SPRACN0F October 2021 – March 2023 F29H850TU , F29H859TU-Q1 , TMS320F280021 , TMS320F280021-Q1 , TMS320F280023 , TMS320F280023-Q1 , TMS320F280023C , TMS320F280025 , TMS320F280025-Q1 , TMS320F280025C , TMS320F280025C-Q1 , TMS320F280033 , TMS320F280034 , TMS320F280034-Q1 , TMS320F280036-Q1 , TMS320F280036C-Q1 , TMS320F280037 , TMS320F280037-Q1 , TMS320F280037C , TMS320F280037C-Q1 , TMS320F280038-Q1 , TMS320F280038C-Q1 , TMS320F280039 , TMS320F280039-Q1 , TMS320F280039C , TMS320F280039C-Q1 , TMS320F280040-Q1 , TMS320F280040C-Q1 , TMS320F280041 , TMS320F280041-Q1 , TMS320F280041C , TMS320F280041C-Q1 , TMS320F280045 , TMS320F280048-Q1 , TMS320F280048C-Q1 , TMS320F280049 , TMS320F280049-Q1 , TMS320F280049C , TMS320F280049C-Q1 , TMS320F28374D , TMS320F28374S , TMS320F28375D , TMS320F28375S , TMS320F28375S-Q1 , TMS320F28376D , TMS320F28376S , TMS320F28377S , TMS320F28377S-Q1 , TMS320F28378D , TMS320F28378S , TMS320F28379D , TMS320F28379D-Q1 , TMS320F28379S , TMS320F28384D , TMS320F28384S , TMS320F28386D , TMS320F28386S , TMS320F28388D , TMS320F28388S , TMS320F28P650DH , TMS320F28P650DK , TMS320F28P650SH , TMS320F28P650SK , TMS320F28P659DH-Q1 , TMS320F28P659DK-Q1 , TMS320F28P659SH-Q1
Shadow registers are used as a temporary location for active registers until a load event occurs that enables the transfer of its content into the active registers at a strategic point within the PWM cycle. This shadow to active load feature prevents corruption and spurious operation due to registers being asynchronously modified by software. Traditionally, the load events that cause a transfer of content from shadow to active registers are configured for each register individually. However, when global load mode is enabled (GLDCTL[GLD] =1), the transfer of contents from shadow register to active register occurs at the same event (GLDCTL[GLDMODE]) for all registers with this mode enabled. Critical PWM registers for submodules such as the Time-Base, Action Qualifier, and Deadband can be enabled to use the global load feature through the GLDCFG register. Additionally, the number of load strobe events that need to occur before the active registers are updated GLDCTL[GLDPRD] can also be configured to meet application needs.
If the control ISR is asynchronous to the PWM switching frequency, the one-shot load mode feature is required to ensure all the registers within a PWM module are updated only once all of the required PWM parameters have been updated. The one-shot load mode is enabled through the GLDCTL[OSHTMODE] register. When GLDCTL2[OSHTLD] is set to one, the transfer of contents from shadow to active registers, for registers that are configured to use the global load mechanism, will occur on the next event selected by GLDCTL[GLDMODE]. After the shadow to active load event happens anymore global load events will be blocked until GLDCTL2[OSHTLD] is set to one again. #FIG_GFL_PXJ_DRB is an example of the one-shot load mode action.
For variable frequency applications, there is a need for simultaneous writes of period and compare registers between ePWM modules. The EPWMXLINK register provides the capability to update the period and compare registers across multiple PWM modules by creating links between them. To further expand upon this, the global load mode register GLDCTL2 which allows for a reload or force of the one-shot load mode can also be linked between modules. This creates a scheme in which the period and compare registers can all be updated at the same time with the same value across multiple PWM modules.