Texas Instruments TMS320x28xx, 28xxx Time-Base Submodule Registers, Bits Name Value Description

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Time-Base Submodule Registers

4.1Time-Base Submodule Registers

Figure 4-1through Figure 4-5and Table 4-1through Table 4-5provide the time-base register definitions.

Figure 4-1. Time-Base Period Register (TBPRD)

15 0

TBPRD

R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

	Table 4-1. Time-Base Period Register (TBPRD) Field Descriptions
Bits Name	Value Description

15-0 TBPRD 0000-

FFFF

These bits determine the period of the time-base counter. This sets the PWM frequency.

Shadowing of this register is enabled and disabled by the TBCTL[PRDLD] bit. By default this register is shadowed.

∙If TBCTL[PRDLD] = 0, then the shadow is enabled and any write or read will automatically go to the shadow register. In this case, the active register will be loaded from the shadow register when the time-base counter equals zero.

∙If TBCTL[PRDLD] = 1, then the shadow is disabled and any write or read will go directly to the active register, that is the register actively controlling the hardware.

∙The active and shadow registers share the same memory map address.

	Figure 4-2. Time-Base Phase Register (TBPHS)
15	0

TBPHS

R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

		Table 4-2. Time-Base Phase Register (TBPHS) Field Descriptions
Bits	Name	Value Description
15-0	TBPHS	0000- These bits set time-base counter phase of the selected ePWM relative to the time-base that is

FFFFsupplying the synchronization input signal.

∙If TBCTL[PHSEN] = 0, then the synchronization event is ignored and the time-base counter is not loaded with the phase.

∙If TBCTL[PHSEN] = 1, then the time-base counter (TBCTR) will be loaded with the phase (TBPHS) when a synchronization event occurs. The synchronization event can be initiated by the input synchronization signal (EPWMxSYNCI) or by a software forced synchronization.

Figure 4-3. Time-Base Counter Register (TBCTR)

15 0

TBCTR

R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

		Table 4-3. Time-Base Counter Register (TBCTR) Field Descriptions
Bits	Name	Value Description
15-0	TBCTR	0000- Reading these bits gives the current time-base counter value.
		FFFF

Writing to these bits sets the current time-base counter value. The update happens as soon as the write occurs; the write is NOT synchronized to the time-base clock (TBCLK) and the register is not shadowed.

94 Registers SPRU791D–November 2004–Revised October 2007

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