XC2000 datasheet(102/729 Pages) INFINEON

102 / 729 page

XC2000 Derivatives

Peripheral Units (Vol. 2 of 2)

Analog to Digital Converter

Preliminary

User’s Manual

16-8

V1.0, 2007-06

ADC, UM_V0.1D6

synchronized to ADC-external events, such as timer signals or port pins. For each

request source, the user can select an input signal (from 4 possible signals

REQTRx[D:A]) as trigger input REQTRx and an input signal (from 4 possible signals

REQGTx[D:A]) as gating input REQGTx.

•

Request source 0 (1-stage sequential source) can issue a conversion request for a

single input channel. The channel number can directly be programmed.

This mechanism could be used for SW-controlled conversion requests or HW-

triggered conversions of a single input channel. If programmed with a high priority, it

can interrupt the sequences of the other request sources to inject a single

conversion.

•

Request source 1 (16-channel scan source) can issue conversion requests for a

sequence of up to 16 input channels. It can be programmed which channel takes part

in this sequence. The sequence always starts with the highest enabled channel

number and continues towards lower channel numbers (order defined by the channel

number, each channel can be converted only once per sequence).

This mechanism could be used to scan input channels permanently or on a regular

time base. For example, if programmed with a low priority, some input channels can

be scanned in a background task to update information that is not time-critical.

•

Request source 2 (4-stage sequential source) can issue a conversion request for a

sequence of up to 4 input channels. The channel numbers can be freely

programmed, especially multiple conversions of the same channel within the

sequence are supported.

This mechanism could be used to support application-specific conversion sequences

that can not be covered by the scanning mechanism of request source 1. Especially

for timing-critical sequences containing multiple conversions of the same channel,

request source 2 should be used. For example, if programmed with a medium

priority, some input channels can be converted when a specified event occurs (e.g.

synchronized to a PWM) while the scan of other input channels of the background

task (handled by request source 1) is interrupted.

XC2000 Datasheet(PDF) 102 Page - Infineon Technologies AG