SPRUJD3A July 2025 – October 2025 F28E120SB , F28E120SC
The following sections describe the operational highlights and configuration options for the trip-zone submodule.
The trip-zone signals TZ1 to TZ8 (also collectively referred to as TZn) are active-low input signals. When one of these signals goes low, the indication is that a trip event has occurred. Each MCPWM module can be individually configured to ignore or use each of the trip-zone signals. Note that the trip zone settings for all PWM pairs are configured by the same register bits, it is not possible to have separate trip-zone settings for separate PWM pairs within a single MCPWM module. The trip-zone signals used by a particular MCPWM module is configured by the TZSEL register for that specific MCPWM module. The trip-zone signals can be 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 MCPWM module. If the pulse width is less than this, the trip condition cannot 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 MCPWM module. This configuration is determined by the TZSEL[CBCn], and TZSEL[OSTn] control bits (where n corresponds to the trip input), respectively.
Additionally, when a cycle-by-cycle trip event occurs, the cycle-by-cycle trip event flag (INTFLAG[CBC]) is set and a PWMx interrupt is generated if the INTEN[CBC] bit is set. A corresponding flag for the specific event that caused the CBC interrupt is also set in the TZCBCOSTFLAG register, which can be cleared by writing to the corresponding flag in TZCBCOSTCLR.
The specified condition on the inputs is automatically cleared based on the selection made with INTCLR[CBC] if the trip event is no longer present. Therefore, in this mode, the trip event is cleared or reset every PWM cycle. The INTFLG[CBC] and TZCBCOSTFLAG flag bits remain set until the flag bits are manually cleared by writing to the INTCLR[CBC] and TZCBCOSTCLR flag bits. If the cycle-by-cycle trip event is still present when the INTFLG[CBC] and TZCBCOSTFLAG register bits are cleared, then these bits are again immediately set.
Additionally, when a one-shot trip event occurs, the one-shot trip event flag (INTFLG[OST]) is set and a PWMx interrupt is generated if the INTEN[OST] bit is set.. A corresponding flag for the event that caused the OST event is also set in register TZCBCOSTFLAG. The one-shot trip condition must be cleared manually by writing to the INTCLR[OST] bit. If desired, the TZCBCOSTFLAG register bit can also be cleared by manually writing to the corresponding bit in the TZCBCOSTCLR register.
The action taken when a trip event occurs can be configured individually for the A outputs and B outputs of the MCPWM module, but the action is the same across all A outputs and the same across all B outputs. Trip actions are specified by the TZCTL register. Some of the possible actions, shown in Table 15-11, can be taken on a trip event.
| TZCTL[TZx] Register Bitfield Settings | MCPWMx_yA and MCPWMx_yB | Comment |
|---|---|---|
| 0,0 | High-Impedance | Tripped |
| 0,1 | Force to High State | Tripped |
| 1,0 | Force to Low State | Tripped |
| 1,1 | No Change | Do Nothing. No change is made to the output. |