7220 Datasheet, PDF (89/303 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

FUNCTIONAL DESCRIPTION
2.9 A-D comparator
Table 2.9.1 Relationship between contents of A-D control register 2 and reference voltage “Vref”
A-D control register 2
Internal analog voltage
bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
(comparison voltage Vref)
0
0
0
0
0
0
1/128VCC
0
0
0
0
0
1
3/128VCC
0
0
0
0
1
0
5/128VCC
:
:
:
:
:
:
:
1
1
1
1
0
1
123/128VCC
1
1
1
1
1
0
125/128VCC
1
1
1
1
1
1
127/128VCC
A-D Control Register 1
b7 b6 b5 b4 b3 b2 b1 b0
A-D control register 1 (AD1) [Address 00EE16]
B
Name
0 Analog input pin selection
to bits
2 (ADM0, ADM1, ADM2)
Functions
b2 b1 b0
0 0 0 : A-D1
0 0 1 : A-D2
0 1 0 : A-D3
0 1 1 : A-D4
1 0 0 : A-D5
1 0 1 : A-D6
1 1 0 : _{Do not set.}
1 1 1:
After reset R W
0 _RW
3 Nothing is assigned. This bit is a write disable bit.
When this bit is read out, the value is “0.”
4 ^{Storage bit of comparison}
result (ADM4)
0: Input voltage < reference voltage
1: Input voltage > reference voltage
5 _{Nothing is assigned. These bits are write disable bits.}
to _{When these bits are read out, the values are “0.”}
7
0 _R—
Indeterminate R W
0 _R—
Fig. 2.9.2 A-D control register 1 (address 00EE16)
A-D Control Register 2
b7 b6 b5 b4 b3 b2 b1 b0
A-D control register 2(AD2) [Address 00EF16]
B
Name
0 D-A converter set bits
to (ADC0, ADC1, ADC2,
5 ADC3, ADC4, ADC5)
Functions
b5 b4 b3 b2 b1 b0
0 0 0 0 0 0 : 1/128Vcc
0 0 0 0 0 1 : 3/128Vcc
0 0 0 0 1 0 : 5/128Vcc
After reset R W
0
RW
1 1 1 1 0 1 : 123/128Vcc
1 1 1 1 1 0 : 125/128Vcc
1 1 1 1 1 1 : 127/128Vcc
6, 7 Nothing is assigned. These bits are write disable bits.
When these bits are reed out, the values are “ 0.”
0
R—
Fig. 2.9.3 A-D control register 2 (address 00EF16)
2-62
7220 Group User’s Manual