Estoy trabajando en un proyecto escolar donde necesito leer un grupo de valores analógicos y convertirlos a digital con PIC16F1788 ( hoja de datos ). Escribí la función usando el compilador C y xc8. El problema es que cuando lo pruebo no se comporta como debería. Cuando quito el potenciómetro, el LED permanece encendido aunque todo debería estar apagado ya que ya no hay entrada analógica. Aquí está mi código, gracias por su ayuda.
#include <pic16f1788.h>
#include <stdio.h>
#include <stdlib.h>
#include <xc.h>
// Config word
#define _XTAL_FREQ 32000000
/*config1 and config2 settings*/
void InitADC(void)
{
// CONFIG1
#pragma config FOSC = INTOSC // Oscillator Selection (INTOSC oscillator: I/O f unction on CLKIN pin)
#pragma config WDTE = ON // Watchdog Timer Enable (WDT enabled)
#pragma config PWRTE = OFF // Power-up Timer Enable (PWRT disabled)
#pragma config MCLRE = ON // MCLR Pin Function Select (MCLR/VPP pin function is MCLR)
#pragma config CP = OFF // Flash Program Memory Code Protection (Program memory code protection is disabled)
#pragma config CPD = OFF // Data Memory Code Protection (Data memory code protection is disabled)
#pragma config BOREN = ON // Brown-out Reset Enable (Brown-out Reset enabled)
#pragma config CLKOUTEN = OFF // Clock Out Enable (CLKOUT function is disabled. I/O or oscillator function on the CLKOUT pin)
#pragma config IESO = ON // Internal/External Switchover (Internal/External Switchover mode is enabled)
#pragma config FCMEN = ON // Fail-Safe Clock Monitor Enable (Fail-Safe Clock Monitor is enabled)
// CONFIG2
#pragma config WRT = OFF // Flash Memory Self-Write Protection (Write protection off)
#pragma config VCAPEN = OFF // Voltage Regulator Capacitor Enable bit (Vcap functionality is disabled on RA6.)
#pragma config PLLEN = ON // PLL Enable (4x PLL enabled)
#pragma config STVREN = ON // Stack Overflow/Underflow Reset Enable (Stack Overflow or Underflow will cause a Reset)
#pragma config BORV = LO // Brown-out Reset Voltage Selection (Brown-out Reset Voltage (Vbor), low trip point selected.)
#pragma config LPBOR = OFF // Low Power Brown-Out Reset Enable Bit (Low power brown-out is disabled)
#pragma config LVP = ON // Low-Voltage Programming Enable (Low-voltage programming enabled)
//** Initalise Ports FOR ADC **//
PORTA = 0x00; //Set ports to low
PORTB = 0x00;
TRISA = 0xFF; //Port A is all inputs. (set to 1)
//** Set Up ADC Parameters **//
ANSELA =0x2F ; // (0b00101111)All AN0-AN4(RA4 and RA7 have no ADC) of register A are set to analog input
//ANSELH = 0x00; //Set the analog high bits to 0
ADCON1 = 0x00; // Sets ADRESL to contain the first 7 bits of conversion, ADRESH will have the final 3 bits. And all the rest to default (FOSC/2 2 prescaler)
} // void InitADC(void)
// Do the ADC convertion only for the channel indicated
// result of ADC is returned
unsigned int ReadADC(unsigned char channel)
{
unsigned int AN_Val;
// automaticaly determines the input channel it will read the value from
switch (channel)
{
case 1: // AN1 1000 0101
ADCON0 = 0x85;
break;
case 2: // AN2 1000 1001
ADCON0 = 0x89;
break;
case 3: //AN3 1000 1101
ADCON0 = 0x8D;
break;
case 4: //AN4 1001 0001
ADCON0 = 0x91;
break;
default: // Any other value will default to AN0
ADCON0 = 0x81; // (1000 0001) - AN1 set up ADC ADCON0
// sets the ADCON0 register for each port depending on the value of channel.
// the result is 10-bit , The ADC is set to on, No convertion is in progress
} // switch (channel)
// Channel selected proceed with ADC convertion
__delay_us(10); // sampling time
ADCON0 = ADCON0 | 0x02; //This sets the go/!done bit that starts conversion. Bit will be cleared when ADC is complete
while (ADCON0 & 0x02); //wait here until conversion is complete
AN_Val = ((ADRESH << 8) + ADRESL) & 0x03ff; //result is 16 bits with 10-bits for measurement. Shift upper 8 bits left 8 bits into high byte and add low byte.
return AN_Val;
} // int ADC(unsigned char channel)
void main (void){
//** Initalise Ports FOR ADC **//
unsigned int AN1_Result;
unsigned int AN0_Result;
unsigned int AN2_Result;
PORTC = 0x00;
TRISC = 0x00; //Port C all output
// TRISB = 0x00;
// in the following function I am trying to test and see if the code works by using a POT and changing the value and see if LEDs in port C would react to that.
