SPRS230M – OCTOBER 2003 – REVISED MARCH 2011
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4.3
Hi-Resolution PWM (HRPWM)
The HRPWM module offers PWM resolution (time granularity) which is significantly better than what can
be achieved using conventionally derived digital PWM methods. The key points for the HRPWM module
are:
• Significantly extends the time resolution capabilities of conventionally derived digital PWM
• Typically used when effective PWM resolution falls below ~ 9–10 bits. This occurs at PWM frequencies
greater than ~200 kHz when using a CPU/System clock of 100 MHz.
• This capability can be utilized in both duty cycle and phase-shift control methods.
• Finer time granularity control or edge positioning is controlled via extensions to the Compare A and
Phase registers of the ePWM module.
• HRPWM capabilities are offered only on the A signal path of an ePWM module (i.e., on the EPWMxA
output). EPWMxB output has conventional PWM capabilities.
4.4
Enhanced CAP Modules (eCAP1/2/3/4)
The 280x device contains up to four enhanced capture (eCAP) modules.
shows a functional
block diagram of a module. See the
TMS320x280x, 2801x, 2804x Enhanced Capture (eCAP) Module
Reference Guide
(literature number
for more details.
The eCAP modules are clocked at the SYSCLKOUT rate.
The clock enable bits (ECAP1/2/3/4ENCLK) in the PCLKCR1 register are used to turn off the eCAP
modules individually (for low power operation). Upon reset, ECAP1ENCLK, ECAP2ENCLK,
ECAP3ENCLK, and ECAP4ENCLK are set to low, indicating that the peripheral clock is off.
58
Peripherals
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