C167CS datasheet(349/517 Pages) INFINEON

349 / 517 page

C167CS

Derivatives

The Pulse Width Modulation Module

User’s Manual

17-8

V2.0, 2000-07

Single Shot Mode

Single shot mode is selected by setting the respective bit PSx in register PWMCON1 to

‘1’. This mode is available for PWM channels 2 and 3.

In this mode the timer PTx of the respective PWM channel is started via software and is

counting up until it reaches the value in the associated period shadow register. Upon the

next count pulse the timer is cleared to 0000H and stopped via hardware, i.e. the

respective PTRx bit is cleared. The PWM output signal is switched to high level when

the timer contents are equal to or greater than the contents of the pulse width shadow

i.e. is below the pulse width shadow register. Thus starting a PWM timer in single shot

mode produces one single pulse on the respective port pin, provided that the pulse width

value is between 0000H and the period value. In order to generate a further pulse, the

timer has to be started again via software by setting bit PTRx.

After starting the timer (i.e. PTRx = ‘1’) the output pulse may be modified via software.

Writing to timer PTx changes the positive and/or negative edge of the output signal,

depending on whether the pulse has already started (i.e. the output is high) or not (i.e.

the output is still low). This (multiple) retriggering is always possible while the timer is

running, i.e. after the pulse has started and before the timer is stopped.

Loading counter PTx directly with the value in the respective PPx shadow register will

abort the current PWM pulse upon the next clock pulse (counter is cleared and stopped

by hardware).

By setting the period (PPx), the timer start value (PTx) and the pulse width value (PWx)

appropriately, the pulse width (tw) and the optional pulse delay (td) may be varied in a

wide range.

C167CS Datasheet(PDF) 349 Page - Infineon Technologies AG