1.1 Purpose of the Trip-Zone Submodule
2 Challenge of Multiple Trip-Zones
Trip-Zone Introduction
Figure 1. Trip-Zone Submodule
Each ePWM module is connected to six TZn signals (TZ1 to TZ6) that are sourced from the
general-purpose input/output (GPIO) MUX. These signals indicate external fault or trip conditions, and the
ePWM outputs can be programmed to respond accordingly when faults occur.
The key functions of the trip-zone submodule are:
• Trip inputs TZ1 to TZ6 can be flexibly mapped to any ePWM module.
• Upon a fault condition, outputs EPWMxA and EPWMxB can be forced to one of the following:
– High
– Low
– High-impedance
– No action taken
• Support for one-shot trip (OSHT) for major short circuits or over-current conditions
• Support for cycle-by-cycle tripping (CBC) for current limiting operation
• Each trip-zone input pin can be allocated to either one-shot or cycle-by-cycle operation.
• Interrupt generation is possible on any trip-zone pin.
• Software-forced tripping is also supported.
• The trip-zone submodule can be fully bypassed if it is not required.
Each ePWM output (EPWMxA and EPWMxB) can be sourced by any or all of the six TZn inputs (TZ1 to
TZ6). Since there is only one TZ flag for a selected TZ type (one-shot or cycle-by-cycle), the source of the
TZ event can not be determined if multiple TZs are enabled for a single ePWM output. One solution is to
enable all the TZ interrupts.
Since all TZs share PIE group 2, the code could read PIEIFR2 to determine which TZ’s flag is set upon
entry into the interrupt service routine. The problem is that the hardware automatically clears the
PIEIFRx.y bit when fetching the interrupt vector from the PIE, and before entry into the ISR; so the TZ
source identifier is lost. A flowchart of the hardware interrupt response is shown in the TMS320x280x,
2801x, 2804x System Control and Interrupts Reference Guide (SPRU712).
Configuring Source of Multiple ePWM Trip-Zone Events2 SPRAAR4–October 2007
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