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OutlineAnalog to Digital Conversion

Coding ADC

Using ADC on Firebird-V Robot

E-Yantra TeamEmbedded Real-Time Systems Lab

Indian Institute of Technology-Bombay

IIT BombaySeptember 26, 2012

www.e-yantra.org Firebird ATmega2560 Robotics Research Platform 1/19
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Coding ADC

Agenda for Discussion

1 Analog to Digital ConversionNeed for ADCADC of ATmega2560

ADC Channels

2 Coding ADCADC InitilizationADCSRA

ADCSRBADMUXACSRProgram


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Coding ADC

Need for ADCADC of ATmega2560ADC Channels

Need for ADC

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Coding ADC


Need for ADC

IR Proximity sensors

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Need for ADC


Sharp IR Range sensors

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Need for ADC



white line sensors

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Need for ADC



white line sensors

battery voltage sensing

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Need for ADC



white line sensors

battery voltage sensing

etc..

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In-Built ADC of ATmega2560

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10-bit Resolution


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10-bit Resolution

13 - 260 s Conversion Time

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10-bit Resolution


16 Multiplexed Single Ended Input Channels

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10-bit Resolution



14 Differential input channels

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10-bit Resolution




Optional Left Adjustment for ADC Result Readout

0 - VCC ADC Input Voltage Range

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10-bit Resolution






2.7 - VCC Differential ADC Voltage Range


O li N d f ADC
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10-bit Resolution







Selectable 2.56V or 1.1V ADC Reference Voltage


O tli N d f ADC
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Coding ADC



10-bit Resolution







Selectable 2.56V or 1.1V ADC Reference Voltage Free Running or Single Conversion Mode


Outline Need for ADC
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Coding ADC



10-bit Resolution







Selectable 2.56V or 1.1V ADC Reference Voltage Free Running or Single Conversion Mode

Interrupt on ADC Conversion Complete


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ADC Channels


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Coding ADC


ADC Channels

Pin No. Pin Name Description97 PF0/ADC0 ADC input for Battery Voltage Monitoring96 PF1/ADC1 ADC input for White Line Sensor 3(Right)95 PF2/ADC2 ADC input for White Line Sensor 2(Center)94 PF3/ADC3 ADC input for White Line Sensor 1(Left)93 PF4/ADC4 ADC input for IR proximity analog sensor 1

92 PF5/ADC5 ADC input for IR proximity analog sensor 291 PF6/ADC6 ADC input for IR proximity analog sensor 390 PF7/ADC7 ADC input for IR proximity analog sensor 489 PK0/ADC8 ADC input for IR proximity analog sensor 588 PK1/ADC9 ADC input for Sharp IR range sensor 187 PK2/ADC10 ADC input for Sharp IR range sensor 286 PK3/ADC11 ADC input for Sharp IR range sensor 385 PK4/ADC12 ADC input for Sharp IR range sensor 484 PK5/ADC13 ADC input for Sharp IR range sensor 583 PK6/ADC14 ADC input for Servo Pod 182 PK7/ADC15 ADC input for Servo Pod 2


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Analog to Digital ConversionCoding ADC

ADC of ATmega2560ADC Channels

ADC Channels

Pin No. Pin Name Description97 PF0/ADC0 ADC input for Battery Voltage Monitoring96 PF1/ADC1 ADC input for White Line Sensor 3(Right)95 PF2/ADC2 ADC input for White Line Sensor 2(Center)94 PF3/ADC3 ADC input for White Line Sensor 1(Left)93 PF4/ADC4 ADC input for IR proximity analog sensor 1

92 PF5/ADC5 ADC input for IR proximity analog sensor 291 PF6/ADC6 ADC input for IR proximity analog sensor 390 PF7/ADC7 ADC input for IR proximity analog sensor 489 PK0/ADC8 ADC input for IR proximity analog sensor 588 PK1/ADC9 ADC input for Sharp IR range sensor 187 PK2/ADC10 ADC input for Sharp IR range sensor 286 PK3/ADC11 ADC input for Sharp IR range sensor 385 PK4/ADC12 ADC input for Sharp IR range sensor 484 PK5/ADC13 ADC input for Sharp IR range sensor 583 PK6/ADC14 ADC input for Servo Pod 182 PK7/ADC15 ADC input for Servo Pod 2


Outline

ADC InitilizationADCSRAADCSRB
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Steps for Using ADC in AVR


OutlineADC InitilizationADCSRAADCSRB
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1 Enabling ADC :Set the ADEN bit of the ADC Control and Status Register ADCSRAto logic 1.

