ADC Library

ADC (Analog to Digital Converter) module is available with a number of AVR MCUs. Several library routines are included to provide you comfortable work with the module in single-ended mode.

Library Routines

ADC_Init
ADCx_Init_Advanced
ADC_Get_Sample
ADC_Read

ADC_Init

Prototype	sub procedure ADC_Init() ' for XMEGA family of MCUs sub procedure ADCx_Init()
Returns	Nothing.
Description	Initializes internal ADC module to work with XTAL frequency prescaled by 128. Clock determines the time period necessary for performing A/D conversion. For XMEGA family of MCUs change the X in the routine prototype with A or B.
Requires	MCU with built-in ADC module.
Example	ADC_Init() ' Initialize ADC module with default settings ADCA_Init() ' Initialize ADC module with default settings

ADCx_Init_Advanced

Prototype

sub procedure ADCx_Init_Advanced(dim AdcMode, Reference as byte)

Returns

Nothing.

Description

Initializes internal ADC module to work with user defined settings.
Exist only for XMEGA family of MCUs
In order to use this routine, change the X in the routine prototype with A or B.

Parameters AdcMode and Reference determine the work mode for ADC module and can have the following values:

Description	Predefined library const
Resolution of ADC module :
`8 bit resolution`	`_ADC_8bit`
`12 bit resolution`	`_ADC_12bit`
Voltage Reference :
`Internal 1V`	`_ADC_INTERNAL_REF_1V`
`Internal VCC/1.6V`	`_ADC_INTERNAL_REF_VCC`
`External Reference on PORTA`	`_ADC_EXTERNAL_REF_A`
`External Reference on PORTB`	`_ADC_EXTERNAL_REF_B`

Requires

MCU with built-in ADC module.

Example

ADCA_Init_Advanced(_ADC_12bit, _ADC_INTERNAL_REF_1V)  ' Initialize ADC module with 12bit resolution and internal voltage reference of 1V

ADC_Get_Sample

Prototype	sub function ADC_Get_Sample(dim channel as byte) as word ' for XMEGA family of MCUs sub function ADCx_Get_Sample(dim channel as byte) as word
Returns	10-bit or 12-bit unsigned value (MCU dependent) from the specified `channel`.
Description	Routine acquires analog value from the specified channel. Parameter `channel` represents the channel from which the analog value is to be acquired. Refer to the appropriate datasheet for channel-to-pin mapping. For XMEGA family of MCUs change the X in the routine prototype with A or B.
Requires	The MCU with built-in ADC module. Prior to using this routine, ADC module needs to be initialized. See ADC_Init.
Example	dim adc_value as word ... ADC_Init() ' Initialize ADC module with default settings adc_value = ADC_Get_Sample(2) ' Acquire analog value from channel 2

ADC_Read

Prototype	sub function ADC_Read(dim channel as byte) as word ' for XMEGA family of MCUs sub function ADC_Read(dim channel as byte) as word
Returns	10-bit or 12-bit unsigned value (MCU dependent) from the specified `channel`.
Description	Routine initializes internal ADC module and acquires analog value from the specified `channel`. Clock determines the time period necessary for performing A/D conversion. Parameter `channel` represents the channel from which the analog value is to be acquired. Refer to the appropriate datasheet for channel-to-pin mapping. For XMEGA family of MCUs change the X in the routine prototype with A or B.
Requires	Nothing.
Example	dim adc_value as word ... adc_value = ADC_Read(2) ' initialize ADC module and acquire analog value from ADC module channel 2

Library Example

This example code reads analog value from channel 2 and displays it on PORTB and PORTC.

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program ADC_on_LEDs

dim adc_rd as word

main:
  DDRB = 0xFF               ' set PORTB as output
  DDRC = 0xFF               ' set PORTC as output
  
  while TRUE
    adc_rd = ADC_Read(2)    ' get ADC value from 2nd channel
    PORTB = adc_rd          ' display adc_rd[7..0]
    PORTC = Hi(adc_rd)      ' display adc_rd[9..8]
  wend
end.

HW Connection

ADC HW connection

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