do{
AN0_Result = ReadADC(0);
PORTC = AN0_Result;
}while(1);
}
Actualización # 1:
basado en algunas de las sugerencias, actualicé mi código de la siguiente manera:
Los problemas que sigo teniendo son que, incluso cuando no hay una entrada analógica, el led conectado a PORTC permanece encendido. Incluso cuando conecto a tierra la entrada usando una resistencia a tierra. Eso solo me dice que hay algo mal con mi función ReadADC. Volví a revisar mi código y sospecho que hay algo mal en las siguientes líneas que aún no entiendo:
ADCON0 = ADCON0 | 0x02; //This sets the go/!done bit that starts conversion. Bit will be cleared when ADC is complete
while (ADCON0 & 0x02); //wait here until conversion is complete
AN_Val = ((ADRESH << 6) + ADRESL)& 0x03ff ; // shift the ADRESh register by 6 bits to get rid of extra 0's and then add the bottom 8bits to it which gives the whole 10bit answer. (somebody suggested to & with 0x03ff still dont know why this could be wrong)
además de que cambié el código como algunos de ustedes notaron y movieron adc init dentro de la función ReadADC y agregué un par de líneas que tenían sentido para mí, aquí está
#include <xc.h>
// Config word
#define _XTAL_FREQ 500000 // set it to match internal oscillator
#DEVICE ADC=10 // set ADC to 10 bit resolution
/*config1 and config2 settings*/
// CONFIG1
#pragma config FOSC = INTOSC // Oscillator Selection (INTOSC oscillator: I/O f unction on CLKIN pin)
#pragma config WDTE = OFF // Watchdog Timer Enable (WDT enabled)
#pragma config PWRTE = OFF // Power-up Timer Enable (PWRT disabled)
#pragma config MCLRE = ON // MCLR Pin Function Select (MCLR/VPP pin function is MCLR)
#pragma config CP = OFF // Flash Program Memory Code Protection (Program memory code protection is disabled)
#pragma config CPD = OFF // Data Memory Code Protection (Data memory code protection is disabled)
#pragma config BOREN = ON // Brown-out Reset Enable (Brown-out Reset enabled)
#pragma config CLKOUTEN = OFF // Clock Out Enable (CLKOUT function is disabled. I/O or oscillator function on the CLKOUT pin)
#pragma config IESO = ON // Internal/External Switchover (Internal/External Switchover mode is enabled)
#pragma config FCMEN = ON // Fail-Safe Clock Monitor Enable (Fail-Safe Clock Monitor is enabled)
// CONFIG2
#pragma config WRT = OFF // Flash Memory Self-Write Protection (Write protection off)
#pragma config VCAPEN = OFF // Voltage Regulator Capacitor Enable bit (Vcap functionality is disabled on RA6.)
#pragma config PLLEN = ON // PLL Enable (4x PLL enabled)
#pragma config STVREN = ON // Stack Overflow/Underflow Reset Enable (Stack Overflow or Underflow will cause a Reset)
#pragma config BORV = LO // Brown-out Reset Voltage Selection (Brown-out Reset Voltage (Vbor), low trip point selected.)
#pragma config LPBOR = OFF // Low Power Brown-Out Reset Enable Bit (Low power brown-out is disabled)
#pragma config LVP = ON // Low-Voltage Programming Enable (Low-voltage programming enabled)
// Do the ADC convertion only for the channel indicated
// result of ADC is returned
unsigned int ReadADC(unsigned char channel)
{
unsigned int AN_Val;
unsigned int bit_val;
//** Initalise Ports FOR ADC **//
PORTA = 0x00; //Set ports to low
PORTB = 0x00;
TRISA = 0xFF; //Port A is all inputs. (set to 1)
//** Set Up ADC Parameters **//
ANSELA =0x2F ; // (0b00101111)All AN0-AN4(RA4 and RA7 have no ADC) of register A are set to analog input
ADCON1 = 0x00; // Sets ADRESL to contain the first 7 bits of conversion, ADRESH will have the final 3 bits. And all the rest to default (FOSC/2 2 prescaler)
// automaticaly determines the input channel it will read the value from
switch (channel)
{
case 1: // AN1 1000 0101
ADCON0 = 0x85;
break;
case 2: // AN2 1000 1001
ADCON0 = 0x89;
break;
case 3: //AN3 1000 1101
ADCON0 = 0x8D;
break;
case 4: //AN4 1001 0001
ADCON0 = 0x91;
break;
default: // Any other value will default to AN0
ADCON0 = 0x81; // (1000 0001) - AN1 set up ADC ADCON0
// sets the ADCON0 register for each port depending on the value of channel.
