
232
CHAPTER 12 8-BIT A/D CONVERTER (
µ
PD780344, 780344Y SUBSERIES)
User’s Manual U15798EJ2V0UD
12.4.2 Input voltage and conversion results
The relationship between the analog voltage input to the analog input pins (ANI0 to ANI7) and the logical A/D
conversion result (stored in A/D conversion result register 1 (ADCR1)) is shown by the following expression.
ADCR1 = INT (
V
IN
×
256 + 0.5)
AV
DD
or
(ADCR1 – 0.5)
×
AV
DD
≤
V
AIN
< (ADCR1 + 0.5)
×
AV
DD
256 256
where,
INT( ):
Function which returns integer part of value in parentheses
V
AIN
:
Analog input voltage
AV
DD
:
AV
DD
pin voltage
ADCR1: A/D conversion result register 1 (ADCR1) value
Figure 12-6 shows the relationship between the analog input voltage and the A/D conversion result.
Figure 12-6. Relationship Between Analog Input Voltage and A/D Conversion Result
255
254
253
3
2
1
0
A/D conversion result
(ADCR1)
1
512
1
256
3
512
2
256
5
512
3
256
507
512
254
256
509
512
255
256
511
512
1
Input voltage/AV
DD
Содержание mPD780344 Series
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