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CHAPTER 13 10-BIT A/D CONVERTER (
µ
PD780354, 780354Y SUBSERIES)
User’s Manual U15798EJ2V0UD
(6) ANI0 to ANI7 pins
These are eight analog input pins used to input analog signals to undergo A/D conversion to the A/D converter.
ANI0 to ANI7 can be used as input ports except for the pins specified as analog input by analog input channel
specification register 0 (ADS0).
Cautions 1. Use the ANI0 to ANI7 input voltages within the specification range. If a voltage higher than
or equal to AV
DD
or lower than or equal to 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.
2. Analog input (ANI0 to ANI7) pins are alternate function pins that can also be used as input
port (P10 to P17) pins. When A/D conversion is performed by selecting any one of ANI0
through ANI7, do not access port 1 during conversion, as this may cause a lower conversion
resolution.
3. When a digital pulse is applied to a pin adjacent to the pin being A/D converted, A/D
conversion values may not be obtained as expected due to coupling noise. Thus, do not
apply any pulse to a pin adjacent to the pin being A/D converted.
(7) AV
DD
pin
This pin inputs the A/D converter analog power supply.
Use this pin at the same potential as the V
DD0
or V
DD1
pin even when the A/D converter is not used.
Signals input to ANI0 to ANI7 are converted into digital signals according to the voltage applied between AV
DD
and AV
SS
.
Caution A series resistor string is connected between the AV
DD
and AV
SS
pins. Therefore, when the
output impedance of the reference voltage is too high, it seems as if the AV
DD
pin and the series
resistor string are connected in series. This may cause a greater reference voltage error.
(8) AV
SS
pin
This is the ground potential pin of the A/D converter. Always keep it at the same potential as the V
SS0
or V
SS1
pin when not using the A/D converter.
13.3 Registers to Control 10-Bit A/D Converter
The following two registers are used to control the 10-bit A/D converter.
• A/D converter mode register 0 (ADM0)
• Analog input channel specification register 0 (ADS0)
(1) A/D converter mode register 0 (ADM0)
This register sets the conversion time for the analog input to be A/D converted, conversion start/stop, and an
external trigger.
ADM0 is set by a 1-bit or 8-bit memory manipulation instruction.
RESET input sets the value of this register to 00H.
Содержание mPD780344 Series
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