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
ADCx_Init_Advanced
ADCx_Get_Sample
ADCx_Read
ADC_Set_Active

ADCx_Init

Prototype	procedure 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

procedure ADC1_Init_Advanced(Reference : word);

// dsPIC33FJ and PIC24HJ prototype

procedure ADCx_Init_Advanced(ADCMode : word; Reference : word);

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.

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 or _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	function ADCx_Get_Sample(channel : word) : word;
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	var adc_value : word; ... 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	function ADCx_Read(channel : word) : word;
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	var adc_value : word; ... 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	procedure ADC_Set_Active(adc_gs : ^TADC_Get_Sample);
Description	Sets active ADC module.
Parameters	Parameters : `adc_gs:` ADCx_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 ADCx_Init and ADCx_Init_Advanced routines.
Example	// Activate ADC2 module ADC_Set_Active(@ADC2_Get_Sample);
Notes	None.

Library Example

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

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program ADC_on_LEDs;
var ADCresult : word;
    txt : array[6]  of char;

begin
  PORTB := 0x0000;       // clear PORTB
  TRISB := 0xFFFF;       // PORTB is input
  ADC1_Init();           // Enable ADC module
  UART1_Init(9600);      // Initialize UART communication

  while (TRUE) do
    begin
      ADCresult := ADC1_Get_Sample(1);   // Acquire ADC sample
      WordToStr(ADCresult, txt);         // convert its value to string
      UART1_Write_Text(txt);             // and send it to UART terminal
      Delay_ms(50);
    end;
end.

HW Connection

ADC HW connection

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