atmega-adc

atmega-adc is an Arduino/Avr compatible library to control Analogic-To-Digital conversor (ADC). It supports up to 16 ADC channels.

Description

Three functions are currently provided:

• A function to read the value on an specific channel only once:

    uint16_t adc_read(uint8_t prescaler, uint8_t vref, uint8_t pin)
  

  • Where prescaler is a predefined constant to choose from:

      ADC_PRESCALER_2
      ADC_PRESCALER_4
      ADC_PRESCALER_16
      ADC_PRESCALER_32
      ADC_PRESCALER_64
      ADC_PRESCALER_128
    

  • vref is another constant needed to select voltage reference:

      ADC_VREF_AREF
      ADC_VREF_AVCC
      ADC_VREF_MISC1
      ADC_VREF_MISC2
    

  • And pin is the channel to read from: 0-7 or 0-16 if available.

• A function to read continuosly a number of channels and execute a user-defined function on every read:

    void adc_start(uint8_t prescaler, uint8_t vref, uint8_t pin_qty, void (*handler)(uint8_t, uint16_t))
  

  • prescaler and vref are the same constants as above.

  • pin_qty is the number of pins/channels to read from: 1-8 or 1-16 if available.

  • handler is the user defined function, and it should be defined as:

      void examle(uint8_t pin, uint16_t value) {
      	// code goes here
      }
    

• A function to stop the ADC

    `void adc_stop()`
  

Sample Code

• Using adc_read:

    #include <avr/io.h>
    #include "atmega-adc.h"
  
    // In this example we toggle PORTB when ADC value on channel 0 is bigger
    // than 512
  
    void main() {
    	DDRB = 0xff;
    	PORTB = 0;
    	
    	while(1) {
    		if (adc_read(ADC_PRESCALER_128, ADC_VREF_AVCC, 0) >= 512)
    			PORTB = 0xff;
    		else
    			PORTB = 0;
    	}
    }
  

• Using adc_start:

    #include <avr/io.h>
    #include "atmega-adc.h"
  
    // This sample function is called on every ADC read with 2 parameters:
    // the current pin/channel where ADC is reading and the actual value.
  
    void myfunction(uint8_t pin, uint16_t value) {
    	switch(pin) {
    		case(0):
    			// do something
    			break;
    			
    		case(1):
    			if (value >= 512)
    				PORTB = 0xff;
    			else
    				PORTB = 0;
    			break;
    			
    		case(2):
    			// do something else
    			break;
    	}
    }
  
    void main() {
    	DDRB = 0xff;
    	PORTB = 0;
    	
    	// set ADC to monitor the first 3 channels using AVCC as reference
    	adc_start(ADC_PRESCALER_128, ADC_VREF_AVCC, 3, myfunction);
    	
    	// enable global interrupts
    	sei();
    	
    	while(1) {
    		// your code goes here
    	}
    }
  

Running it in Arduino

1. Download the source code by using the Download Button on this page
2. Rename and install the library as: {arduino_path}/libraries/AtmegaADC
3. Open Arduino and go to "Import Library" option. Choose AtmegaADC from menu.

Atmel Model Support

It should work with a long range of devices, for example:

• atmega48, 88, 168, 328
• atmega164, 324, 644, 1284
• atmega640, 1280, 1281, 2560, 2561
• atmega325, 645
• ...