ADC Library

ADC (Analog to Digital Converter) module is available with a number of AVR MCU modules. ADC is an electronic circuit that converts continuous signals to discrete digital numbers. ADC Library provides you a comfortable work with the module.

Library Routines

ADC_Init
ADCx_Init_Advanced
ADC_Get_Sample
ADC_Read
ADC_Set_Active

ADC_Init

Prototype	procedure ADC_Init(); // for XMEGA family of MCUs 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

procedure ADCx_Init_Advanced(AdcMode, Reference : 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	function ADC_Get_Sample(channel : byte) : word; // for XMEGA family of MCUs function ADCx_Get_Sample(channel : byte) : 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	var adc_value : word ... ADC_Init(); // Initialize ADC module with default settings adc_value := ADC_Get_Sample(2); // Acquire analog value from channel 2

ADC_Read

Prototype	function ADC_Read(channel : byte) : word; // for XMEGA family of MCUs function ADCx_Read(channel : byte) : 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	var tmp : word; ... tmp := ADC_Read(2); // initialize ADC module and acquire analog value from ADC module channel 2

ADC_Set_Active

Prototype	procedure ADC_Set_Active(adc_gs : ^TADC_Get_Sample);
Description	Sets active ADC module.
Parameters	Parameters : `adc_gs:` ADC_Get_Sample handler.
Returns	Nothing.
Requires	Routine is available only for MCUs with multiple ADC modules. Used ADC module must be initialized before using this routine. See ADC_Init and ADCx_Init_Advanced routines.
Example	// Activate ADC2 module ADC_Set_Active(@ADC2_Get_Sample);
Notes	None.

Library Example

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

Copy Code To Clipboard

program ADC_on_LEDs;

var adc_rd : word;

begin

  DDRB := 0xFF;               // Set PORTB as output
  DDRC := 0xFF;               // Set PORTC as output
  
  while (TRUE) do
    begin
      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]
    end;
end.

HW Connection

ADC HW connection

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