6.4.8 Shadow Load and Lockout Control
In capture mode, this logic inhibits (locks out) any shadow loading of CAP1 or CAP2 from APRD and ACMP
registers, respectively.
In APWM mode, shadow loading is active and two choices are permitted:
• Immediate - APRD or ACMP are transferred to CAP1 or CAP2 immediately upon writing a new value.
• On period equal, CTR[31:0] = PRD[31:0].
6.4.9 APWM Mode Operation
Main operating highlights of the APWM section:
• The time-stamp counter bus is made available for comparison by way of 2 digital (32-bit) comparators.
• When CAP1/2 registers are not used in capture mode, their contents can be used as Period and Compare
values in APWM mode.
• Double buffering is achieved via shadow registers APRD and ACMP (CAP3/4). The shadow register contents
are transferred over to CAP1/2 registers, either immediately upon a write, or on a CTR = PRD trigger.
• In APWM mode, writing to CAP1/CAP2 active registers will also write the same value to the corresponding
shadow registers CAP3/CAP4. This emulates immediate mode. Writing to the shadow registers CAP3/CAP4
will invoke the shadow mode.
• During initialization, you must write to the active registers for both period and compare. This automatically
copies the initial values into the shadow values. For subsequent compare updates, during run-time, you only
need to use the shadow registers.
APRD
TSCTR
FFFFFFFF
ACMP
0000000C
APWMx
(o/p pin)
On
time
Off−time
Period
1000h
500h
300h
Figure 6-10. PWM Waveform Details Of APWM Mode Operation
Enhanced Capture (eCAP)
440
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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