HMS87C5216 Datasheet, PDF (74/76 Pages) List of Unclassifed Manufacturers – CMOS SINGLE-CHIP 8-BIT MICROCONTROLLER FOR UR(Universal Remocon) & WIRELESS KEYBOARD

HMS87C5216
ADMR
A/D Control Register
-
ANEN ADAN3 ADAN2 ADAN1 ADAN0 ADST
ADF
ADDRESS : F4H
RESET VALUE : --000001
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)
A/D Status bit
0 : A/D Conversion is in process
1 : A/D Conversion is completed
A/D Start bit
1 : A/D Conversion is started
After 1 cycle, cleared to “0”
0 : Bit force to zero
ADCR
A/D Result Data Register
A/D Enable bit
1 : A/D Conversion is enable
0 : A/D Converter module shut off
and consumes no operation current
ADCR7 ADCR6 ADCR5 ADCR4 ADCR3 ADCR2 ADCR1 ADCR0
ADDRESS : F5H
RESET VALUE : Undefined
Figure 19-2 A/D Converter Registers
ENABLE A/D CONVERTER
A/D INPUT CHANNEL SELECT
ANALOG REFERENCE SELECT
A/D START (ADST = 1)
A/D Converter Cautions
(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.
NOP
ADSF = 1
NO
YES
READ ADCR
Figure 19-3 A/D Converter Operation Flow
Analog
Input
100~1000pF
AN0~AN3
Figure 19-4 Analog Input Pin Connecting Capacitor
(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
SEP. 2004 Ver 1.01