M38039G4H-XXXHP RENESAS [Renesas Technology Corp], M38039G4H-XXXHP Datasheet - Page 58

• Manufacturer Part Number: M38039G4H-XXXHP
• Description: SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
• Manufacturer: RENESAS [Renesas Technology Corp]

3803 Group (Spec.H QzROM version)
Rev.1.10
REJ03B0166-0110
A/D CONVERTER
[AD Conversion Register 1, 2 (AD1, AD2)] 0035
0038
The AD conversion register is a read-only register that stores the
result of an A/D conversion. When reading this register during an
A/D conversion, the previous conversion result is read.
Bit 7 of the AD conversion register 2 is the conversion mode
selection bit. When this bit is set to “0”, the A/D converter
becomes the 10-bit A/D mode. When this bit is set to “1”, that
becomes the 8-bit A/D mode. The conversion result of the 8-bit
A/D mode is stored in the AD conversion register 1. As for 10-bit
A/D mode, not only 10-bit reading but also only high-order 8-bit
reading of conversion result can be performed by selecting the
reading procedure of the AD conversion registers 1, 2 after A/D
conversion is completed (in Figure.50).
As for 10-bit A/D mode, the 8-bit reading inclined to MSB is
performed when reading the AD converter register 1 after A/D
conversion is started; and when the AD converter register 1 is
read after reading the AD converter register 2, the 8-bit reading
inclined to LSB is performed.
[AD/DA Control Register (ADCON)] 0034
The AD/DA control register controls the A/D conversion
process. Bits 0 to 2 and bit 4 select a specific analog input pin.
Bit 3 signals the completion of an A/D conversion. The value of
this bit remains at “0” during an A/D conversion, and changes to
“1” when an A/D conversion ends. Writing “0” to this bit starts
the A/D conversion.
• Comparison Voltage Generator
The comparison voltage generator divides the voltage between
AV
voltage in the 10-bit A/D mode (256 division in 8-bit A/D mode).
The A/D converter successively compares the comparison
voltage Vref in each mode, dividing the V
below), with the input voltage.
• 10-bit A/D mode (10-bit reading)
• 10-bit A/D mode (8-bit reading)
• 8-bit A/D mode
Vref =
Vref =
Vref =
SS
16
and V
=0
V
-------------
V
-------------
V
-------------
1024
256
256
REF
REF
REF
REF
Nov 14, 2005
× n (n = 0 − 255)
× n (n = 0 − 1023)
× n (n − 0.5) (n = 1 − 255)
into 1024, and that outputs the comparison
(n = 0)
Page 58 of 91
REF
16
voltage (see
16
,
• Channel Selector
The channel selector selects one of ports P6
P0
• Comparator and Control Circuit
The comparator and control circuit compares an analog input
voltage with the comparison voltage, and then stores the result in
the AD conversion registers 1, 2. When an A/D conversion is
completed, the control circuit sets the AD conversion completion
bit and the AD interrupt request bit to “1”.
Note that because the comparator consists of a capacitor
coupling, set f(X
conversion.
Fig 49. Structure of AD/DA control register
Fig 50. Structure of 10-bit A/D mode reading
b7
7
8-bit reading
(Read only address 0035
AD conversion register 1
(AD1: address 0035
10-bit reading
(Read address 0038
AD conversion register 2
(AD2: address 0038
AD conversion register 1
(AD1: address 0035
Note : Bits 2 to 6 of address 0038
/AN
15
to P0
0
/AN
IN )
8
, and inputs the voltage to the comparator.
to 500 kHz or more during an A/D
PRELIMINARY
Notice: This is not a final specification.
Some parametric limits are subject to change.
16
16
16
b0
16
)
)
)
before 0035
AD/DA control register
(ADCON : address 0034
Analog input pin selection bits 1
AD conversion completion bit
Analog input pin selection bit 2
Not used (returns “0” when read)
DA
DA
b2 b1 b0
16
16
0 0 0: P6
0 0 1: P6
0 1 0: P6
0 1 1: P6
1 0 0: P6
1 0 1: P6
1 1 0: P6
1 1 1: P6
0: Conversion in progress
1: Conversion completed
0: AN
1: AN
0: DA
1: DA
0: DA
1: DA
become “0” at reading.
)
b9
b7
b7
1
2
b7
b7
0
output enable bit
output enable bit
b8 b7 b6 b5 b4 b3 b2
b6 b5 b4 b3 b2 b1 b0
0
8
1
1
2
2
to AN
to AN
output disabled
output enabled
output disabled
output enabled
0
1
2
3
4
5
6
7
7
/AN
/AN
/AN
/AN
/AN
/AN
/AN
/AN
16
/AN
7
15
)
side
0 or
1 or
2 or
3 or
4 or
5 or
6 or
7 or
side
7
to P6
P0
P0
P0
P0
P0
P0
P0
P0
16
0
1
2
3
4
5
6
7
b9 b8
0
/AN
/AN
/AN
/AN
/AN
/AN
/AN
/AN
/AN
)
b0
b0
b0
8
9
10
11
12
13
14
15
0
or