Adc noise canceler function – Rainbow Electronics AT90LS4433 User Manual
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AT90S/LS4433
1042G–AVR–09/02
Figure 47. ADC Timing Diagram, Single Conversion
Figure 48. ADC Timing Diagram, Free Run Conversion
ADC Noise Canceler
Function
The ADC features a Noise Canceler that enables conversion during Idle mode to reduce
noise induced from the CPU core. To make use of this feature, the following procedure
should be used:
1.
Make sure that the ADC is enabled and is not busy converting. Single Conver-
sion mode must be selected and the ADC conversion complete interrupt must be
enabled. Thus:
ADEN = 1
ADSC = 0
ADFR = 0
ADIE = 1
2.
Enter Idle mode. The ADC will start a conversion once the CPU has been halted.
3.
If no other interrupts occur before the ADC conversion completes, the ADC inter-
rupt will wake up the MCU and execute the ADC conversion complete interrupt
routine.
1
2
3
4
5
6
7
8
9
10
11
12
13
Sign and MSB of Result
LSB of Result
ADC Clock
ADSC
ADIF
ADCH
ADCL
Cycle Number
1
2
One Conversion
Next Conversion
3
Sample & Hold
MUX and REFS
Update
Conversion
complete
MUX and REFS
Update
11
12
13
MSB of Result
LSB of Result
ADC Clock
ADSC
Hold Strobe
ADIF
ADCH
ADCL
Cycle Number
1
2
One Conversion
Next
Conversion