TMS320F2810, TMS320F2811, TMS320F2812
TMS320C2810, TMS320C2811, TMS320C2812
www.ti.com
SPRS174T – APRIL 2001 – REVISED MAY 2012
4.2.1
General-Purpose (GP) Timers
There are two GP timers. The GP timer x (x = 1 or 2 for EVA; x = 3 or 4 for EVB) includes:
•
A 16-bit timer, up-/down-counter, TxCNT, for reads or writes
•
A 16-bit timer-compare register, TxCMPR (double-buffered with shadow register), for reads or writes
•
A 16-bit timer-period register, TxPR (double-buffered with shadow register), for reads or writes
•
A 16-bit timer-control register, TxCON, for reads or writes
•
Selectable internal or external input clocks
•
A programmable prescaler for internal or external clock inputs
•
Control and interrupt logic, for four maskable interrupts: underflow, overflow, timer compare, and period
interrupts
•
A selectable direction input pin (TDIRx) (to count up or down when directional up-/down-count mode is
selected)
The GP timers can be operated independently or synchronized with each other. The compare register
associated with each GP timer can be used for compare function and PWM-waveform generation. There
are three continuous modes of operations for each GP timer in up- or up/down-counting operations.
Internal or external input clocks with programmable prescaler are used for each GP timer. GP timers also
provide the time base for the other event-manager submodules: GP timer 1 for all the compares and PWM
circuits, GP timer 2/1 for the capture units and the quadrature-pulse counting operations. Double-buffering
of the period and compare registers allows programmable change of the timer (PWM) period and the
compare/PWM pulse width as needed.
4.2.2
Full-Compare Units
There are three full-compare units on each event manager. These compare units use GP timer1 as the
time base and generate six outputs for compare and PWM-waveform generation using programmable
deadband circuit. The state of each of the six outputs is configured independently. The compare registers
of the compare units are double-buffered, allowing programmable change of the compare/PWM pulse
widths as needed.
4.2.3
Programmable Deadband Generator
Deadband generation can be enabled/disabled for each compare unit output individually. The deadband-
generator circuit produces two outputs (with or without deadband zone) for each compare unit output
signal. The output states of the deadband generator are configurable and changeable as needed by way
of the double-buffered ACTRx register.
4.2.4
PWM Waveform Generation
Up to eight PWM waveforms (outputs) can be generated simultaneously by each event manager: three
independent pairs (six outputs) by the three full-compare units with programmable deadbands, and two
independent PWMs by the GP-timer compares.
4.2.5
Double Update PWM Mode
The F281x and C281x Event Manager supports “Double Update PWM Mode.” This mode refers to a PWM
operation mode in which the position of the leading edge and the position of the trailing edge of a PWM
pulse are independently modifiable in each PWM period. To support this mode, the compare register that
determines the position of the edges of a PWM pulse must allow (buffered) compare value update once at
the beginning of a PWM period and another time in the middle of a PWM period. The compare registers in
F281x and C281x Event Managers are all buffered and support three compare value reload/update (value
in buffer becoming active) modes. These modes have earlier been documented as compare value reload
conditions. The reload condition that supports double update PWM mode is reloaded on Underflow
(beginning of PWM period) OR Period (middle of PWM period). Double update PWM mode can be
achieved by using this condition for compare value reload.
Copyright © 2001–2012, Texas Instruments Incorporated
Peripherals
61
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