#include "biosdem.h"
#include <pic.h>
void waitRAT(void);
/* Turn on ADC */
void adc_on(void)
	{
	 ADCON1 = 0x0E ; /* RA0 analogique seulement */
	 ADCON0 = 0x41 ; /*Tad = 8*Tosc = 8 * 0.25µs = 2µs > 1.6µs , ADON ;*/
	 ADIF = 0 ;
	}

/* Start convert channel ch */
/*and read 8 most significant bits when complete */
unsigned char adc_read_8b(unsigned char ch)	
	{
	  
	  ADCON0 &= 0xC7 ;  /* RAZ CHSx */
			    /* Sélection du canal */
	  if ( ch & 1 )
            {
             CHS0  = 1 ;
	    }
	  if ( ch & 2 )
            {
             CHS1  = 1 ;
	    }
	  if ( ch & 4 )
            {
             CHS2  = 1 ;
	    }

	  waitRAT();            /* Attendre le temps d'acquisition */
	
    	  ADGO = 1 ;            /* Démarre la conversion */
				/* Attend la fin de conversion */
	  while (ADGO && ADON)  /* Par sécurité on teste aussi ADON */
		;		/* car sinon on rentre dans une boucle infinie */
	  return ADRESH ;
	}

/********************************************************************************************
 * Required acquisition time for A/D module form Max. Heise 2002	
 * p. 115 equation 11-1 Tacq=19,72,e-6
 * seconds, approx. 2,e-5 seconds.
 * One instruction is executed in one
 * cycle, one cycle at 4MHz takes 2,5,e-7
 * seconds. Thus we must idle for 80
 * instructions
 * Formula for this loop
 * Inst(I)=1+1+( (I-1)*(1+2) )+2+2=6+3I-3=3I+3 
 * +2 Inst.Cycles for the call of this function
 * => Inst(I)=3I+5 
 * Inst(I) must be 80
 * 80=3I+5
 * => I=25
 * Timing critical, so this is still in assembler.
 ********************************************************************************************/
char counter ;
void waitRAT(void) {

#asm
  I EQU 50      ; Note this is actually twice the required value of I, just to be sure
  movlw  I	; 1 Inst.Cycle
  movwf  _counter    ; 1 Inst.Cycle
WaitRAT_Loop
  decfsz _counter,f  ; 1 Inst.Cycle if I!=0, 2 Inst.Cycles if I==0
  goto   WaitRAT_Loop ; 2 Inst.Cycles
#endasm
}