ADC Library
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ADC Library

ADC (Analog to Digital Converter) module is available with a number of dsPIC30/33 and PIC24 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

ADCx_Init

Prototype

void ADCx_Init();
Description

This routines configures ADC module to work with default settings.

The internal ADC module is set to:

  • single channel conversion
  • 10-bit conversion resolution
  • unsigned integer data format
  • auto-convert
  • VRef+ : AVdd, VRef- : AVss
  • instruction cycle clock
  • conversion clock : 32*Tcy
  • auto-sample time : 31TAD
Parameters

None.
Returns

Nothing.
Requires
  • MCU with built-in ADC module.
  • ADC library routines require you to specify the module you want to use. To select the desired ADC module, simply change the letter x in the routine prototype for a number from 1 to 2.
Example 
ADC1_Init();  // Initialize ADC1 module with default settings
Notes
  • Number of ADC modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

ADCx_Init_Advanced

Prototype // dsPIC30F and PIC24FJ prototype

void ADC1_Init_Advanced(unsigned Reference);

// dsPIC33FJ and PIC24HJ prototype

void ADCx_Init_Advanced(unsigned ADCMode, unsigned Reference);

// dsPIC33EVXXXGM00X_10X

void ADCx_Init_Advanced(unsigned ADCMode, unsigned channel);
Description

This routine configures the internal ADC module to work with user defined settings.
Parameters
  • ADCMode: resolution of the ADC module.
  • Reference: voltage reference used in ADC process.
  • channel represents the channel from which the analog value is to be acquired (only for dsPIC33EVXXXGM00X_10X).
    Description Predefined library const
    ADC mode:
    10-bit resolution _ADC_10bit
    12-bit resolution _ADC_12bit
    Voltage reference:
    Internal voltage reference (from AVdd and AVss) _ADC_INTERNAL_REF
    External voltage reference (from VREF+ and VREF- Pins) _ADC_EXTERNAL_VREF
    Internal Positive Voltage Reference from AVdd _ADC_INTERNAL_VREFH
    Internal Negative Voltage Reference from AVss _ADC_INTERNAL_VREFL
    External Positive Voltage Reference from VREF+ Pin _ADC_EXTERNAL_VREFH
    External Negative Voltage Reference from VREF- Pin _ADC_EXTERNAL_VREFL
    Internal Positive Voltage Reference VRH1 (2 * Internal VBG) _ADC_INTERNAL_VRH1
    Internal Positive Voltage Reference VRH2 (4 * Internal VBG) _ADC_INTERNAL_VRH2
Returns

Nothing.
Requires
  • The MCU with built-in ADC module.
  • ADC library routines require you to specify the module you want to use. To select the desired ADC module, simply change the letter x in the routine prototype for a number from 1 to 2.
Example 
ADC1_Init_Advanced(_ADC_10bit, _ADC_INTERNAL_REF);  // sets ADC module in 10-bit resolution mode with internal reference used
ADC1_Init_Advanced(_ADC_12bit, _ADC_INTERNAL_VREFL | _ADC_INTERNAL_VREFH);  // sets ADC module in 12-bit resolution mode with the following reference : AVss and VREF+
Notes
  • Number of ADC modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.
  • Not all MCUs support advanced configuration. Please, read the appropriate datasheet before utilizing this library.

ADCx_Get_Sample

Prototype

unsigned ADCx_Get_Sample(unsigned channel);
Description

The function enables ADC module and reads the specified analog channel input.
Parameters
  • channel represents the channel from which the analog value is to be acquired.
Returns

10-bit or 12-bit (depending on selected mode by ADCx_Init_Advanced or MCU) unsigned value from the specified channel.
Requires
  • The MCU with built-in ADC module.
  • Prior to using this routine, ADC module needs to be initialized. See ADCx_Init and ADCx_Init_Advanced.
  • ADC library routines require you to specify the module you want to use. To select the desired ADC module, simply change the letter x in the routine prototype for a number from 1 to 2.
  • Before using the function, be sure to configure the appropriate TRISx bits to designate pins as inputs.
Example 
unsigned adc_value;
...
adc_value = ADC1_Get_Sample(10);    // read analog value from ADC1 module channel 10
Notes
  • Number of ADC modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.
  • The function sets the appropriate bit in the ADPCFG registers to enable analog function of the chosen pin.
  • Refer to the appropriate Datasheet for channel-to-pin mapping.

ADCx_Read

Prototype

unsigned ADCx_Read(unsigned channel);
Description

The function initializes, enables ADC module and reads the specified analog channel input.
Parameters
  • channel represents the channel from which the analog value is to be acquired.
Returns

10-bit or 12-bit (depending on the MCU) unsigned value from the specified channel.
Requires
  • The MCU with built-in ADC module.
  • ADC library routines require you to specify the module you want to use. To select the desired ADC module, simply change the letter x in the routine prototype for a number from 1 to 2.
  • Number of ADC modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.
  • Before using the function, be sure to configure the appropriate TRISx bits to designate pins as inputs.
Example 
unsigned adc_value;
...
adc_value = ADC1_Read(10);    // read analog value from ADC1 module channel 10
Notes
  • This is a standalone routine, so there is no need for a previous initialization of ADC module.
  • The function sets the appropriate bit in the ADPCFG registers to enable analog function of the chosen pin.
  • Refer to the appropriate Datasheet for channel-to-pin mapping.

ADC_Set_Active

Prototype

void ADC_Set_Active(unsigned (*adc_gs)(unsigned));
Description

Sets active ADC module.
Parameters

Parameters :
Returns

Nothing.
Requires

Routine is available only for MCUs with multiple ADC modules.

Used ADC module must be initialized before using this routine. See ADCx_Init and ADCx_Init_Advanced routines.
Example 
// Activate ADC2 module
ADC_Set_Active(ADC2_Get_Sample);
Notes

None.

ADC1_ActivateCore

Prototype

void ADC1_ActivateCore(unsigned ADCCore);
Description

Sets used ADC conversion core.
Parameters
  • ADCCore: conversion core. Valid values :
    Value Description
    _ADC_SHCORE ADC Shared Core
    _ADC_CORE0 ADC Core 0
    _ADC_CORE1 ADC Core 1
    _ADC_CORE2 ADC Core 2
    _ADC_CORE3 ADC Core 3
Returns

Nothing.
Requires
  • Routine is available only for dsPIC33EPXXGS50X an dsPIC33EPXXGS202 MCUs.
  • Used ADC module must be initialized before using this routine. See ADCx_Init and ADCx_Init_Advanced routines.
Example 






Notes


    

  • This function must be called before ADCx_Get_Sample and ADCx_Read functions are used.
    • 

  • Refer to the datasheet for the ADC channel to ADC core mapping.
    • 









Library Example


This code snippet reads analog value from the channel 1 and sends readings as a text over UART1.




Copy Code To ClipboardCopy Code To Clipboard



unsigned adcRes;
char txt[6];

void main() {

  PORTB = 0x0000;
  TRISB.F1 = 1;       // set pin as input - needed for ADC to work
  ADC1_Init();
  UART1_Init(9600);

  while (1) {
    adcRes = ADC1_Get_Sample(1);
    WordToStr(adcRes, txt);
    UART1_Write_Text(txt);
    Delay_ms(50);
  }
}



HW Connection


ADC HW connection


ADC HW connection



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