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OutlineA l t Di it l C i


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ADMUXACSRProgram



2 ADC Prescaler Division Ratio :

Set the bits ADPS 2:0 of the Register ADCSRA. ADC needs clockfrequency between 50KHz to 200KHz

3 Selecting reference voltage source for the ADC :Select the reference voltage for ADC as AREF by makingREFS1:REFS0 as 00 (5 V)



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ADMUXACSRProgram



2 ADC Prescaler Division Ratio :

Set the bits ADPS 2:0 of the Register ADCSRA. ADC needs clockfrequency between 50KHz to 200KHz

3 Selecting reference voltage source for the ADC :Select the reference voltage for ADC as AREF by makingREFS1:REFS0 as 00 (5 V)

4 Left/Right Adjustment :ADCH contains the two most significant bits and ADCL containsthe remaining eight bits. We left shift this data so that ADCH willcontain the eight bits including the MSB and ADCL will containremaining two LSBs




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ADMUXACSRProgram

ADC Initilization



ADC InitilizationADCSRAADCSRBADMUX
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ADMUXACSRProgram

ADC Initilization

To Program ADC, we have to initialize some register before use it.



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g gCoding ADC

ADMUXACSRProgram

ADC Initilization


These registers are:



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g gCoding ADC

ADMUXACSRProgram

ADC Initilization



1 ADCSRA- ADC Control and Status Register A



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Coding ADCADMUXACSRProgram

ADC Initilization




2 ADCSRB- ADC Control and Status Register B



C di ADC

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Coding ADCADMUXACSRProgram

ADC Initilization





3 ADMUX- ADC Multiplexer Selection Register



C di ADC


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Coding ADCACSRProgram

ADC Initilization






4 ACSR - Analog Comparator Control and Status Register



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ADC Initilization






4 ACSR - Analog Comparator Control and Status Register

All these Registers are 8 Bit.



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ADCSRA- ADC Control and Status Register AThis register is Used to control ADC operation



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ADC InitilizationADCSRAADCSRBADMUXACSR

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Bit Symbol Description Bit Value



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gACSRProgram



7 ADEN ADC Enable



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gACSRProgram



7 ADEN ADC Enable 1



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ACSRProgram



7 ADEN ADC Enable 1

6 ADSC ADC Start Conversion



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ACSRProgram



7 ADEN ADC Enable 1

6 ADSC ADC Start Conversion 0



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Program



7 ADEN ADC Enable 1


5 ADATE ADC Auto Trigger Enable



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Program



7 ADEN ADC Enable 1


5 ADATE ADC Auto Trigger Enable 0



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Program



7 ADEN ADC Enable 1


5 ADATE ADC Auto Trigger Enable 04 ADIF ADC Interrupt Flag



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ADC InitilizationADCSRAADCSRBADMUXACSRP
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Program



7 ADEN ADC Enable 1


5 ADATE ADC Auto Trigger Enable 04 ADIF ADC Interrupt Flag 0



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ADC InitilizationADCSRAADCSRBADMUXACSRP
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Program



7 ADEN ADC Enable 1



3 ADIE ADC Interrupt Enable



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ADC InitilizationADCSRAADCSRBADMUXACSRProgram
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Program



7 ADEN ADC Enable 1



3 ADIE ADC Interrupt Enable 0



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Program



7 ADEN ADC Enable 1




2 ADPS2 ADC Prescaler Select Bits



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Program



7 ADEN ADC Enable 1




2 ADPS2 ADC Prescaler Select Bits 1



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ADC Initilization

ADCSRAADCSRBADMUXACSRProgram
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g



7 ADEN ADC Enable 1








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ADC Initilization

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g



7 ADEN ADC Enable 1








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ADC Initilization

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7 ADEN ADC Enable 1









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ADC Initilization

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7 ADEN ADC Enable 1









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ADC Initilization

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7 ADEN ADC Enable 1









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ADC Initilization


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7 ADEN ADC Enable 1







ADCSRA= 0x86



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ADC Initilization

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ADC Prescaler Selection Bit



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ADC Initilization

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ADC Prescaler Selection Bit



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ADC Initilization

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ADCSRB- ADC Control and Status Register BThis register is Used to control ADC operation



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ADC Initilization

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ADC Initilization


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7 - Reserved Bit



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ADC Initilization

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7 - Reserved Bit -



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ADC Initilization


ADCSRB ADC C l d S R i B
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7 - Reserved Bit -

6 ACME Analog Comparator Multiplexer Enable



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ADC Initilization



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7 - Reserved Bit -

6 ACME Analog Comparator Multiplexer Enable 0



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ADC Initilization



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7 - Reserved Bit -


5 - Reserved Bit -4 - Reserved Bit -



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ADC Initilization


ADCSRB ADC C t l d St t R i t B
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7 - Reserved Bit -



3 MUX5 ADC Channel selection bit-5



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ADC Initilization


ADCSRB ADC C t l d St t R i t B

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7 - Reserved Bit -



3 MUX5 ADC Channel selection bit-5 0



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ADC Initilization


ADCSRB ADC Control and Status Register B
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7 - Reserved Bit -




2 ADTS2 ADC Auto Trigger Source Bits 0





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ADC Initilization


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7 - Reserved Bit -









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ADC Initilization


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7 - Reserved Bit -







ADCSRB= 0x00



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ADC Initilization


ADMUX ADC Multiplexer Selection Register
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ADMUX - ADC Multiplexer Selection RegisterThis register is Used to select ADC channel



