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CHAPTER 13 A/D CONVERTER
User’s Manual U12697EJ3V0UM
13.4.2 Input voltage and conversion result
The relationship between the analog input voltage input to the analog input pins (ANI0 to ANI7) and the A/D
conversion result (value saved in the A/D conversion result register (ADCR)) is expressed by the following equation.
ADCR = INT (
×
256 + 0.5)
or
(ADCR – 0.5)
×
≤
V
IN
< (ADCR + 0.5)
×
Remark
INT( ): Function returning the integer portion of the value in parentheses
V
IN
:
Analog input voltage
AV
DD
:
AV
DD
pin voltage
ADCR: A/D conversion result register (ADCR) value
Figure 13-5 shows the relationship between analog input voltage and the A/D conversion result.
Figure 13-5. Relationship Between Analog Input Voltage and A/D Conversion Result
V
IN
AV
DD
1
512
1
256
3
512
2
256
5
512
3
256
507
512
254
256
509
512
255
256
511
512
1
255
254
253
3
2
1
0
A/D conversion
result
(ADCR)
Input voltage/AV
DD
AV
DD
256
AV
DD
256