[Kevin Watson]

I just wrote and tested some quick-n-dirty trig table code. Grab a copy of the EEPROM code here and add the code below. I only create a table covering zero to ninety degrees because sin(x) in the other three quadrants can be derived using sin(x) data in quadrant one (exercise left to the student). I'll release a more polished version at a later time.

This code creates the table:

 
#include <math.h>
#include "printf_lib.h"
#include "eeprom.h"
/*******************************************************************************
*
* FUNCTION: Sine_Table()
*
* PURPOSE: Creates a sine table in EEPROM
*
* CALLED FROM:
*
* PARAMETERS: Unsigned int containing the address.
*
* RETURNS: 1 when finished creating table, 0 otherwise
*
* COMMENTS:
*
*******************************************************************************/
unsigned char Sine_Table(unsigned int address)
{
static unsigned char angle = 0;
static unsigned char done_flag = 0;
static unsigned char sine;
if(EEPROM_Queue_Free_Space() > 0 && done_flag == 0)
{
// calculate normalized sine value
sine = (unsigned char)255.0 * sin((float)angle * 3.14159265 / 180.0);
// write the angle and sine value to EEPROM
EEPROM_Write(address + angle, sine);
// send diagnostic information to the terminal
printf("writing x=%u sin(x)=%u\r", (unsigned int)angle, (unsigned int)sine);
// are we done?
if(angle == 90)
{
done_flag = 1;
printf("Finished!\r\n");
}
else
{
angle++;
}
}
return(done_flag);
}

This code verifies that EEPROM was written correctly:

 
/*******************************************************************************
*
* FUNCTION: Verify_Sine_Table()
*
* PURPOSE: Creates a sine table in EEPROM
*
* CALLED FROM:
*
* PARAMETERS: Unsigned int containing the address.
*
* RETURNS: 1 when finished creating table, 0 otherwise
*
* COMMENTS:
*
*******************************************************************************/
unsigned char Verify_Sine_Table(unsigned int address)
{
static unsigned char angle = 0;
static unsigned char done_flag = 0;
if(done_flag == 0)
{
if(EEPROM_Read(address+angle) == (unsigned char)(255.0 * sin((float)angle * 3.14159265 / 180.0)))
{
printf("angle=%u verified\r", (unsigned int)angle);
}
else
{
printf("angle=%u failed\r\n", (unsigned int)angle);
}
if(angle == 90)
{
done_flag = 1;
printf("Finished!\r");
}
else
{
angle++;
}
}
return(done_flag);
}

This code goes into Process_Data_From_Master_uP():

if(Sine_Table(0) == 1)
{
Verify_Sine_Table(0);
}
EEPROM_Write_Handler();

-Kevin