3.2.7.2 Controlling and Monitoring the Trip-Zone Submodule
The trip-zone submodule operation is controlled and monitored through the following registers:
Table 3-17. Trip-Zone Submodule Registers
Register
Address Offset
Shadowed
Description
Bit Description
TZSEL
0x0012
No
Trip-Zone Select Register
TZDCSEL
0x0013
No
Trip-zone Digital Compare Select Register
TZCTL
0x0014
No
Trip-Zone Control Register
TZEINT
0x0015
No
Trip-Zone Enable Interrupt Register
TZFLG
0x0016
No
Trip-Zone Flag Register
TZCLR
0x0017
No
Trip-Zone Clear Register
TZFRC
0x0018
No
Trip-Zone Force Register
(1)
All trip-zone registers are EALLOW protected and can be modified only after executing the EALLOW instruction. For more information,
see the
System Control and Interrupts
chapter.
(2)
This register is discussed in more detail in
.
3.2.7.3 Operational Highlights for the Trip-Zone Submodule
The following sections describe the operational highlights and configuration options for the trip-zone submodule.
The trip-zone signals TZ1 to TZ6 (also collectively referred to as TZn) are active low input signals. When one of
these signals goes low, or when a DCAEVT1/2 or DCBEVT1/2 force happens based on the TZDCSEL register
event selection, it indicates that a trip event has occurred. Each ePWM module can be individually configured
to ignore or use each of the trip-zone signals or DC events. Which trip-zone signals or DC events are used by
a particular ePWM module is determined by the TZSEL register for that specific ePWM module. The trip-zone
signals may or may not be synchronized to the system clock (SYSCLKOUT) and digitally filtered within the GPIO
MUX block. A minimum of 3*TBCLK low pulse width on TZn inputs is sufficient to trigger a fault condition on
the ePWM module. If the pulse width is less than this, the trip condition may not be latched by CBC or OST
latches. The asynchronous trip makes sure that if clocks are missing for any reason, the outputs can still be
tripped by a valid event present on TZn inputs . The GPIOs or peripherals must be appropriately configured. For
more information, see the
System Control and Interrupts
chapter.
Each TZn input can be individually configured to provide either a cycle-by-cycle or one-shot trip event for
an ePWM module. DCAEVT1 and DCBEVT1 events can be configured to directly trip an ePWM module or
provide a one-shot trip event to the module. Likewise, DCAVET2 and DCBEVT2 events can also be configured
to directly trip an ePWM module or provide a cycle-by-cycle trip event to the module. This configuration is
determined by the TZSEL[DCAEVT1/2], TZSEL[DCBEVT1/2], TZSEL[CBCn], and TZSEL[OSHTn] control bits
(where n corresponds to the trip input) respectively.
•
Cycle-by-Cycle (CBC):
When a cycle-by-cycle trip event occurs, the action specified in the TZCTL[TZA] and
TZCTL[TZB] bits is carried out immediately on the EPWMxA and/or EPWMxB output.
possible actions. In addition, the cycle-by-cycle trip event flag (TZFLG[CBC]) is set and a EPWMx_TZINT
interrupt is generated if it is enabled in the TZEINT register and PIE peripheral.
If the CBC interrupt is enabled via the TZEINT register, and DCAEVT2 or DCBEVT2 are selected as CBC trip
sources via the TZSEL register, it is not necessary to also enable the DCAEVT2 or DCBEVT2 interrupts in
the TZEINT register, as the DC events trigger interrupts through the CBC mechanism.
The specified condition on the inputs is automatically cleared when the ePWM time-base counter reaches
zero (TBCTR = 0x0000) if the trip event is no longer present. Therefore, in this mode, the trip event is cleared
or reset every PWM cycle. The TZFLG[CBC] flag bit will remain set until it is manually cleared by writing to
the TZCLR[CBC] bit. If the cycle-by-cycle trip event is still present when the TZFLG[CBC] bit is cleared, then
it will again be immediately set.
Enhanced Pulse Width Modulator (ePWM) Module
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
287
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