program electronique_pic_tuto_base_i2c_pcf8591_001a;

const
  cPCF8591_W = $90;
  cPCF8591_R = $91;

var
  Values: array[0..3] of byte;
  i, iConf, iVal: byte;
  LCD_RS : sbit at LATA4_bit;
  LCD_EN : sbit at LATA5_bit;
  LCD_D4 : sbit at LATA0_bit;
  LCD_D5 : sbit at LATA1_bit;
  LCD_D6 : sbit at LATA2_bit;
  LCD_D7 : sbit at LATA3_bit;
  LCD_RS_Direction : sbit at TRISA4_bit;
  LCD_EN_Direction : sbit at TRISA5_bit;
  LCD_D4_Direction : sbit at TRISA0_bit;
  LCD_D5_Direction : sbit at TRISA1_bit;
  LCD_D6_Direction : sbit at TRISA2_bit;
  LCD_D7_Direction : sbit at TRISA3_bit;

procedure Main_Init;
begin
  CMCON := $07;             // turn off comparators
  INTCON2.NOT_RBPU := 0;    // activate pullup
  ADCON1 := ADCON1 or $0F;  // turn off analog inputs
  TRISA := $00;             // outputs
  TRISB := $FF;             // inputs
  PORTA := $00;
  PORTB := $00;
  // I2C comm init
  I2C1_Init(100000);
  // LCD init
  Lcd_Init;                
  Lcd_Cmd(_LCD_CURSOR_OFF);
end;

procedure Display_Refresh;
var
  sVal, sIdx: string[3];
  s: string[20];
begin
  Lcd_Cmd(_LCD_CLEAR);
  for i := 0 to 3 do
  begin
    ByteToStr(Values[i], sVal);
    ByteToStr(i, sIdx);
    s := sIdx + ' : ' + sVal;
    LCD_Out(i + 1, 1, s);
  end;
end;

procedure PCF8591_Write;
begin
  // config CAN
  iConfig := $40;
  iVal := PORTB;
  I2C1_Start;           // signal START
  I2C1_Wr(cPCF8591_W);  // Addresse PCF8591
  I2C1_Wr(iConf);       // envoi configuration générale
  I2C1_Wr(iVal);        // envoi valeur sortie analogique
  I2C1_Stop;            // signal STOP
end;

procedure PCF8591_Read_All;
begin
  // config CAN
  iConf := $44;
  I2C1_Start;             // signal START
  I2C1_Wr(cPCF8591_W);    // addresse PCF8591
  I2C1_Wr(iConf);         // envoi configuration générale
  I2C1_Stop;              // signal STOP
  // read analog Values
  I2C1_Start;              // signal START
  I2C1_Wr(cPCF8591_R);     // addresse PCF8591
  Values[0] := I2C1_Rd(1); // lecture entree analogique "prev"
  Values[0] := I2C1_Rd(1); // lecture entree analogique #0
  Values[1] := I2C1_Rd(1); // lecture entree analogique #1
  Values[2] := I2C1_Rd(1); // lecture entree analogique #2
  Values[3] := I2C1_Rd(0); // lecture entree analogique #3
  I2C1_Stop;               // signal STOP
end;

procedure PCF8591_Read_One(idx: byte);
begin
  // config CAN
  iConf := $40;
  iConf := iConf xor idx; //
  I2C1_Start;             // signal START
  I2C1_Wr(cPCF8591_W);    // addresse PCF8591
  I2C1_Wr(iConf);         // envoi configuration générale
  I2C1_Stop;              // signal STOP
  // read analog value
  I2C1_Start;             // signal START
  I2C1_Wr(cPCF8591_R);    // addresse PCF8591
  iVal := I2C1_Rd(1);     // lecture entree analogique
  iVal := I2C1_Rd(0);     // lecture entree analogique
  I2C1_Stop;              // signal STOP
  Values[idx] := iVal;
end;

procedure PCF8591_Read;
begin
  // sample values on analog inputs
  if 1 = 1 then
  begin
    PCF8591_Read_All;
  end
  else
  begin
    PCF8591_Read_One(0);
    PCF8591_Read_One(1);
    PCF8591_Read_One(2);
    PCF8591_Read_One(3);
  end;
  // show sampled Values on LCD display
  Display_Refresh;
end;

begin
  Main_Init;
  delay_ms(500);
  while true do
  begin
    // read PCF8591 analog inputs
    PCF8591_Read;
    Delay_ms(250);
    //write to PCF8591 analog output
    PCF8591_Write;
    Delay_ms(250);
  end;
end.

const
 cPCF8591_W = $90;
 cPCF8591_R = $91;