C167CS datasheet(246/517 Pages) INFINEON

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C167CS

Derivatives

The General Purpose Timer Units

User’s Manual

10-18

V2.0, 2000-07

The reload mode triggered by T3OTL can be used in a number of different

configurations. Depending on the selected active transition the following functions can

be performed:

• If both a positive and a negative transition of T3OTL is selected to trigger a reload, the

core timer will be reloaded with the contents of the auxiliary timer each time it

overflows or underflows. This is the standard reload mode (reload on overflow/

underflow).

• If either a positive or a negative transition of T3OTL is selected to trigger a reload, the

core timer will be reloaded with the contents of the auxiliary timer on every second

overflow or underflow.

• Using this “single-transition” mode for both auxiliary timers allows to perform very

flexible pulse width modulation (PWM). One of the auxiliary timers is programmed to

reload the core timer on a positive transition of T3OTL, the other is programmed for a

reload on a negative transition of T3OTL. With this combination the core timer is

alternately reloaded from the two auxiliary timers.

Figure 10-13 shows an example for the generation of a PWM signal using the alternate

reload mechanism. T2 defines the high time of the PWM signal (reloaded on positive

transitions) and T4 defines the low time of the PWM signal (reloaded on negative

transitions). The PWM signal can be output on T3OUT with T3OE = ‘1’, port latch = ‘1’

and direction bit = ‘1’. With this method the high and low time of the PWM signal can be

varied in a wide range.

Note: The output toggle latch T3OTL is accessible via software and may be changed, if

required, to modify the PWM signal.

However, this will NOT trigger the reloading of T3.

C167CS Datasheet(PDF) 246 Page - Infineon Technologies AG