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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
468 of 571
NXP Semiconductors
UM10316
Chapter 27: LPC29xx Quadrature Encoder Interface (QEI)
6.3.11 QEI Velocity Capture (QEICAP)
This register contains the most recently measured velocity of the encoder. This
corresponds to the number of velocity pulses counted in the previous velocity timer
period.The current velocity count is latched into this register when the velocity timer
overflows.
6.3.12 QEI Velocity Compare (VELCOMP)
This register contains a velocity compare value. This value is compared against the
captured velocity in the velocity capture register. If the capture velocity is less than the
value in this compare register, a velocity compare interrupt (VELC_Int) will be asserted, if
enabled.
6.3.13 QEI Digital Filter (FILTER)
This register contains the sampling count for the digital filter. A sampling count of zero
bypasses the filter.
6.4 Interrupt registers
6.4.1 QEI Interrupt Status (QEIINTSTAT)
This register provides the status of the encoder interface and the current set of interrupt
sources that are asserted to the controller. Bits set to 1 indicate the latched events that
have occurred; a zero bit indicates that the event in question has not occurred. Writing a 0
to a bit position clears the corresponding interrupt.
Table 399: QEI Velocity Register (QEIVEL - 0xE00C 9030)
Bit
Symbol
Description
Reset
value
0:31
-
Current velocity pulse count.
0
Table 400: QEI Velocity Capture Register (QEICAP - 0xE00C 9034)
Bit
Symbol
Description
Reset
value
0:31
-
Current velocity pulse count.
0
Table 401: QEI Velocity Compare Register (VELCOMP - 0xE00C 9038)
Bit
Symbol
Description
Reset
value
0:31
-
Current velocity pulse count.
0
Table 402: QEI Digital Filter Register (FILTER - 0xE00C 903C)
Bit
Symbol
Description
Reset
value
0:31
-
Digital filter sampling delay
0x0