// the result is 10-bit , The ADC is set to on, No convertion is in progress
} // switch (channel)
// Channel selected proceed with ADC convertion
__delay_us(10); // sampling time
ADCON0 = ADCON0 | 0x02; //This sets the go/!done bit that starts conversion. Bit will be cleared when ADC is complete
while (ADCON0 & 0x02); //wait here until conversion is complete
bit_val= ADRESH
AN_Val = ((bit_val << 8) | ADRESL); //store the ADRESH into the 16 bit int then shit it up 8 spaces after that add the ADRESL values using the and operator.
return AN_Val;
} // int ADC(unsigned char channel)
void main (void){
//** Initalise Ports FOR ADC **//
unsigned int AN1_Result;
unsigned int AN0_Result;
unsigned int AN2_Result;
PORTC = 0x00;
TRISC = 0x00; //Port C all output
// in the following function I am trying to test and see if the code works by using a POT and changing the value and see if LEDs in port C would react to that.
do{
AN0_Result = ReadADC(0);
LATC = AN0_Result;
}while(1);
}
ACTUALIZACIÓN # 2
Ahora el ADC funciona, pero la salida no es del todo correcta. Lo probé utilizando 3 LEDs. Dos leds se encenderían cuando el voltaje esté por encima de los 2,5 voltios y un solo LED se iluminaría si está por debajo de 2.5v. El problema es que ocurre lo contrario. Dos leds se encenderían si el voltaje está por debajo y uno solo se iluminaría si el voltaje es superior a 2.5V. También revisé mi circuito y todo parece correcto.
#include <xc.h>
// Config word
#define _XTAL_FREQ 2000000 // set it to match internal oscillator
// Do the ADC convertion only for the channel indicated
// result of ADC is returned
unsigned int ReadADC(unsigned char channel)
{
unsigned int AN_Val;
unsigned int bit_val;
//** Initalise Ports FOR ADC **************************************************************//
PORTA = 0x00; //Set ports to low
PORTB = 0x00;
TRISA = 0xFF; //Port A is all inputs. (set to 1)
//** Set Up ADC Parameters **//
ANSELA =0x2F ; // (0b00101111)All AN0-AN4(RA4 and RA7 have no ADC) of register A are set to analog input
ADCON1 = 0xD0; // (0b11010000)
//format setup see page 182 of datasheet
// bit7: set for 2'complement format
// bit6-4 : set FOSC/16
//********************************************************************************************//
// automaticaly determines the input channel it will read the value from
switch (channel)
{
case 1: // AN1 1000 0101
ADCON0 = 0x85; // bit0: ADC enabled
//bit6-2: AN1 enabled for analog input
//bit7: set for a 10-bit result(when its 1)
break;
case 2: // AN2 1000 1001
ADCON0 = 0x89;
break;
case 3: //AN3 1000 1101
ADCON0 = 0x8D;
break;
case 4: //AN4 1001 0001
ADCON0 = 0x91;
break;
default: // Any other value will default to AN0
ADCON0 = 0x81; // (1000 0001) - AN1 set up ADC ADCON0
// sets the ADCON0 register for each port depending on the value of channel.
// the result is 10-bit , The ADC is set to on, No convertion is in progress
} // switch (channel)
// Channel selected proceed with ADC convertion
__delay_us(10); // sampling time
ADCON0 = ADCON0 | 0x02; //This sets the go/!done bit that starts conversion. Bit will be cleared when ADC is complete
while (ADCON0 & 0x02); //wait here until conversion is complete
bit_val= ADRESH; // store upper 2 bits in a 16 bit int
AN_Val = ((bit_val << 8) | ADRESL); //store the ADRESH into the 16 bit int then shit it up 8 spaces after that add the ADRESL values using the and operator.
return AN_Val;
} // int ADC(unsigned char channel)
void main (void){
//** Initalise Ports FOR ADC **//
unsigned int AN1_Result;
unsigned int AN0_Result;
unsigned int AN2_Result;
PORTC = 0x00;
TRISC = 0x00; //Port B all output
//TRISB = 0x00;
//ANSELB = 0x00; // all as port b digital as in/out
ANSELC = 0x00;
while(1){
AN0_Result = ReadADC(1);
if(AN0_Result > 512){ // when the voltage is passed 2.5 volts these two LEDS should come on.
/*Turn these 2 LED on*/
LATCbits.LATC2 = 1;
LATCbits.LATC3 = 1;
LATCbits.LATC4 = 0;
}
if (AN0_Result < 512){
/*turn one LED on*/
LATCbits.LATC2 = 0;
LATCbits.LATC3 = 0;
LATCbits.LATC4 = 1;
}
}
}