Timer_B Operation
16-10
Timer_B
Changing the Value of Period Register TBCL0
When changing TBCL0 while the timer is running and counting in the down
direction, and when the TBCL0 load event is immediate, the timer continues
its descent until it reaches zero. The value in TBCCR0 is latched into TBCL0
immediately; however, the new period takes effect after the counter counts
down to zero.
If the timer is counting in the up direction when the new period is latched into
TBCL0, and the new period is greater than or equal to the old period, or greater
than the current count value, the timer counts up to the new period before
counting down. When the timer is counting in the up direction, and the new
period is less than the current count value when TBCL0 is loaded, the timer
begins counting down. However, one additional count may occur before the
counter begins counting down.
Use of the Up/Down Mode
The up/down mode supports applications that require dead times between
output signals (see section Timer_B 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 Figure 16−9 the t
dead
is:
t
dead
=
t
timer
×
(TBCL1 − TBCL3)
With:
t
dead
Time during which both outputs need to be inactive
t
timer
Cycle time of the timer clock
TBCLx Content of compare latch x
The ability to simultaneously load grouped compare latches assures the dead
times.
Figure 16−9. Output Unit in Up/Down Mode
TBIFG
0h
TBR(max)
Output Mode 2: Toggle/Reset
Output Mode 6: Toggle/Set
TBCL0
TBCL1
EQU1
TBIFG
Interrupt Events
EQU1
EQU0
EQU1
EQU1
EQU0
TBCL3
EQU3
EQU3
EQU3
EQU3
Dead Time
Содержание MSP430x4xx Family
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Страница 348: ...8 8 16 Bit Hardware Multiplier ...
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Страница 428: ...13 10 Basic Timer1 ...
Страница 466: ...15 24 Timer_A ...
Страница 522: ...17 30 USART Peripheral Interface UART Mode ...
Страница 544: ...18 22 USART Peripheral Interface SPI Mode ...
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Страница 692: ...24 20 LCD Controller ...
Страница 746: ...26 28 ADC12 ...