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ePWM Submodules
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ePWM module. Lead or lag phase control can be added to the waveforms generated by different
ePWM modules to synchronize them. In up-down-count mode, the TBCTL[PSHDIR] bit configures the
direction of the time-base counter immediately after a synchronization event. The new direction is
independent of the direction prior to the synchronization event. The PHSDIR bit is ignored in count-up
or count-down modes. See
through
for examples.
Clearing the TBCTL[PHSEN] bit configures the ePWM to ignore the synchronization input pulse. The
synchronization pulse can still be allowed to flow-through to the EPWMxSYNCO and be used to
synchronize other ePWM modules. In this way, you can set up a master time-base (for example, ePWM1)
and downstream modules (ePWM2 - ePWMx) may elect to run in synchronization with the master. See
the Application to Power Topologies
for more details on synchronization strategies.
2.2.4
Phase Locking the Time-Base Clocks of Multiple ePWM Modules
The TBCLKSYNC bit can be used to globally synchronize the time-base clocks of all enabled ePWM
modules on a device. This bit is part of the device's clock enable registers and is described in the specific
device version of the System Control and Interrupts Reference Guide listed in
. When TBCLKSYNC = 0, the time-base clock of all ePWM modules is stopped
(default). When TBCLKSYNC = 1, all ePWM time-base clocks are started with the rising edge of TBCLK
aligned. For perfectly synchronized TBCLKs, the prescaler bits in the TBCTL register of each ePWM
module must be set identically. The proper procedure for enabling the ePWM clocks is as follows:
1. Enable the individual ePWM module clocks. This is described in the specific device version of the
System Control and Interrupts Reference Guide listed in
Related Documentation From Texas
2. Set TBCLKSYNC = 0. This will stop the time-base clock within any enabled ePWM module.
3. Configure the prescaler values and desired ePWM modes.
4. Set TBCLKSYNC = 1.
2.2.5
Time-base Counter Modes and Timing Waveforms
The time-base counter operates in one of four modes:
•
Up-count mode which is asymmetrical.
•
Down-count mode which is asymmetrical.
•
Up-down-count which is symmetrical
•
Frozen where the time-base counter is held constant at the current value
To illustrate the operation of the first three modes, the following timing diagrams show when events are
generated and how the time-base responds to an EPWMxSYNCI signal.
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TMS320x2833x, 2823x Enhanced Pulse Width Modulator (ePWM) Module
SPRUG04A – October 2008 – Revised July 2009
© 2008–2009, Texas Instruments Incorporated