mcf51jf128 Freescale Semiconductor, Inc, mcf51jf128 Datasheet - Page 895

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

The QUADMODE selects the encoding mode used in the quadrature decoder mode. If
QUADMODE = 1, then the count and direction encoding mode (refer to the following
figure) is enabled. In this mode, the phase B input value indicates the counting direction
(FTM counter increment or decrement), and the phase A input defines the counting rate
(FTM counter is updated when there is a rising edge at phase A input signal).
If QUADMODE = 0, then the phase A and phase B encoding mode (refer to the
following figure) is enabled. In this mode, the relationship between phase A and B
signals indicates the counting direction, and phase A and B signals define the counting
rate (FTM counter is updated when there is an edge either at the phase A or phase B
signals).
If PHAPOL = 0 and PHBPOL = 0, then the FTM counter increment happens when:
and the FTM counter decrement happens when:
Freescale Semiconductor, Inc.
• there is a rising edge at phase A signal and phase B signal is at logic zero;
• there is a rising edge at phase B signal and phase A signal is at logic one;
• there is a falling edge at phase B signal and phase A signal is at logic zero;
• there is a falling edge at phase A signal and phase B signal is at logic one;
• there is a falling edge at phase A signal and phase B signal is at logic zero;
• there is a falling edge at phase B signal and phase A signal is at logic one;
• there is a rising edge at phase B signal and phase A signal is at logic zero;
• there is a rising edge at phase A signal and phase B signal is at logic one.
Figure 37-217. Quadrature Decoder – Count and Direction Encoding Mode
phase B (counting direction)
phase A (counting rate)
MCF51JF128 Reference Manual, Rev. 2, 03/2011
increment/decrement
FTM counter
FTM counter
CNTINH:L
MODH:L
0x0000
Preliminary
1 1 1 1 1 1 1 1 1 1 1 1 1 -
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Time
Chapter 37 FlexTimer (FTM)
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