[SOLVED] ATtiny402 ADC value comming not properly

ATtiny402 ADC value comming not properly

In ATtiny402 There is no increment ADC value when its came on +2.5v. Its stuck on that max adc value of when it reaches the corresponding +2.5v....there is no change even i adjust the trimpot above 2.5v. And here is code.

#include <avr/io.h> #include <util/delay.h> uint16_t volatile adcVal;

void ADC0_init(void); uint16_t ADC0_read(void);

void ADC0_init(void) { /* Disable digital input buffer */ PORTA.PIN6CTRL &= ~PORT_ISC_gm; PORTA.PIN6CTRL |= PORT_ISC_INPUT_DISABLE_gc;

  /* Disable pull-up resistor */
PORTA.PIN6CTRL &= ~PORT_PULLUPEN_bm;


ADC0.CTRLB = VREF_ADC0REFEN_bm ;
VREF.CTRLA = VREF_ADC0REFSEL_1_bm;  


ADC0.CTRLC |= ADC_PRESC_DIV4_gc      /* CLK_PER divided by 4 */
           | ADC_REFSEL_INTREF_gc;  /* Internal reference */


ADC0.CTRLA |= ADC_ENABLE_bm          /* ADC Enable: enabled */
           | ADC_RESSEL_10BIT_gc;   /* 10-bit mode */

/* Select ADC channel */
ADC0.MUXPOS  = ADC_MUXPOS_AIN6_gc;

}

uint16_t ADC0_read(void) { /* Start ADC conversion */ ADC0.COMMAND = ADC_STCONV_bm;

/* Wait until ADC conversion done */
while ( !(ADC0.INTFLAGS & ADC_RESRDY_bm) )
{
    ;
}

/* Clear the interrupt flag by writing 1: */
ADC0.INTFLAGS = ADC_RESRDY_bm;
return ADC0.RES;

}

Solution

This writes a mask with bit ADC0REFSEL_1 set and enables 2.5V reference voltage.

VREF.CTRLA = VREF_ADC0REFSEL_1_bm;

ADC can't measure voltages above the reference. Try different value or enable VDD as a reference on ADC0.CTRLC