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ADC Initilization


ADMUX - ADC Multiplexer Selection Register
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ADMUX - ADC Multiplexer Selection RegisterThis register is Used to select ADC channel




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ADC Initilization


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ADMUX ADC Multiplexer Selection RegisterThis register is Used to select ADC channel


7 REFS1 Reference Selection Bit



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ADC Initilization


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7 REFS1 Reference Selection Bit 0




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ADC Initilization


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5 ADLAR ADC Left Adjust Result



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ADC Initilization



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5 ADLAR ADC Left Adjust Result 1



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U C u t p e e Se ect o eg steThis register is Used to select ADC channel




5 ADLAR ADC Left Adjust Result 14 MUX4 ADC Channel selection bit-4



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p gThis register is Used to select ADC channel




5 ADLAR ADC Left Adjust Result 14 MUX4 ADC Channel selection bit-4 0







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5 ADLAR ADC Left Adjust Result 14 MUX4 ADC Channel selection bit-4 0







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5 ADLAR ADC Left Adjust Result 1






ADMUX=0x20



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ADC Reference Voltage Selection Bit
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g



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ADC Reference Voltage Selection Bit
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OutlineAnalog to Digital ConversionCoding ADC


ADC Left Adjustment Bit

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ADC Left Adjustment Bit
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ADC InitilizationADCSRA


ADMUX5:0 Channel Selection
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MUX5:0 ADC Channel

00000 ADC0

00001 ADC1

00010 ADC200011 ADC3

00100 ADC4

00101 ADC5

00110 ADC600111 ADC7






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MUX5:0 ADC Channel

00000 ADC0

00001 ADC1

00010 ADC200011 ADC3

00100 ADC4

00101 ADC5

00110 ADC600111 ADC7






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MUX5:0 ADC Channel

00000 ADC0

00001 ADC1

00010 ADC200011 ADC3

00100 ADC4

00101 ADC5

00110 ADC6

00111 ADC7

MUX5:0 ADC Channel

10000 ADC8

10001 ADC9

10010 ADC1010011 ADC11

10100 ADC12

10101 ADC13

10110 ADC14

10111 ADC15





ACSR - Analog Comparator Control and Status RegisterThis register is Used for Analog Comparator
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This register is Used for Analog Comparator





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This register is Used for Analog Comparator






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g U g p


7 ACD Analog Comparator Disable

www e-yantra org Firebird ATmega2560 Robotics Research Platform 15/19




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g g p


7 ACD Analog Comparator Disable 1





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g g p



6 ACBG Analog Comparator Bandgap Select 0

5 ACO Analog Comparator Output 0

4 ACI Analog Comparator Interrupt Flag 0

3 ACIE Analog Comparator Interrupt Enable 0

2 ACIC Analog Comparator Input Capture Enable 0

1 ACIS1 Analog Comparator Interrupt Mode Select 0






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ACSR=0x80

www e yantra org Firebird ATmega2560 Robotics Research Platform 15/19


Coding ADC



Syntax for C-ProgramADC Initialization
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Coding ADC



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ADC Port Pin Config



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ADC Port Pin Config

void adc_pin_config (void) //Configure ADC Ports{

Port K and Port F must be defined Input

}



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ADC Port Pin Config



}

ADC Initialization



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ADC Port Pin Config



}

ADC Initialization

void adc_init() //Set Register Values for starting ADC{

ADCSRA =

ADCSRB =ADMUX =ADCSRA =ACSR =

}



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ADC Port Pin Config



}

ADC Initialization

void adc_init() //Set Register Values for starting ADC{

ADCSRA =

ADCSRB =ADMUX =ADCSRA =ACSR =

}

t Fi bi d AT 2560 R b ti R h Pl tf 16/19


Coding ADC



Syntax for C-ProgramProgram
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Outline




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Main Program


Outline




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Main Program

int main(void){

init_devices();lcd_init();while(1){

print_sensor(1,1,0);

print_sensor(1,4,1);print_sensor(1,8,2);

}}


Outline




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Main Programint main(void){




}}

Print ADC Value on LCD


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Main Programint main(void){




}}

Print ADC Value on LCD

void print_sensor(char row, char column, unsigned char channel){

ADC_Value = ADC_Conversion(channel);lcd_print(row, column, ADC_Value, 3);

}


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ADC Conversion Function


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ADC Conversion Functionunsigned char ADC_Conversion(unsigned char Ch){

unsigned char a;if(Ch>7)

{ADCSRB = 0x08;

}Ch = Ch & 0x07;ADMUX= 0x20 | Ch;ADCSRA = ADCSRA | 0x40; //Set start conversion bitwhile((ADCSRA&0x10)==0); //Wait for ADC conversion to completea=ADCH;ADCSRA = ADCSRA|0x10; //clear ADIF (ADC Interrupt Flag) by writing 1 to itADCSRB = 0x00;return a;

}


Outline



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07-ADC