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Chapter 12
A/D Converter
User’s Manual U16504EE1V1UD00
(2)
A/D conversion result register (ADCR1)
This register holds the A/D conversion result. Each time when the A/D conversion ends, the con-
version result is loaded from the successive approximation register.
ADCR1 is read with an 8-bit memory manipulation instruction.
RESET input clears ADCR1 to 00H.
Caution:
If a write operation is executed to the A/D converter mode register (ADM1) and the
analog input channel specification register (ADS1), the contents of ADCR1 are unde-
fined. Read the conversion result before a write operation is executed to ADM1 and
ADS1. If a timing other than the above is used, the correct conversion result may not
be read.
(3)
Sample & hold circuit
The sample & hold circuit samples each analog input sequential applied from the input circuit, and
sends it to the voltage comparator. This circuit holds the sampled analog input voltage value dur-
ing A/D conversion.
(4)
Voltage comparator
The voltage comparator compares the analog input to the series resistor string output voltage.
(5)
Series resistor string
The series resistor string is in AV
DD
to AV
SS
, and generates a voltage to be compared to the ana-
log input.
(6)
ANI0 to ANI4 pins
These are five analog input pins to feed analog signals to the A/D converter. ANI0 to ANI4 are
alternate-function pins that can also be used for digital input.
Caution:
Use ANI0 to ANI4 input voltages within the specified range. If a voltage higher than
AV
DD
or lower than AV
SS
is applied (even if within the absolute maximum rating
range), the conversion value of that channel will be undefined and the conversion
values of other channels may also be affected.
(7)
AV
DD
pin (shared with AV
REF
pin)
This pin supplies the A/D converter reference voltage and is used as the power supply pin of the A/
D-converter.
It converts signals from ANI0 to ANI4 into digital signals according to the voltage applied between
AV
DD
and AV
SS
.
Keep the AV
DD
/AV
REF
pin always at the same potential as the V
DD
pin, even when the A/D-con-
verter is not used.
(8)
AV
SS
pin
This is the GND potential pin of the A/D converter. Always keep it at the same potential as the V
SS
pin even when not using the A/D converter.