mcf51jf128 Freescale Semiconductor, Inc, mcf51jf128 Datasheet - Page 897

• Manufacturer Part Number: mcf51jf128
• Description: Mcf51jf128 Reference Manual
• Manufacturer: Freescale Semiconductor, Inc

37.4.23.1 Quadrature Decoder Boundary Conditions
The following two figures illustrate examples of motor jittering that cause FTM counter
transitions. Motor position control applications are expected to observe these behaviors.
The following figure shows motor jittering produced by the phase B and A pulses,
respectively. The first highlighted transition causes a jitter on the FTM counter value near
the maximum count value (MODH:L). The second indicated transition occurs on phase A
and causes the FTM counter transition between the maximum and minimum count
values, which are defined by the MODH:L and CNTINH:L registers.
Freescale Semiconductor, Inc.
Figure 37-220. FTM Counter Overflow in Down Counting for Quadrature Decoder Mode
FTM counter
CNTINH:L
MODH:L
0x0000
phase A
phase B
increment/decrement
Figure 37-221. Motor Position Jittering in a Mid Count Value
FTM counter
FTM counter
CNTINH:L
phase A
phase B
MODH:L
0x0000
MCF51JF128 Reference Manual, Rev. 2, 03/2011
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
set TOF
clear TOFDIR
Preliminary
set TOF
clear TOFDIR
Chapter 37 FlexTimer (FTM)
Time
Time
897