K60P100M100SF2RM Datasheet, PDF (1051/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

phase B (counting direction)
phase A (counting rate)
FTM counter
increment/decrement
FTM counter
+1 +1 +1 +1 +1 +1 +1 +1 -1 -1 -1 -1 -1
Chapter 39 FlexTimer (FTM)
MOD
CNTIN
0x0000
Time
Figure 39-251. Quadrature Decoder – Count and Direction Encoding Mode
If QUADMODE = 0, then the phase A and phase B encoding mode (see 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:
• 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;
and the FTM counter decrement happens when:
• 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.
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.
1051