CHAPTER 12 10-BIT A/D CONVERTER (
µ
PD789114, 789134 SUBSERIES)
User’s Manual U13045EJ2V0UM00
155
Figure 12-4. Basic Operation of 10-Bit A/D Converter
A/D conversion continues until bit 7 (ADCS0) of A/D converter mode register 0 (ADM0) is reset (0) by software.
If an attempt is made to write to ADM0 or A/D input select register 0 (ADS0) during A/D conversion, the ongoing
A/D conversion is canceled. In this case, A/D conversion is restarted from the beginning, if ADCS0 is set (1).
RESET input makes A/D conversion result register 0 (ADCR0) undefined.
12.4.2 Input voltage and conversion result
The relationships between the analog input voltage at the analog input pins (ANI0 to ANI3) and the A/D conversion
result (A/D conversion result register 0 (ADCR0)) are represented by:
ADCR0 = INT (
×
1,024 + 0.5)
or
(ADCR0 – 0.5)
×
≤
V
IN
< (ADCR0 + 0.5)
×
INT( ):
Function that returns the integer part of a parenthesized value
V
IN
:
Analog input voltage
AV
DD
:
A/D converter supply voltage
ADCR0: Value in A/D conversion result register 0 (ADCR0)
Figure 12-5 shows the relationships between the analog input voltage and the A/D conversion result.
AV
DD
1,024
V
IN
AV
DD
AV
DD
1,024
Conversion
time
Sampling
time
Sampling
A/D conversion
Undefined
Conversion
result
Conversion
result
A/D converter
operation
SAR
ADCR0
INTAD0
Содержание mPD789101
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