adc_driver.c File Reference

XMEGA ADC driver source file. More...

#include "adc_driver.h"

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Functions
void	ADC_CalibrationValues_Set (ADC_t *adc)
	This function get the calibration data from the production calibration. More...
uint8_t	ADC_Offset_Get (ADC_t *adc)
	This function get the offset of the ADC. More...
uint8_t	ADC_ResultCh_GetHighByte (ADC_CH_t *adc_ch)
	This function clears the interrupt flag and returns the high byte of the coversion result. More...
uint8_t	ADC_ResultCh_GetLowByte (ADC_CH_t *adc_ch, uint8_t offset)
	This function clears the interrupt flag and returns the low byte of the coversion result. More...
uint16_t	ADC_ResultCh_GetWord (ADC_CH_t *adc_ch, uint8_t offset)
	This function clears the interrupt flag and returns the coversion result. More...
void	ADC_Wait_32MHz (ADC_t *adc)
	This function waits until the adc common mode is settled. More...
void	ADC_Wait_8MHz (ADC_t *adc)
	This function waits until the adc common mode is settled. More...

Detailed Description

XMEGA ADC driver source file.

This file contains the function implementations the XMEGA ADC driver.

The driver is not intended for size and/or speed critical code, since most functions are just a few lines of code, and the function call overhead would decrease code performance. The driver is intended for rapid prototyping and documentation purposes for getting started with the XMEGA ADC module.

For size and/or speed critical code, it is recommended to copy the function contents directly into your application instead of making a function call.

Several functions use the following construct: "some_register = ... | (some_parameter ? SOME_BIT_bm : 0) | ..." Although the use of the ternary operator ( if ? then : else ) is discouraged, in some occasions the operator makes it possible to write pretty clean and neat code. In this driver, the construct is used to set or not set a configuration bit based on a boolean input parameter, such as the "some_parameter" in the example above.

Application note:

AVR1300: Using the XMEGA ADC

Documentation

For comprehensive code documentation, supported compilers, compiler settings and supported devices see readme.html

Author

Atmel Corporation: http://www.atmel.com
Support email: avr@a.nosp@m.tmel.nosp@m..com

Revision

1714

Date

2008-08-13 11:09:37 +0200 (on, 13 aug 2008)

Copyright (c) 2008, Atmel Corporation All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
3. The name of ATMEL may not be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Definition in file adc_driver.c.

Function Documentation

ADC_CalibrationValues_Set()

void ADC_CalibrationValues_Set

(

ADC_t *

adc

)

This function get the calibration data from the production calibration.

The calibration data is loaded from flash and stored in the calibration register. The calibration data reduces the gain error in the adc.

Parameters

adc	Pointer to ADC module register section.

Definition at line 77 of file adc_driver.c.

References SP_ReadCalibrationByte().

Referenced by ADC_Init().

{
    if(&ADCA == adc){
         /* Get ADCCAL0 from byte address 0x20 (Word address 0x10. */
        adc->CAL = SP_ReadCalibrationByte(0x20);
    }else {
        /* Get ADCCAL0 from byte address 0x24 (Word address 0x12. */
        adc->CAL = SP_ReadCalibrationByte(0x24);
    }
}

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ADC_Offset_Get()

uint8_t ADC_Offset_Get

(

ADC_t *

adc

)

This function get the offset of the ADC.

This function make an internal coupling to the same pin and calculate the internal offset in the ADC.

Note

This function only return the low byte of the 12-bit convertion, because the offset should never be more than +-8 LSB off.

Parameters

adc	Pointer to the ADC to calculate offset from.

Returns

Offset on the selected ADC

Definition at line 241 of file adc_driver.c.

References ADC_Ch_Conversion_Complete, ADC_Ch_Conversion_Start, ADC_Ch_InputMode_and_Gain_Config, ADC_Ch_InputMux_Config, ADC_ConvMode_and_Resolution_Config, ADC_Disable, ADC_Enable, ADC_Prescaler_Config, ADC_Referance_Config, ADC_ResultCh_GetLowByte(), ADC_Wait_32MHz(), offset, and SP_ReadCalibrationByte().

Referenced by ADC_Init().

{
    uint8_t offset;

    /* Set up ADC to get offset. */
    ADC_ConvMode_and_Resolution_Config(adc, true, ADC_RESOLUTION_12BIT_gc);

    ADC_Prescaler_Config(adc , ADC_PRESCALER_DIV8_gc);

    ADC_Referance_Config(adc , ADC_REFSEL_INTVCC_gc);

    ADC_Ch_InputMode_and_Gain_Config(&(adc->CH0),
                                     ADC_CH_INPUTMODE_DIFF_gc,
                                     ADC_CH_GAIN_1X_gc);

    ADC_Ch_InputMux_Config(&(adc->CH0), ADC_CH_MUXPOS_PIN0_gc, ADC_CH_MUXNEG_PIN0_gc);

    /* Enable ADC. */
    ADC_Enable(adc);

    /* Wait until ADC is ready. */
    ADC_Wait_32MHz(adc);

    /* Do one conversion to find offset. */
    ADC_Ch_Conversion_Start(&(adc->CH0));

    do{
    }while(!ADC_Ch_Conversion_Complete(&(adc->CH0)));
    offset = ADC_ResultCh_GetLowByte(&(adc->CH0), 0x00);

    /* Disable ADC. */
    ADC_Disable(adc);

    return offset;
}

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ADC_ResultCh_GetHighByte()

uint8_t ADC_ResultCh_GetHighByte

(

ADC_CH_t *

adc_ch

)

This function clears the interrupt flag and returns the high byte of the coversion result.

