HD64F36022 datasheet(249/384 Pages) RENESAS

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Section 14 A/D Converter

Rev. 4.00 Sep. 23, 2005 Page 223 of 354

REJ09B0025-0400

14.4

Operation

The A/D converter operates by successive approximation with 10-bit resolution. It has two

operating modes; single mode and scan mode. When changing the operating mode or analog input

channel, in order to prevent incorrect operation, first clear the bit ADST to 0 in ADCSR. The

ADST bit can be set at the same time as the operating mode or analog input channel is changed.

14.4.1

Single Mode

In single mode, A/D conversion is performed once for the analog input on the specified single

channel as follows:

A/D conversion is started from the first channel when the ADST bit in ADCSR is set to 1,

according to software or external trigger input.

When A/D conversion is completed, the result is transferred to the corresponding A/D data

On completion of conversion, the ADF bit in ADCSR is set to 1. If the ADIE bit is set to 1 at

this time, an ADI interrupt request is generated.

The ADST bit remains set to 1 during A/D conversion. When A/D conversion ends, the

ADST bit is automatically cleared to 0 and the A/D converter enters the wait state.

14.4.2

Scan Mode

In scan mode, A/D conversion is performed sequentially for the analog input on the specified

channels (four channels maximum) as follows:

1. When the ADST bit is set to 1 by software, or external trigger input, A/D conversion starts on

the first channel in the group.

2. When A/D conversion for each channel is completed, the result is sequentially transferred to

the A/D data register corresponding to each channel.

3. When conversion of all the selected channels is completed, the ADF flag in ADCSR is set to 1.

If the ADIE bit is set to 1 at this time, an ADI interrupt is requested. Conversion of the first

channel in the group starts again.

4. The ADST bit is not automatically cleared to 0. Steps [2] to [3] are repeated as long as the

ADST bit remains set to 1. When the ADST bit is cleared to 0, A/D conversion stops.

HD64F36022 Datasheet(PDF) 249 Page - Renesas Technology Corp