//If you  use win7 follow this to install Hyperterminal for  win7 , see
//http://h0w2.blogspot.hk/2011/09/how-to-enable-hyper-terminal-in-windows.html
//run  hypertrm.exe, set 57600	 (may be com4 depends on machine) for using adc
/********************************************************************/	
/*                                                                  */
/*                      Demo program for CUHK ARM board (2012)      */
/*                      ADC demo (2013)                             */										
/*                                                                  */										
/********************************************************************/
/*                                                                  */
/*                    ARM CPU: Philips NXP LPC2131                  */
/*                    Crystal clock: 11.0592 MHz                    */
/*                Serial port baudrate: 57600                       */
/*                Programming tool: KEIL uVision3 RealView for ARM  */			
/*                                                                  */
/********************************************************************/
#include <lpc21xx.h>

#define NEWLINE sendchar(0x0a); sendchar(0x0d)

//===============================
void  Init_Serial_A(void) {  
	U0LCR = 0x83;	//8 bit length ,DLAB=1	           
   	U0DLL = 0x0F;	//Pclk/(16*baudrate)=(11059200 x 5)/(4 x 16 x 57600);
   	U0DLM = 0x00;
   	U0LCR = 0x03;    //DLAB=0
}

char getchar(void) {
	volatile char ch = '0';

  	while ((U0LSR&&0x1)==0) // wait until  receive a byte
    ;
  	ch = U0RBR;         // receive character

  	return ch;
}

void sendchar(char ch) {
	while( (U0LSR&0x40)==0 );
    
 	U0THR  = ch;                     // Transmit next character
}

int  print(char *p) { 
	while(*p!='\0') {
      sendchar(*p++);
   }
   return(0);
}

void putint(int count) { 
	sendchar('0' + count/10000);
	sendchar('.');
	sendchar('0' + (count/1000) % 10);
	sendchar('0' + (count/100) % 10);
}

int read_sensor(int channel)
{
	int temp;
         
	ADCR=0x1<<channel;	//Set channel SEL field
	ADCR|=0x1200200;	//Start conversion now; ADC is operational;
						//11 clocks/ 10 bits; Software conversion mode;
						//CLKDIV = 2; ADclk = Pclk/(CLKDIV+1)
						//ADclk = (11059200 x 5)/(4 x 3) = 4.608MHz

	while(((temp=ADDR)&0x80000000)==0);	//check DONE flag
	temp>>=6;	//ADDR p6-p15 = RESULT
	temp&=0x3ff;//10 bits result

	return (temp*33);	//return 0-3V value precision is 1024 
}

int  main(void)
{

 PINSEL0 = 0x00000005;		// set p0.0 to TXD0, p0.1 to RXD0 and the rest to GPIO	
 PINSEL1 = 0x00400000;		// set p0.27 to ad0.0 and the rest to GPIO
 //PINSEL1 |= 0x01000000;		// set p0.28 to ad0.1
 //PINSEL1 |= 0x04000000;		// set p0.29 to ad0.2
 //PINSEL1 |= 0x10000000;		// set p0.30 to ad0.3
 //PINSEL1 |= 0x00040000;		// set p0.25 to ad0.4

 
 Init_Serial_A();		// Init COM port
 
 NEWLINE;
 print("======================================================================="); NEWLINE;
 print("*                                                                     *"); NEWLINE;
 print("*         CUHK Computer Science and Engineering Department            *"); NEWLINE;
 print("*                  LPC2131 ARM Board (2012)                           *"); NEWLINE;
 print("*                  ADC demo (2013)                                    *"); NEWLINE;
 print("*                                                                     *"); NEWLINE;
 print("======================================================================="); NEWLINE;
 NEWLINE;

 while(1) {
 	print("Sensor value = ");
 	putint(read_sensor(0));
	print(" volts");
 	NEWLINE;
 	NEWLINE;
 	}
 }