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3886 View Datasheet(PDF) - MITSUBISHI ELECTRIC

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Description
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3886
Mitsubishi
MITSUBISHI ELECTRIC  Mitsubishi
3886 Datasheet PDF : 110 Pages
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MITSUBISHI MICROCOMPUTERS
3886 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
A-D CONVERTER
[A-D Conversion Register 1,2 (AD1, AD2)]
003516, 003816
The A-D 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 A-D conversion register 2 is the conversion mode se-
lection 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 A-D conversion register 1. As for 10-bit A-D mode,
10-bit reading or 8-bit reading can be performed by selecting the
reading procedure of the A-D conversion register 1, 2 after A-D
conversion is completed (in Figure 48).
The A-D conversion register 1 performs the 8-bit reading inclined
to MSB after reset, the A-D conversion is started, or reading of the
A-D converter register 1 is generated; and the register becomes
the 8-bit reading inclined to LSB after the A-D converter register 2
is generated.
[AD/DA Control Register (ADCON)] 003416
The AD/DA control register controls the A-D conversion process.
Bits 0 to 2 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
AVSS and VREF into 1024, and outputs the divided voltages 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 VREF (see below), with the input
voltage.
• 10-bit A-D mode (10-bit reading)
Vref =
VREF
1024
!
n
(n
=
0–1023)
• 10-bit A-D mode (8-bit reading)
Vref =
VREF
256
!
n
(n
=
0–255)
• 8-bit A-D mode
Vref =
VREF
256
! (n–0.5)
(n = 1–255)
=0
(n = 0)
Channel Selector
The channel selector selects one of ports P60/AN0 to P67/AN7,
and inputs the voltage to the comparator.
Comparator and Control Circuit
The comparator and control circuit compares an analog input volt-
age with the comparison voltage, and then stores the result in the
A-D conversion registers 1, 2. When an A-D conversion is com-
pleted, the control circuit sets the A-D conversion completion bit
and the A-D interrupt request bit to “1”.
Note that because the comparator consists of a capacitor cou-
pling, set f(XIN) to 500 kHz or more during an A-D conversion.
b7
b0
AD/DA control register
(ADCON : address 003416)
Analog input pin selection bits
b2 b1 b0
0 0 0: P60/AN0
0 0 1: P61/AN1
0 1 0: P62/AN2
0 1 1: P63/AN3
1 0 0: P64/AN4
1 0 1: P65/AN5
1 1 0: P66/AN6
1 1 1: P67/AN7
A-D conversion completion bit
0: Conversion in progress
1: Conversion completed
PWM0 output pin selection bit
0: P56/PWM01
1: P30/PWM00
PWM1 output pin selection bit
0: P57/PWM11
1: P31/PWM10
DA1 output enable bit
0: DA1 output disabled
1: DA1 output enabled
DA2 output enable bit
0: DA2 output disabled
1: DA2 output enabled
Fig. 47 Structure of AD/DA control register
10-bit reading
(Read address 003816 before 003516)
b7
b0
(Address 003816) 0
b9 b8
b7
b0
(Address 003516) b7 b6 b5 b4 b3 b2 b1 b0
Note: Bits 2 to 6 of address 003816 becomes “0”at reading.
8-bit reading (Read only address 003516)
b7
b0
(Address 003516) b9 b8 b7 b6 b5 b4 b3 b2
Fig. 48 Structure of 10-bit A-D mode reading
51
 

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