HMS87C5216 ETC1 [List of Unclassifed Manufacturers], HMS87C5216 Datasheet - Page 74

• Manufacturer Part Number: HMS87C5216
• Description: CMOS SINGLE-CHIP 8-BIT MICROCONTROLLER FOR UR(Universal Remocon) & WIRELESS KEYBOARD
• Manufacturer: ETC1 [List of Unclassifed Manufacturers]

HMS87C5216
Figure 19-3 A/D Converter Operation Flow
ADMR
ADCR
ANALOG REFERENCE SELECT
A/D INPUT CHANNEL SELECT
ENABLE A/D CONVERTER
A/D START (ADST = 1)
A/D Control Register
A/D Result Data Register
ADCR7
READ ADCR
ADSF = 1
-
NOP
YES
ADCR6
ANEN
ADAN3
ADCR5
NO
Figure 19-2 A/D Converter Registers
ADAN2
ADCR4
A/D Enable bit
1 : A/D Conversion is enable
0 : A/D Converter module shut off
Analog Channel Select
0000 : Channel 0 (R1[4]/AN0)
0001 : Channel 1 (R1[5]/AN1)
0010 : Channel 2 (R1[6]/AN2)
0011 : Channel 3 (R1[7]/AN3)
and consumes no operation current
ADAN1
ADCR3
ADAN0
ADCR2
(1) Input range of AN0 to AN3
The input voltage of AN0 to AN3 should be within the specifica-
tion range. In particular, if a voltage above VDD or below Vss is
input (even if within the absolute maximum rating range), the
conversion value for that channel can not be indeterminate. The
conversion values of the other channels may also be affected.
(2) Noise countermeasures
In order to maintain 8-bit resolution, attention must be paid to
noise on pins VDD and AN0 to AN3. Since the effect increases
in proportion to the output impedance of the analog input source,
it is recommended that a capacitor be connected externally as
shown in Figure 19-4 in order to reduce noise.
(3) Pins AN0/R1[4] and AN1/R1[5] to AN3/R1[7]
The analog input pins AN0 to AN3 also function as input/output
port (PORT R1 ) pins. When A/D conversion is performed with
A/D Converter Cautions
Figure 19-4 Analog Input Pin Connecting Capacitor
Analog
Input
ADCR1
ADST
100~1000pF
ADCR0
A/D Start bit
1 : A/D Conversion is started
0 : Bit force to zero
ADF
After 1 cycle, cleared to “0”
A/D Status bit
0 : A/D Conversion is in process
1 : A/D Conversion is completed
ADDRESS : F5H
RESET VALUE : Undefined
ADDRESS : F4H
RESET VALUE : --000001
SEP. 2004 Ver 1.01
AN0~AN3