Each ePWM module can be configured to use or ignore the synchronization input. If the TBCTL[PHSEN] bit
is set, then the time-base counter (TBCTR) of the ePWM module will be automatically loaded with the phase
register (TBPHS) contents when one of the following conditions occur:
•
EPWMxSYNCI: Synchronization Input Pulse:
The value of the phase register is loaded into the counter
register when an input synchronization pulse is detected (TBPHS → TBCTR). This operation occurs on the
next valid time-base clock (TBCLK) edge. The source of the EPWMSYNCI pulse is selected by setting a
GPIO to the EPWMSYNCI option per the GPIO Mux.
The delay from internal master module to slave modules is given by:
– if ( TBCLK = SYSCLKOUT): 2 x SYSCLKOUT
– if ( TBCLK != SYSCLKOUT):1 TBCLK
•
Software Forced Synchronization Pulse:
Writing a 1 to the TBCTL[SWFSYNC] control bit invokes a
software forced synchronization. This pulse is ORed with the synchronization input signal, and therefore has
the same effect as a pulse on EPWMxSYNCI.
•
Digital Compare Event Synchronization Pulse:
DCAEVT1 and DCBEVT1 digital compare events can be
configured to generate synchronization pulses which have the same affect as EPWMxSYNCI.
This feature enables the ePWM module to be automatically synchronized to the time base of another 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
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
for more
details on synchronization strategies.
3.2.2.4 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
System Control and
Interrupts
section of this manual. 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 device-specific version of the
System
Control and Interrupts
section.
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.
Enhanced Pulse Width Modulator (ePWM) Module
256
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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