Timer/PWM Module (S08TPMV3)
MC9S08QE128 MCU Series Reference Manual, Rev. 2
296
Freescale Semiconductor
16.3.5
TPM Channel Value Registers (TPMxCnVH:TPMxCnVL)
These read/write registers contain the captured TPM counter value of the input capture function or the
output compare value for the output compare or PWM functions. The channel registers are cleared by
reset.
4
MSnA
Mode select A for TPM channel n. When CPWMS=0 and MSnB=0, MSnA configures TPM channel n for
input-capture mode or output compare mode. Refer to
for a summary of channel mode and setup
controls.
Note: If the associated port pin is not stable for at least two bus clock cycles before changing to input capture
mode, it is possible to get an unexpected indication of an edge trigger.
3–2
ELSnB
ELSnA
Edge/level select bits. Depending upon the operating mode for the timer channel as set by CPWMS:MSnB:MSnA
and shown in
, these bits select the polarity of the input edge that triggers an input capture event, select
the level that will be driven in response to an output compare match, or select the polarity of the PWM output.
Setting ELSnB:ELSnA to 0:0 configures the related timer pin as a general purpose I/O pin not related to any timer
functions. This function is typically used to temporarily disable an input capture channel or to make the timer pin
available as a general purpose I/O pin when the associated timer channel is set up as a software timer that does
not require the use of a pin.
Table 16-6. Mode, Edge, and Level Selection
CPWMS
MSnB:MSnA
ELSnB:ELSnA
Mode
Configuration
X
XX
00
Pin not used for TPM - revert to general
purpose I/O or other peripheral control
0
00
01
Input capture
Capture on rising edge
only
10
Capture on falling edge
only
11
Capture on rising or
falling edge
01
01
Output compare
Toggle output on
compare
10
Clear output on
compare
11
Set output on compare
1X
10
Edge-aligned
PWM
High-true pulses (clear
output on compare)
X1
Low-true pulses (set
output on compare)
1
XX
10
Center-aligned
PWM
High-true pulses (clear
output on compare-up)
X1
Low-true pulses (set
output on compare-up)
Table 16-5. TPMxCnSC Field Descriptions (continued)
Field
Description
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Страница 174: ...MC9S08QE128 MCU Series Reference Manual Rev 2 174 Freescale Semiconductor Analog Comparator S08ACMPV3 ...
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Страница 282: ...Serial Peripheral Interface S08SPIV3 MC9S08QE128 MCU Series Reference Manual Rev 2 282 Freescale Semiconductor ...
Страница 306: ...Timer PWM Module S08TPMV3 MC9S08QE128 MCU Series Reference Manual Rev 2 306 Freescale Semiconductor ...
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