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0h
0FFFFh
TAIFG
Output Mode 2: Toggle/Reset
Output Mode 6: Toggle/Set
TAxCCR0
TAxCCR1
EQU1
TAIFG
Interrupt Events
EQU1
EQU0
EQU1
EQU1
EQU0
TAxCCR2
EQU2
EQU2
EQU2
EQU2
Dead Time
Timer_A Operation
11.2.3.5 Use of Up/Down Mode
The up/down mode supports applications that require dead times between output signals (see section
Timer_A Output Unit
). For example, to avoid overload conditions, two outputs driving an H-bridge must
never be in a high state simultaneously. In the example shown in
, the t
dead
is:
t
dead
= t
timer
× (
–
)
Where:
t
dead
= Time during which both outputs need to be inactive
t
timer
= Cycle time of the timer clock
TAxCCRn = Content of capture/compare register n
The TAxCCRn registers are not buffered. They update immediately when written to. Therefore, any
required dead time is not maintained automatically.
Figure 11-9. Output Unit in Up/Down Mode
11.2.4 Capture/Compare Blocks
Up to seven identical capture/compare blocks, TAxCCRn (where n = 0 to 7), are present in Timer_A. Any
of the blocks may be used to capture the timer data or to generate time intervals.
11.2.4.1 Capture Mode
The capture mode is selected when CAP = 1. Capture mode is used to record time events. It can be used
for speed computations or time measurements. The capture inputs CCIxA and CCIxB are connected to
external pins or internal signals and are selected with the CCIS bits. The CM bits select the capture edge
of the input signal as rising, falling, or both. A capture occurs on the selected edge of the input signal. If a
capture occurs:
•
The timer value is copied into the TAxCCRn register.
•
The interrupt flag CCIFG is set.
The input signal level can be read at any time via the CCI bit. Devices may have different signals
connected to CCIxA and CCIxB. See the device-specific data sheet for the connections of these signals.
The capture signal can be asynchronous to the timer clock and cause a race condition. Setting the SCS
bit synchronizes the capture with the next timer clock. Setting the SCS bit to synchronize the capture
signal with the timer clock is recommended (see
).
341
SLAU272C – May 2011 – Revised November 2013
Timer_A
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