Chapter 14 a/d converter, 1 a/d converter functions – NEC PD78058FY(A) User Manual

Page 261

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CHAPTER 14 A/D CONVERTER

14.1 A/D Converter Functions

The A/D converter converts an analog input into a digital value. It consists of 8 channels (ANI0 to ANI7) with an

8-bit resolution.

The conversion method is based on successive approximation and the conversion result is held in the 8-bit A/D

conversion result register (ADCR).

The following two methods are used for starting an A/D conversion operation.

(1) Hardware start

Conversion is started by trigger input (INTP3).

(2) Software start

Conversion is started by setting the A/D converter mode register (ADM).

Select 1 channel from the analog inputs ANI0 to ANI7 and execute A/D conversion. An A/D conversion operation

ends after the A/D conversion operation at hardware start is completed and an interrupt request (INTAD) is generated.

In the case of software start, the A/D conversion operation is repeated. Each time an A/D conversion ends, an interrupt

request (INTAD) is generated.

Cautions

For pins which have common functions with a port (See 3.1.1 or 4.1.1 Normal operating mode

pins, (1) Port pins), do not execute the following operations during A/D conversion. If

performed, then the general error standards cannot be maintained during A/D conversion.

<1> If it is used as a port, rewriting the output latch of its output.

<2> Even if it is not used as a port, changing the output level of pins used as outputs.

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