C167CS datasheet(363/517 Pages) INFINEON

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C167CS

Derivatives

The Analog/Digital Converter

User’s Manual

18-6

V2.0, 2000-07

A conversion is started by setting bit ADST = ‘1’. The busy flag ADBSY will be set and

the converter then selects and samples the input channel, which is specified by the

channel selection field ADCH in register ADCON. The sampled level will then be held

internally during the conversion. When the conversion of this channel is complete, the

10-bit result together with the number of the converted channel is transferred into the

result register ADDAT and the interrupt request flag ADCIR is set. The conversion result

is placed into bitfield ADRES of register ADDAT.

If bit ADST is reset via software, while a conversion is in progress, the A/D converter will

stop after the current conversion (fixed channel modes) or after the current conversion

sequence (auto scan modes).

Setting bit ADST while a conversion is running, will abort this conversion and start a new

conversion with the parameters specified in ADCON.

Note: Abortion and restart (see above) are triggered by bit ADST changing from ‘0’ to

‘1’, i.e. ADST must be ‘0’ before being set.

While a conversion is in progress, the mode selection field ADM and the channel

selection fields ADCH and ADX may be changed. ADM will be evaluated after the

current conversion. ADCH and ADX will be evaluated after the current conversion (fixed

channel modes) or after the current conversion sequence (auto scan modes).

Note: When selecting an extension channel (AN23 … AN16) only write numbers within

the range 0 … 7 to bitfield ADCH. Higher channel numbers are not defined for

extension channels and will return invalid conversions results.

Fixed Channel Conversion Modes

These modes are selected by programming the mode selection bitfield ADM in register

ADCON to ‘00B’ (single conversion) or to ‘01B’ (continuous conversion). After starting the

converter through bit ADST the busy flag ADBSY will be set and the channel specified

in bit fields ADCH/ADX will be converted. After the conversion is complete, the interrupt

request flag ADCIR will be set.

In Single Conversion Mode the converter will automatically stop and reset bits ADBSY

and ADST.

In Continuous Conversion Mode the converter will automatically start a new

conversion of the channel specified in ADCH/ADX. ADCIR will be set after each

completed conversion.

When bit ADST is reset by software, while a conversion is in progress, the converter will

complete the current conversion and then stop and reset bit ADBSY.

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