UPD17708 datasheet(195/358 Pages) RENESAS

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193

µPD17704, 17705, 17707, 17708, 17709

14. A/D CONVERTER

14.1 Outline of A/D Converter

Figure 14-1 outlines the A/D converter.

The A/D converter converts an analog voltage input to the AD5 to AD0 pins into an 8-bit digital signal.

Two modes can be selected by using the ADCMD flag: software mode and hardware mode.

In the software mode, a voltage input to a pin is compared with an internal reference voltage, and the result

of the comparison is detected by the ADCCMP flag. By judging this result in software and by sequentially

selecting reference voltages, the A/D converter can be used as a successive approximation A/D converter.

In the hardware mode, reference voltages are automatically selected, and the input voltage is directly

detected as 8-bit digital data.

Figure 14-1. Outline of A/D Converter

Remarks 1. ADCCH2 through ADCCH0 (bits 2 through 0 of A/D converter channel selection register: refer

to Figure 14-3) select pins used for the A/D converter.

2. ADCCMP (bit 0 of A/D converter mode selection register: refer to Figure 14-5) detects the

result of comparison.

3. ADCSTT (bit 1 of A/D converter mode selection register: refer to Figure 14-5) detects the

operating status.

4. ADCMD (bit 2 of A/D converter mode selection register: refer to Figure 14-5) selects software

or hardware mode.

P1C3/AD5

P1C2/AD4

P0D3/AD3

P0D2/AD2

P0D1/AD1

P0D0/AD0

ADCCH2 flag

ADCCH1 flag

ADCCH0 flag

Input selection

block

Compare voltage

generation block

R-string

D/A converter

DBF

ADCMD flag

ADCCMP flag

ADCSTT flag

Start/stop control

block

Compare block

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