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Preliminary
MC80F0104/0204
Mar. 2005 Ver 0.2
65
(3) I/O operation
The analog input pins AN0 ~ AN7,AN14 and AN15 also
have function as input/output port pins. When A/D conver-
sion is performed with any pin, be sure not to execute a
PORT input instruction with the selected pin while conver-
sion is in progress, as this may reduce the conversion res-
olution.
Also, if digital pulses are applied to a pin adjacent to the
pin in the process of A/D conversion, the expected A/D
conversion value may not be obtainable due to coupling
noise. Therefore, avoid applying pulses to pins adjacent to
the pin undergoing A/D conversion.
(4) AV
DD
pin input impedance
A series resistor string of approximately 5K
Ω
is connected
between the AV
REF
pin and the V
SS
pin. Therefore, if the
output impedance of the analog power source is high, this
will result in parallel connection to the series resistor string
between the AV
REF
pin and the V
SS
pin, and there will be
a large analog supply voltage error
Figure 14-3 A/D Block Diagram
AN0
/
AV
REF
Sample & Hold
AN1
AN7
AN14
Successive
Approximation
ADCIF
ADC Result Register
ADC
INTERRUPT
MUX
Resistor Ladder Circuit
V
DD
ADS[3:0] (ADCM[5:2])
Circuit
ADEN
ADC Result Register
ADC8
0
1
2
3
8
9
0
1
ADCRL (8-bit)
10-bit ADCR
ADCRH
0 0
ADCRL (8-bit)
ADCRH
ADCR (10-bit)
8
9
10-bit ADCR
10-bit Mode
8-bit Mode
0
1
01
AN15
AVREFS (PSR1.3)
Содержание MC80C0104
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