//Displaying Temperature sensor (ATD chan1) of Axiom Peripheral (TWR-DEV-PERIPH) board on LEDs of PORTT for HCS12G128 Tower Board 
//Modified and tested by Mazidi from Program 13-1C of HCS12 book by Mazidi & Causey 
//Notice the on-chip ADC of HCS12G is slightly different from the HCS12DT256/512 covered in the textbook
//See Chapters 12/13 (ADC10B12CV2) in the MC9S12GRMV1.pdf ref. Manual
//In TWR-S12G128 the Bus Freq=6.25 MHz. 
//On the Axiom TWR-DEV-PERIPH board, the ATD channel 1 (AN1) is connected to MCP9700 Temperature sensor
//This program displays the room temperature in Celsius (in binary)

//The MPC9700 Temperature sensor is U1 on TWR-DEV-PERIPH board
//and it is located on the right side of the letter A of keypad 
//The Voltage for Vref on TWR-HCS12G128 module is connected to Vdd(5V). That means the step size is 20 mV
//Therefore the temp value you get is twice of what should be since MPC9700 gives us 10mV per degree Celsius.
//Touch the TempSensor or blow hot air (with your mouth) on it to see the LEDs change
  
//On the Axiom TWR-DEV-PERIPH board make sure you have jumpers: JP1 set on the left, JP2 is set, and JP3,JP4, and JP5 on the right. 
//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) 
{
	unsigned char MyTemp;
        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 = 1;		// start a single conversion on channel 1
				
		while(!(ATDSTAT0 & 0x80));
		//while(ATDSTAT0_SCF==0x80);  //you can also use this instead  
		MyTemp = ATDDR0L;   //Notice the conversion result is in low bye of ATDDR0 register (ATDDR0L) 
		MyTemp = MyTemp<<4; //shift it left 4 times since you are displaying upper LED4-LED1
                PTT = ~MyTemp;    // dump it on LEDs (invert the value because LEDs are low active)
        			   //you can also connect 4 more LEDs to PT3-PT0 on a breadboard and see all 8 bits. 	
                MSDelay(50);     //optional
	}
}

void MSDelay(unsigned int itime)
{
	unsigned int i; unsigned int j;
	for(i=0;i<itime;i++)
		for(j=0;j<1000;j++);
}