AVR analog-to-digital (AD) conversion example program

1. Development Language

This example was developed using WinAVR/GCC 20050214 version

2. Example Description

This program simply demonstrates how to use the ADC analog-to-digital converter of ATMEGA16. Common single-ended input, differential input and calibration, reference voltage calibration, query mode, interrupt mode, data format conversion. In order to simplify the program, various data are not output to the outside. It is recommended to use the JTAG ICE hardware emulator when learning.

3. Circuit diagram design:

To simplify the circuit design, the ATmega16 function board from this website was used.

In the example, the internal 2.56V voltage reference is selected as Vref, and the differential channel is magnified 10 times
. The single-ended voltage measurement range is 02.56V, resolution is 2.5mV.
The differential voltage measurement range is +/- 256mV, resolution is 0.5mV.
Current resolution = 50uA@10 ohm current sampling resistor
Current resolution = 500uA@1 ohm current sampling resistor
In the program, the measured reference voltage needs to be substituted into the constant Vref to obtain a more accurate result
The sample I have is measured to be 2.556V@Vcc=5.0V
2.550V@Vcc=3.3V
This circuit is for reference only and does not consider the requirements for anti-interference.

.

4. Code design and description:

/******************************************************** ADC (analog-to-digital conversion) usage example ******* ******* Planning, organization and testing: Armok ***
**** Code design: HJJourAVR ******* Compiler: WINAVR20050214 ******* www.OurAVR.com 2005.8.31 ****************************************************/#include #include #include #include /*The usage of the macro INTERRUPT is similar to that of SIGNAL, the difference is that when SIGNAL is executed, the global interrupt trigger bit is cleared and other interrupts are disabled; when INTERRUPT is executed, the global interrupt trigger bit is set and other interrupts can be nested. In addition, avr-libc provides two API functions for setting and clearing the global interrupt trigger bit, which are frequently used. They are: void sei(void) and void cli(void) defined by interrupt.h*/
//Pin definition
#define in_Single 0 //PA0(ADC0)
#define in_Diff_P 3 //PA3(ADC3)
#define in_Diff_N 2 //PA2(ADC2)

//Constant definition
//Single-ended channel, no amplification
#define AD_SE_ADC0 0x00 //ADC0
#define AD_SE_ADC1 0x01 //ADC1
#define AD_SE_ADC2 0x02 //ADC2
#define AD_SE_ADC3 0x03 //ADC3
#define AD_SE_ADC4 0x04 //ADC4
#define AD_SE_ADC5 0x05 //ADC5
#define AD_SE_ADC6 0x06 //ADC6
#define AD_SE_ADC7 0x07 //ADC7

//Differential channel ADC0 as negative terminal, 10/200 times magnification
#define AD_Diff0_0_10x 0x08 //ADC0+ ADC0-, 10 times magnification, for calibration
#define AD_Diff1_0_10x 0x09 //ADC1+ ADC0-, 10 times magnification
#define AD_Diff0_0_200x 0x0A //ADC0+ ADC0-, 200 times magnification, for calibration
#define AD_Diff1_0_200x 0x0B //ADC1+ ADC0-, 200 times magnification

//Differential channel ADC2 as negative terminal, 10/200 times magnification
#define AD_Diff2_2_10x 0x0C //ADC2+ ADC2-, 10 times magnification, for calibration
#define AD_Diff3_2_10x 0x0D //ADC3+ ADC2-, 10 times magnification
#define AD_Diff2_2_200x 0x0E //ADC2+ ADC2-, 200 times magnification, for calibration
#define AD_Diff3_2_200x 0x0F //ADC3+ ADC2-, 200 times magnification

//Differential channel ADC1 is used as the negative terminal and is not amplified
#define AD_Diff0_1_1x 0x10 //ADC0+ ADC1-
#define AD_Diff1_1_1x 0x11 //ADC1+ ADC1-, for calibration
#define AD_Diff2_1_1x 0x12 //ADC2+ ADC1-
#define AD_Diff3_1_1x 0x13 //ADC3+ ADC1-
#define AD_Diff4_1_1x 0x14 //ADC4+ ADC1-
#define AD_Diff5_1_1x 0x15 //ADC5+ ADC1-
#define AD_Diff6_1_1x 0x16 //ADC6+ ADC1-
#define AD_Diff7_1_1x 0x17 //ADC7+ ADC1-

//Differential channel ADC2 is used as the negative terminal and is not amplified
#define AD_Diff0_2_1x 0x18 //ADC0+ ADC2-
#define AD_Diff1_2_1x 0x19 //ADC1+ ADC2-
#define AD_Diff2_2_1x 0x1A //ADC2+ ADC2-, for calibration
#define AD_Diff3_2_1x 0x1B //ADC3+ ADC2-
#define AD_Diff4_2_1x 0x1C //ADC4+ ADC2-
#define AD_Diff5_2_1x 0x1D //ADC5+ ADC2-

//Single-ended channel, no amplification
#define AD_SE_VBG 0x1E //VBG internal bandgap 1.22V voltage reference, for calibration
#define AD_SE_GND 0x1F //Ground calibration

//Note:
//Differential channels, if using 1x or 10x gain, 8-bit resolution is available. If using 200x gain, 7-bit resolution is available.
//Differential input channel devices in PDIP package are not tested. Devices are only guaranteed to work properly in TQFP and MLF packages.

#define Vref 2556 //mV measured Vref pin voltage @5.0V power supply
//#define Vref 2550 //mV measured Vref pin voltage @3.3V power supply

//Global variables
unsigned int ADC_SingleEnded; //ADC value of single-ended input
int ADC_Diff; //ADC value of differential input
volatile unsigned int ADC_INT_SE; //ADC value of single-ended input used in interrupt mode, will be modified in interrupt service routine,
//must be qualified by volatile
volatile unsigned char ADC_OK; //ADC status, will be modified in interrupt service routine, must be qualified by volatile
unsigned int LED_Volt; //Converted voltage mV
int LED_Curr; //Conversion