NEC PD78P214 Manuale Utente

225

The 

µPD78214 contains an analog-to-digital (A/D) converter with eight multiplexed analog input pins (AN0 through

AN7).

This A/D converter uses successive approximation  The conversion result is stored in an 8-bit A/D conversion result
register (ADCR).  Conversion can be performed at high speed (with conversion time of 30 

µs and at f

CLK

 = 6 MHz)

and with high accuracy.

The A/D converter can be started in the following two modes:

°

  Hardware start:  Conversion starts on a trigger input (INTP5).

°

  Software start:  Conversion starts as specified in the A/D converter mode register (ADM).

Once started, the A/D converter operates in either of the following modes:

°

  Scan mode:  Analog inputs are sequentially selected for A/D conversion from all the input pins.

°

  Select mode:  Only one input pin is used.  Analog signals are successively input from this pin to the converter.

These start and operating modes are specified by the ADM register.  The ADM register is also used to stop
conversion.

When the conversion result is sent to the ADCR register, an interrupt request (INTAD) is generated (except in the
select mode started by software).  Therefore, the conversion result can be successively sent to the memory by
using a macro service.

Hardware start

Software start

Scan mode

°

°

Select mode

°

—

Fig. 8-1 shows the configuration of the A/D converter.