HMS87C1808B Datasheet, PDF (61/99 Pages) List of Unclassifed Manufacturers – 8-BIT SINGLE-CHIP MICROCONTROLLERS

HMS87C1X04B/08B/16B
ADCM
ADCR
A/D Control Register
-
-
ADEN
ADS2
ADS1
ADS0
ADST
ADSF
ADDRESS : EAH
RESET VALUE : --00_0001
Reserved
Analog Channel Select
000 : Channel 0 (RB0/AN0)
001 : Channel 1 (RA1/AN1)
010 : Channel 2 (RA2/AN2)
011 : Channel 3 (RA3/AN3)
100 : Channel 4 (RA4/AN4)
101 : Channel 5 (RA5/AN5)
110 : Channel 6 (RA6/AN6)
111 : Channel 7 (RA7/AN7)
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
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 : EBH
RESET VALUE : Undefined
Figure 15-2 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 AN7
The input voltage of AN0 to AN7 should be within the specifica-
tion range. In particular, if a voltage above VDD (or AVref) or be-
low VSS is input (even if within the absolute maximum rating
range), the conversion value for that channel can not be determi-
nate. The conversion values of the other channels may also be af-
fected.
(2) Noise countermeasures
In order to maintain 8-bit resolution, attention must be paid to
noise on pins AVref (or VDD) and AN0 to AN7. Since the effect
increases in proportion to the output impedance of the analog in-
put source, it is recommended that a capacitor be connected ex-
ternally as shown in Figure 15-4 in order to reduce noise.
NOP
ADSF = 1
NO
YES
READ ADCR
Figure 15-3 A/D Converter Operation Flow
Analog
Input
100~1000pF
AN0~AN7
Figure 15-4 Analog Input Pin Connecting Capacitor
(3) Pins AN0/RB0 and AN1/RA1 to AN7/RA7
The analog input pins AN0 to AN7 also function as input/output
SEP. 2004 Ver 1.03
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