Robo India in this PPT is explaining on the most crucial and important aspect of Embedded system, robotics, automation and physical computing. Analog to digital conversion is required in almost every project of above mentioned domain. One advantage to use a AVR micro controller is that it has inbuilt ADC thus we donot need to use external system for ADC. Here Robo India is teaching how to use ADC in AVR series microcontrollers. We welcome your views and queries, we are found at- website: http://roboindia.com mail- info@roboindia.com

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5. SIGNAL
DISCRETE CONTINOUS
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6. • Are all CONTINUOUS time signals ANALOG ?
• All continuous time signals are analog but all
analog signals are not continuous time
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7. ANALOG
Cont. Time
Discrete
Time
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8. • The ADC converts an analog input
voltage to a 10-bit digital value through
successive approximation.
• The minimum value represents GND
and the maximum value represents the
voltage on the AREF pin minus 1 LSB
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9. 𝐴𝐷𝐶 =
𝑉𝑖𝑛 . 1024
𝑉 𝑟𝑒𝑓
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10. Signal
Processing
Analog Digital Mixed
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11. • What's wrong with totally analog ?
• Ans – Two arrows in a Quiver is always
better than one
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12. A digital signal is superior to an analog
signal because it is more robust to noise
and can easily be recovered, corrected
and amplified. For this reason, the
tendency today is to change an analog
signal to digital data
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15. ReadADCX()
{
ADMUX=0x4X;
ADCSRA=0x86;
SETBIT(ADCSRA,BIT(6));
while(!(ADCSRA & (1<<ADIF)));
s=ADC;
return(s);
}
NOTE: X can take value from 0 to 7
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16. • ADMUX = 0x4X
• Let x = 1
⇒ ADMUX = 0x41 ⇒ ADMUX = 01000001
0 1 0 0 0 0 0 1
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17. • REFS1 = 0
• REFS0 = 1
0 1 0 0 0 0 0 1
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18. The ADLAR bit affects the presentation of
the ADC conversion result in the ADC Data
Register.
• ADLAR = 0 ⇒ LEFT ADJUST
• ADLAR = 1 ⇒ RIGHT ADJUST
0 1 0 0 0 0 0 1
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19. • MUX4..0 = 00001
0 1 0 0 0 0 0 1
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20. ReadADCX()
{
ADMUX=0x4X; // DONE
ADCSRA=0x86;
SETBIT(ADCSRA,BIT(6));
while(!(ADCSRA & (1<<ADIF)));
s=ADC;
return(s);
}
NOTE: X can take value from 0 to 7
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21. • ADCSRA = 0x86
• Let x = 1
⇒ ADCSRA = 0x41 ⇒ ADCSRA = 10000110
1 0 0 0 0 1 1 0
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22. • BIT 7
• ADEN ⇒ ADC Enable bit
• ADEN = 1 ⇒ Enable ADC
• ADEN = 0 ⇒ Disable ADC
1 0 0 0 0 1 1 0
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23. • BIT 6
• ADSC - Write this bit to one to start
each conversion
1 0 0 0 0 1 1 0
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24. • BIT 4
• ADIF - This bit is set when an ADC
conversion completes
1 0 0 0 0 1 1 0
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25. ADPS2..0 = 110 ⇒ Division factor is 64
1 0 0 0 0 1 1 0
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26. ReadADCX()
{
ADMUX=0x4X; // DONE
ADCSRA=0x86; // DONE
SETBIT(ADCSRA,BIT(6)); // DONE
while(!(ADCSRA & (1<<ADIF)));
s=ADC;
return(s);
}
NOTE: X can take value from 0 to 7
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