011 or x^4+x+1 or crc-5
+
+
+C12832 lcd(p5, p7, p6, p8, p11); //LCD structure
+DigitalOut myled(LED1), myled2(LED2), myled3(LED3), myled4(LED4); //variables to access the four blue leds
+DigitalIn clock_pin(p21), serial_in(p22); //clock pulse input and data input pins
+Timer t; //timer for pausing after postamble received before displaying data
+unsigned char temp, data[MAX], crc_calc; //temp byte storage, storage array, transmitted crc value
+unsigned char preamble, address, i, j, k; //increment variables
+unsigned char data_flag, rflag, d_flag, done, temp_data; //data flags
+int crc_passed = 0; //crc flag
+int temp_crc = 0; //stores values for crc check.
+
+//funtion prototypes
+void check_byte(int value); //stays inside the function until the received byte matches the value passed into the function (PREAMBLE)
+int check_abyte();//after preamble received checks the next byte for address. Returns 1 if address received matches ADDRESS, BROADCAST, or multicast; 0 if not.
+int read_byte(int size); //reads received data and returns it a byte at a time.
+int check_crc(int temp_crc, unsigned char crc_calc); //double checks the sent crc value - data sent without error.
+
+//Improvements
+//if crc correct display correct crc
+//if crc correct send ACK(1) to Master
+//if crc wrong, display incorrect crc
+//if crc wrong, send NoACK(0) to Master
+//if crc wrong adjust for retransmit
+
+
+int main()
+{
+
+ //turn off leds
+ myled = 0;
+ myled2 = 0;
+ myled3 = 0;
+ myled4 = 0;
+
+ //initialize variables
+ i = 0;
+ d_flag = 0;
+ done = 0;
+ crc_passed=0;
+
+
+ while(!d_flag)
+ {
+ //clear lcd screen, print current build message
+ lcd.cls();
+ lcd.locate(0,3);
+ lcd.printf("Waiting for Preamble");
+ //read input clock pulse and data checking for preamble.
+ //preamble while loop
+ check_byte(PREAMBLE);
+
+ //clear lcd screen, print current build message
+ lcd.cls();
+ lcd.locate(0,3);
+ lcd.printf("Preamble Received");
+
+ //preamble received check address (next byte), returns to preamble check if not addressed to station
+ if(check_abyte())
+ d_flag = 1;
+ }
+
+ while(!done)
+ {
+ //store data into character array if crc checks.
+ data[i] = 0; //initialize current array position to zero
+ temp_data = read_byte(BYTE); //store successfully transmitted data
+
+ //check for postamble
+ if(temp_data == POSTAMBLE)
+ {
+ //break out of while loop - data finished sending
+ done = 1;
+ //clear lcd screen, print current build message
+ lcd.cls();
+ lcd.locate(0,3);
+ lcd.printf("Postamble Received");
+ }
+
+ //store data in character array if not postamble - check crc when appropriate
+ else
+ {
+ data[i] = temp_data;
+ i++; //increment array position
+ //store the sent data into temp variable for crc calculation
+ temp_crc << 8;
+ temp_crc += temp_data;
+ //wait until i increments and then check to see if 3 bytes have been received
+ if( (i % 3) == 0)
+ {
+ //check crc
+ crc_calc = read_byte(NIBBLE);
+ if(check_crc(temp_crc, crc_calc))
+ {
+ crc_passed=1;
+ lcd.cls();
+ lcd.locate(0,3);
+ lcd.printf("Data passes CRC verification");
+ }else{
+ lcd.cls();
+ lcd.locate(0,3);
+ lcd.printf("Data fails CRC verification");
+ }
+ //zero out crc temp variable
+ temp_crc = 0;
+ }
+ }
+ }
+ //pause after displaying postamble received and then display data.
+ t.start();
+ //wait until the timer has reached the set time.
