AT32UC3C1512C Automotive Atmel Corporation, AT32UC3C1512C Automotive Datasheet - Page 1050

• Manufacturer Part Number: AT32UC3C1512C Automotive
• Manufacturer: Atmel Corporation

34.6.1.4
34.6.1.5
34.6.1.6
34.6.1.7
Figure 34-5. Quadrature Clock and Direction Decoding (TOP.PCTOP = 4)
9166C–AVR-08/11
Position counter
Index detection
Revolution counter
Waveforms
CNTDIR
QPulse
QEPA
QEPB
The 16-bit position counter is incremented or decremented on every count pulse, generated by
the quadrature decoder module. The counting direction is displayed in SR.CNTDIR.
If the position counter reaches the TOP.PCTOP value when counting up or the 0 value when
counting down, the counter wraps around. The Position Counter Roll Over (PCRO) interrupt is
generated.
Usually, the TOP.PCTOP value should always be set to the total number of quadrature states
minus one, which is (quadrature_encoder_lines_count *4) -1.
The optional index signal QEPI may be used to correct the position counter if quadrature states
have been missed due to noise. If the Index Enable bit (CF.IDXE) is written to one, detection of
the QEPI signal will reset the position counter to 0 on a selected phase of quadrature signals.
This selected phase is configured via the Detection Phase field (CF.IDXPHS).
The Index Error (IDXERR) interrupt is triggered if the index detection occurs and the position
counter value is not 0.
The revolution counter is incremented/decremented each time the position counter rolls over. It
rolls over when it reaches the TOP.RCTOP value.
PC
RC
0
1
0
2
3
4
0
1
1
2
1
0
4
3
0
2
1
AT32UC3C
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