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CHAPTER 11 10-BIT A/D CONVERTER ( µ µ µ µ PD789436 AND 789456 SUBSERIES)
11.3 10-Bit A/D Converter Control Registers
The 10-bit A/D converter is controlled by the following two registers.
• A/D converter mode register 0 (ADM0)
• Analog input channel specification register 0 (ADS0)
(1)
A/D converter mode register 0 (ADM0)
ADM0 specifies the conversion time for analog inputs. It also specifies whether to enable conversion.
ADM0 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets ADM0 to 00H.
Symbol
<7>
6
ADM0
ADCS0
0
ADCS0
0
Conversion disabled
1
Conversion enabled
FR02
FR01
0
0
0
0
0
1
1
0
1
0
1
1
Other than above
Notes 1. The specifications of FR02, FR01, and FR00 must be such that the A/D conversion time is at
least 14 µ s.
2. These bit combinations must not be used, as the A/D conversion time will fall below 14 µ s.
Cautions 1. Bits 0 to 2 and 6 must be set to 0.
2. The result of conversion performed immediately after setting ADCS0 is undefined.
3. The conversion result may be undefined after clearing ADCS0.
Remarks 1. f
: Main system clock oscillation frequency
X
2. The parenthesized values apply to operation at f
200
Figure 11-2. Format of A/D Converter Mode Register 0
5
4
3
FR02
FR01
FR00
A/D conversion control
FR00
µ
0
144/f
(28.8 s)
X
µ
1
120/f
(24 s)
X
µ
0
96/f
(19.2 s)
X
µ
0
72/f
(14.4 s)
X
1
60/f
(Setting prohibited
X
0
48/f
(Setting prohibited
X
Setting prohibited
User's Manual U15075EJ1V0UM00
2
1
0
0
0
0
A/D conversion time selection
Note 2
)
Note 2
)
= 5.0 MHz.
X
Address
After reset
R/W
FF80H
00H
R/W
Note 1
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