Interfacing adc

1. Interfacing ADCInterfacing ADC

2. What is ADC?What is ADC?
ADC – analog to digital conversion
It converts the given analog value to a
digital value
There are lot of digital ICs available to
convert analog to digital
In microcontroller interfacing the
frequently used ICs are 0804 and 0808

3. 0804 – an ADC0804 – an ADC

4. Interfacing ADCInterfacing ADC

5. Working of ADCWorking of ADC
For every interfacing initialization is
needed,
For ADC the initial values are
INTR=1; // interrupt for completion of ADC
process
rd=1; // read from 0804
wr=1; // start conversion write..

6. Working of ADC contd.Working of ADC contd.
Next step is to start the process of
converting analog voltage to digital data
By changing the state of the write pin – a
transition from 0 to 1 will start the
conversion.
End of conversion will be acknowledged
by a change in the INTR state…
See the timing diagram of the conversion
starts

7. Timing diagram of START Conv.Timing diagram of START Conv.

8. Reading the data Reading the data
To read the data from 0804 the read pin
state must be ‘0’.
After reading the data read pin must be
change back into ‘1’
The data obtained from the 0804 will be
from ‘0’ to ‘255’ , since the ADC is a 8 bit
adc and obtained value will be inbetween
2
0
to 2
8
.

9. Timing diagram of reading from Timing diagram of reading from
08040804

10. Assignment Assignment
Convert analog and display in LCD
Find the room temperature and display
the degree Celsius value in LCD.