This funtion should be used together with the ADC_ResultCh_ConversionComplete. When the conversion result is ready this funciton reads out the result.

Note

If this function is used with 12-bit right adjusted results, it returns the 8 LSB only. Offset is not compensated.

If ADC interrupts are enabled, the interrupt handler will clear the interrupt flag before the polling loop can detect it, and this function will hang forever. Therefore, do not use interrupts with this function. Instead, read the result registers directly.

Parameters

adc_ch

Pointer to ADC channel register section.

Returns

High byte of conversion result.

Definition at line 160 of file adc_driver.c.

{
    /* Clear interrupt flag.*/
    adc_ch->INTFLAGS = ADC_CH_CHIF_bm;

    /* Return low byte result register contents.*/
    return adc_ch->RESH;
}

ADC_ResultCh_GetLowByte()

uint8_t ADC_ResultCh_GetLowByte	(	ADC_CH_t *	adc_ch,
		uint8_t	offset
	)

This function clears the interrupt flag and returns the low byte of the coversion result.

This funtion should be used together with the ADC_Ch_Conversion_Complete. When the conversion result is ready this funciton reads out the result.

Note

If this function is used with 12-bit right adjusted results, it returns the 8 LSB only.

Parameters

adc_ch	Pointer to ADC channel register section.
offset	Compansation offset value.

Returns

Low byte of conversion result.

Definition at line 131 of file adc_driver.c.

References offset.

Referenced by ADC_Offset_Get().

{
    uint8_t answer;

    /* Clear interrupt flag.*/
    adc_ch->INTFLAGS = ADC_CH_CHIF_bm;
    /* Return result register contents*/
    answer = adc_ch->RESL - offset;

    return answer;
}

ADC_ResultCh_GetWord()

uint16_t ADC_ResultCh_GetWord	(	ADC_CH_t *	adc_ch,
		uint8_t	offset
	)

This function clears the interrupt flag and returns the coversion result.

This function should be used together with the ADC_Ch_Conversion_Complete. When the conversion result is ready this funciton reads out the result.

Parameters

adc_ch	Pointer to ADC channel register section.
offset	Offset value that is compansated for.

Returns

Conversion result.

Definition at line 98 of file adc_driver.c.

Referenced by mc_ADC_Scheduler().

{
    uint16_t answer;
    uint16_t signedOffset = (uint16_t) offset;

    /* Append 16-bit signed value if offset (signed) is negative. */
    if (offset >= 128){
        signedOffset |= 0xFF00;
    }

    /* Clear interrupt flag.*/
    adc_ch->INTFLAGS = ADC_CH_CHIF_bm;

    /* Return result register contents*/
    answer = adc_ch->RES - signedOffset;

    return answer;
}

ADC_Wait_32MHz()

void ADC_Wait_32MHz

(

ADC_t *

adc

)

This function waits until the adc common mode is settled.

After the ADC clock has been turned on, the common mode voltage in the ADC need some time to settle. The time it takes equals one dummy conversion. Instead of doing a dummy conversion this function waits until the common mode is settled.

Note

The function sets the prescaler to the minimum value possible when the clock speed is larger than 8 MHz to minimize the time it takes the common mode to settle.

The ADC clock is turned off every time the ADC i disabled or the device goes into sleep (not Idle sleep mode).

Parameters

adc	Pointer to ADC module register section.

Definition at line 214 of file adc_driver.c.

References COMMEN_MODE_CYCLES.

Referenced by ADC_Offset_Get().

{
    /* Store old prescaler value. */
    uint8_t prescaler_val = adc->PRESCALER;

    /* Set prescaler value to minimum value. */
    adc->PRESCALER = ADC_PRESCALER_DIV8_gc;

    /* wait 8*COMMEN_MODE_CYCLES for common mode to settle*/
    delay_us(8*COMMEN_MODE_CYCLES);

    /* Set prescaler to old value*/
    adc->PRESCALER = prescaler_val;
}

ADC_Wait_8MHz()

void ADC_Wait_8MHz

(

ADC_t *

adc

)

This function waits until the adc common mode is settled.

After the ADC clock has been turned on, the common mode voltage in the ADC need some time to settle. The time it takes equals one dummy conversion. Instead of doing a dummy conversion this function waits until the common mode is settled.

Note

The function sets the prescaler to the minimum value to minimize the time it takes the common mode to settle. If the clock speed is higher than 8 MHz use the ADC_wait_32MHz function.

Parameters

adc	Pointer to ADC module register section.

Definition at line 182 of file adc_driver.c.

References COMMEN_MODE_CYCLES.

Referenced by ADC_Init().

{
    /* Store old prescaler value. */
    uint8_t prescaler_val = adc->PRESCALER;

    /* Set prescaler value to minimum value. */
    adc->PRESCALER = ADC_PRESCALER_DIV4_gc;

    /* Wait 4*COMMEN_MODE_CYCLES for common mode to settle. */
    delay_us(4*COMMEN_MODE_CYCLES);

    /* Set prescaler to old value*/
    adc->PRESCALER = prescaler_val;
}