UPD784224 Datasheet, PDF (37/92 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCONTROLLERS

µPD784224, 784225, 784224Y, 784225Y
7.5 A/D Converter
An A/D converter converts an analog input variable into a digital signal. This microcontroller is provided with
an A/D converter with a resolution of 8 bits and 8 channels (ANI0 to ANI7).
This A/D converter is of successive approximation type and the result of conversion is stored to an 8-bit A/D
conversion result register (ADCR).
The A/D converter can be started in the following two ways:
• Hardware start
Conversion is started by trigger input (P03).
• Software start
Conversion is started by setting the A/D converter mode register.
One analog input channel is selected from ANI0 to ANI7 for A/D conversion. When A/D conversion is started
by means of hardware start, conversion is stopped after it has been completed. When conversion is started by
means of software start, A/D conversion is repeatedly executed, and each time conversion has been completed,
an interrupt request (INTAD) is generated.
Figure 7-7. Block Diagram of A/D Converter
ANI0
ANI1
ANI2
ANI3
ANI4
ANI5
ANI6
ANI7
Sample & hold circuit
Series resistor string
Voltage comparator
AVDD
Successive approximation
register (SAR)
AVSS
INTP3/P03
Edge
detector
Controller
INTAD
Edge
detector
A/D conversion result register
(ADCR)
Internal bus
INTP3
Data Sheet U12376EJ1V0DS00
37