NXP Semiconductors MWCT101 S Series, Reference Manual

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41.1.5 FTM Input Capture Options
The following channel 0 input capture source options are selected via SIM_FTMOPT1.
The external pin option is selected by default.
• FTM1 channel 0 input capture = FTM1_CH0 pin or CMP0 output
• FTM2 channel 0 input capture = FTM2_CH0 pin or CMP0 output
• FTM2 channel 1 input capture = FTM2_CH1 pin or exclusive OR of FTM2_CH0,
FTM2_CH1, and FTM1_CH1. See FTM Hall sensor support .
41.1.6 FTM Hall sensor support
For 3 phase motor control sensor-ed applications the use of Hall sensors, generally 3
sensors placed 120 degrees apart around the rotor, are deployed to detect position and
speed. Each of the 3 sensors provides a pulse that applied to an input capture pin, can
then be analyzed and both speed and position can be deduced. To simplify the
calculations required by the CPU on each hall sensor's input, if all 3 inputs are
"exclusively OR'd" into one timer channel and the free running counter is refreshed on
every edge then this can simplify the speed calculation.
Via the SIM module and SIM_FTMOPT1 register the FTM2CH1SEL bit provides the
choice of normal FTM2_CH1 input or the XOR of FTM2_CH0, FTM2_CH1 and
FTM1_CH1 pins that will be applied to FTM2_CH1.
NOTE
If the user utilizes FTM1_CH1 to be an input to FTM2_CH1,
FTM1_CH0 can still be utilized for other functions.
X O R
FTM2_CH1
FTM2_CH0
FTM1_CH1
Ch0
Ch1
FTM2
Ch0
Ch1
FTM1
SIM_FTMOPT1[FTM2CH1SEL]
Figure 41-3. FTM Hall Sensor Configuration
Chip-specific FTM information
MWCT101xS Series Reference Manual, Rev. 3, 07/2019
1124 NXP Semiconductors