//Displaying ATD channel 0 (POT) on LEDs of PORTT for HCS12G128 Tower Board 
//Modified and tested by Mazidi from Program 13-1C of HCS12 book by Mazidi & Causey 
//With Contribution from Shu-Jen Chen
//Notice the on-chip ADC of HCS12G is slightly different from the HCS12DT256/512 covered in the textbook
//See Chapter 12 (ADC10B12CV2) in the MC9S12GRMV1.pdf ref. Manual
//In TWR-S12G128 the Bus Freq=6.25 MHz. 
//ATD channel 0 (AN0) is connected to RV1 brown Pot Trimer
//Change the POT to see the changes on LEDs of PORTT

//In Codewarrior, make sure you are in Open Source BDM
//In Codewarrior F7(make), F5(Debug) and F5 again to start running
 
#include <hidef.h>      /* common defines and macros */
#include "derivative.h"      /* derivative-specific definitions */


void MSDelay(unsigned int);
void main(void) 
{
	DDRT = 0xF0;		// PORTT as output

	ATDCTL1 = 0;		// 8-bit resolution
	ATDCTL3 = 0x88;		// right justified, one sample per sequence
	ATDCTL4 = 0x02;		// prescaler = 2; ATD clock = 6.25MHz / (2 * (2 + 1)) == 1.04MHz
				// should be between 0.25MHz and 8 MHz per specs.
	for(;;)
	{
		ATDCTL5 = 0;		// start a single conversion on channel 0
				
		while(!(ATDSTAT0 & 0x80));
		  
		PTT = ~ATDDR0L;  // dump it on LEDs (invert the value because LEDs are low active)

		//MSDelay(250);     //optional
	}
}

void MSDelay(unsigned int itime)
{
	unsigned int i; unsigned int j;
	for(i=0;i<itime;i++)
		for(j=0;j<40;j++);
}