+ while(t.read_ms() < 1000)
+ {
+
+ }
+ //stop and reset the timer
+ t.stop();
+ t.reset();
+ if(crc_passed){//if crc passes display data, send ACK
+ //clear debugging messages - and reset lcd to original position before printing data.
+ //send ACK
+ lcd.cls();
+ lcd.locate(0,3);
+ lcd.printf("Received: ");
+ for(k=0; k<=i; k++)
+ lcd.printf("%c", data[k]);
+ }else{//if crc fails, send NOACK
+ //send NoACK
+ }
+}
+
+void check_byte(int value)
+{
+ data_flag = 1;
+ temp = 0;
+ rflag=0;
+ //while loop
+ while(!rflag)
+ {
+ //read in data if clock is 1 and data flag is 1
+ if(clock_pin && data_flag)
+ {
+ //data is left shifted into our temporary variable.
+ //each new data bit is moved into the least significant bit after the rest of the bits are shifted to the left
+ //data must be sent from the other microcontroller shifted out from the most significant bit to the least significant bit.
+ temp = (temp << 1) + serial_in;
+ data_flag = 0;
+ if(temp == value)
+ rflag = 1;
+ }
+ //when clock returns to low - reset data flag to accept the next bit.
+ if(!clock_pin && !data_flag)
+ data_flag = 1;
+ }
+}
+
+int check_abyte()
+{
+ j = 0;
+ temp = 0;
+ rflag=0;
+ //while loop
+ while(j<8)
+ {
+ //read in data if clock is 1 and data flag is 1
+ if(clock_pin && data_flag)
+ {
+ //data is left shifted into our temporary variable.
+ //each new data bit is moved into the least significant bit after the rest of the bits are shifted to the left
+ //data must be sent from the other microcontroller shifted out from the most significant bit to the least significant bit.
+ temp = (temp << 1) + serial_in;
+ j++;
+ data_flag = 0;
+ }
+ //when clock returns to low - reset data flag to accept the next bit.
+ if(!clock_pin && !data_flag)
+ data_flag = 1;
+ }
+
+ //clear lcd screen, print current build message
+ lcd.cls();
+ lcd.locate(0,3);
+ if(temp == ADDRESS)
+ {
+ rflag = 1;
+ lcd.printf("Address Received");
+ }
+ else if(temp == BROADCAST)
+ {
+ rflag = 1;
+ lcd.printf("Broadcast received");
+ }
+ else if(((temp & 0xF0) == NETWORK) && ((temp & 0x0F) == 0))
+ {
+ rflag = 1;
+ lcd.printf("Multicast received");
+ }//can add if Network==0 and address==x send to x in every network
+ else
+ printf("Wrong address received");
+
+ return rflag;
+}
+
+int read_byte(int size)
+{
+ j = 0;
+ temp = 0;
+
+ //read a byte/nibble at a time and return it to main
+ while(j<size)
+ {
+ //read in data if clock is 1 and data flag is 1
+ if(clock_pin && data_flag) {
+ //data is left shifted into our temporary variable.
+ //each new data bit is moved into the least significant bit afater the rest of the bits are shifted to the left
+ //data must be sent from the other microcontroller shifted out from the most significant bit to the least significant bit.
+ temp = (temp << 1) + serial_in;
+ //increment j (tracks bits received) - turn off data_flag until clock changes.
+ j++;
+ data_flag = 0;
+ }
+ //when clock returns to low - reset data flag to accept the next bit.
+ if(!clock_pin && !data_flag)
+ data_flag = 1;
+ }
+ return temp;
+}
+
+int check_crc(int temp_crc, unsigned char crc_calc)
+{
+ //assume data sent incorrectly, check crc to see if data sent correctly
+ int data_correct = 0;
+
+ //shift temp 3 bytes by 4 and add transmitted crc
+ temp_crc << 4;
+ temp_crc += crc_calc;
+ //check for crc correctness
+ if( (temp_crc % CRC) == 0)
+ data_correct = 1;
+
+ return data_correct;
+}
\ No newline at end of file
Kyle McKeehan
