UM10360 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
User manual Rev. 3 — 19 December 2013 554 of 841
NXP Semiconductors
UM10360
Chapter 26: LPC176x/5x Quadrature Encoder Interface (QEI)
26.6.3.10 QEI Velocity register (QEIVEL - 0x400B C030)
This register contains the running count of velocity pulses for the current time period.
When the velocity timer (QEITIME) overflows the contents of this register is captured in
the velocity capture register (QEICAP). After capture, this register is set to zero. This
register is also reset when the velocity reset bit (RESV) is asserted.
26.6.3.11 QEI Velocity Capture register (QEICAP - 0x400B C034)
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.
26.6.3.12 QEI Velocity Compare register (VELCOMP - 0x400B C038)
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.
26.6.3.13 QEI Digital Filter register (FILTER - 0x400B C03C)
This register contains the sampling count for the digital filter. A sampling count of zero
bypasses the filter.
Table 495: QEI Timer register (QEITIME - address 0x400B C02C) bit description
Bit Symbol Description Reset
value
31:0 - Current velocity timer value. 0
Table 496: QEI Velocity register (QEIVEL - address 0x400B C030) bit description
Bit Symbol Description Reset
value
31:0 - Current velocity pulse count. 0
Table 497: QEI Velocity Capture register (QEICAP - address 0x400B C034) bit description
Bit Symbol Description Reset
value
31:0 - Captured velocity pulse count. 0
Table 498: QEI Velocity Compare register (VELCOMP - address 0x400B C038) bit description
Bit Symbol Description Reset
value
31:0 - Velocity compare value. 0
Table 499: QEI Digital Filter register (FILTER - address 0x400B C03C) bit description
Bit Symbol Description Reset
value
31:0 - Digital filter sampling delay 0x0
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