CP3BT23 Datasheet, PDF (192/260 Pages) Texas Instruments – CP3BT23 Reprogrammable Connectivity Processor with Bluetooth and Dual CAN Interfaces

The two I/O pins associated with a timer subsystem function
as independent PWM outputs in the dual 8-bit PWM mode.
If a PWM timer is stopped using its associated
MODE.TxRUN bit the following actions result:
Figure 105 illustrates the configuration of a timer subsystem
while operating in 16-bit PWM mode. The numbering in
Figure 105 refers to timer subsystem 1 but equally applies
to the other three timer subsystems.
! The associated TIOx pin will return to its default value as
defined by the IOxCTL.PxPOL bit.
! The counter will stop and will retain its last value.
! Any pending updates of the PERCAPx and DTYCAPx
register will be completed.
! The prescaler counter will be stopped and reset if both
7
0
C1PRSC
==
Prescaler
Counter
TMOD1 = 10
MODE.TxRUN bits are cleared.
Figure 104 illustrates the configuration of a timer subsystem
T1RUN
while operating in dual 8-bit PWM mode. The numbering in
15
0
Figure 104 refers to timer subsystem 1 but equally applies
[15:0]
Count1[15:0]
to the other three timer subsystems.
7
0
C1PRSC
==
Prescaler
Counter
TMOD1 = 01
Restart
Compare
PERCAP1[15:0]
Compare
DTYCAP1[15:0]
te ^T2RUN
T1RUN
RQ
RQ
15
Res ^COUNT1[15:8]
0
[15:8]
le ^Compare
PERCAP1[15:8]
7
Res ^COUNT1[7:0]
Compare
PERCAP1[7:0]
0
[7:0]
S
S
P2POL
TIO2
P1POL
TIO1
DS091
Figure 105. VTU 16-bit PWM Mode
Compare
DTYCAP1[15:8]
o _{R Q}
S
Compare
DTYCAP1[7:0]
RQ
S
26.1.3 Dual 16-Bit Capture Mode
In addition to the two PWM modes, each timer subsystem
may be configured to operate in an input capture mode
which provides two 16-bit capture channels. The input cap-
ture mode can be used to precisely measure the period and
duty cycle of external signals.
s _P2POL
TIO2
P1POL
TIO1
DS090
b Figure 104. VTU Dual 8-Bit PWM Mode
26.1.2 16-Bit PWM Mode
Each of the four timer subsystems may be independently
configured to provide a single 16-bit PWM channel. In this
O ^{case the lower and upper bytes of the counter are concate-}
In capture mode the counter COUNTx operates as a 16-bit
up-counter while the two TIOx pins associated with a timer
subsystem operate as capture inputs. A capture event on
the TIOx pins causes the contents of the counter register
(COUNTx) to be copied to the PERCAPx or DTYCAPx reg-
isters respectively.
Starting the counter is identical to the 16-bit PWM mode, i.e.
setting the lower of the two MODE.TxRUN bits will start the
counter and the clock prescaler. In addition, the capture
nated to form a single 16-bit counter.
event inputs are enabled once the MODE.TxRUN bit is set.
Operation in 16-bit PWM mode is conceptually identical to
the dual 8-bit PWM operation as outlined under Dual 8-bit
PWM Mode on page 190. The 16-bit timer may be started
or stopped with the lower MODE.TxRUN bit, i.e. T1RUN for
timer subsystem 1.
The two TIOx outputs associated with a timer subsystem
can be used to produce either two identical PWM wave-
forms or two PWM waveforms of opposite polarities. This
can be accomplished by setting the two PxPOL bits of the
respective timer subsystem to either identical or opposite
values.
The TIOx capture inputs can be independently configured to
detect a capture event on either a positive transition, a neg-
ative transition or both a positive and a negative transition.
In addition, any capture event may be used to reset the
counter COUNTx and the clock prescaler counter. This
avoids the need for software to keep track of timer overflow
conditions and greatly simplifies the direct frequency and
duty cycle measurement of an external signal.
191
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