STMicroelectronics STM32F405, Reference Manual

Page: 547 / 1731

DocID018909 Rev 11 547/1731
RM0090 Advanced-control timers (TIM1&TIM8)
581
Figure 127. Example of counter operation in encoder interface mode.
Figure 128 gives an example of counter behavior when TI1FP1 polarity is inverted (same
configuration as above except CC1P=’1’).
Figure 128. Example of encoder interface mode with TI1FP1 polarity inverted.
The timer, when configured in Encoder Interface mode provides information on the sensor’s
current position. You can obtain dynamic information (speed, acceleration, deceleration) by
measuring the period between two encoder events using a second timer configured in
capture mode. The output of the encoder which indicates the mechanical zero can be used
for this purpose. Depending on the time between two events, the counter can also be read
at regular times. You can do this by latching the counter value into a third input capture
register if available (then the capture signal must be periodic and can be generated by
another timer). when available, it is also possible to read its value through a DMA request
generated by a real-time clock.
17.3.17 Timer input XOR function
The TI1S bit in the TIMx_CR2 register, allows the input filter of channel 1 to be connected to
the output of a XOR gate, combining the three input pins TIMx_CH1, TIMx_CH2 and
TIMx_CH3.
The XOR output can be used with all the timer input functions such as trigger or input
capture. An example of this feature used to interface Hall sensors is given in
TI1
forward forward backward jitter jitter
up
down up
TI2
Counter
TI1
forward forward backward jitter jitter
up down
TI2
Counter
down