AtXmega и Hi-Res (High-Resolution Extension). Можно ли при такте 32 МГц получить разрешение ШИМ 8000 единиц при соотношении частот 1:1000 (выход PWM 32 кГц) чтобы значения ШИМ 3999 и 4000 имели разницу 0,0125% в коэффициенте заполнения? Цитата (XMEGA AU [MANUAL], 210 page):
- Increases waveform generator resolution up to 8x (3 bits);
- Supports frequency, single-slope PWM, and dual-slope PWM generation;
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The high-resolution (hi-res) extension can be used to increase the resolution of the waveform generation output from a
timer/counter by four or eight. It can be used for a timer/counter doing frequency, single-slope PWM, or dual-slope PWM
generation. It can also be used with the AWeX if this is used for the same timer/counter.
The hi-res extension uses the peripheral 4x clock (ClkPER4).
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When the hi-res extension is enabled, the timer/counter must run from a non-prescaled peripheral clock. The
timer/counter will ignore its two least-significant bits (lsb) in the counter, and counts by four for each peripheral clock
cycle. Overflow/underflow and compare match of the 14 most-significant bits (msb) is done in the timer/counter. Count
and compare of the two lsb is handled and compared in the hi-res extension running from the peripheral 4x clock.
The two lsb of the timer/counter period register must be set to zero to ensure correct operation. If the count register is
read from the application code, the two lsb will always be read as zero, since the timer/counter run from the peripheral
clock. The two lsb are also ignored when generating events.
When the hi-res plus feature is enabled, the function is the same as with the hi-res extension, but the resolution will
increase by eight instead of four. This also means that the 3 lsb are handled by the hi-res extension instead of 2 lsb, as
when only hi-res is enabled. The extra resolution is achieved by counting on both edges of the peripheral 4x clock.
The hi-res extension will not output any pulse shorter than one peripheral clock cycle; i.e., a compare value lower than
four will have no visible output.
De_User (14.01.2014 23:59 - 15.01.2014 00:08, просмотров: 3000)