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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
467 of 571
NXP Semiconductors
UM10316
Chapter 27: LPC29xx Quadrature Encoder Interface (QEI)
6.3.6 QEI Index Count (INXCNT)
This register contains the current value of the encoder position. Increments or decrements
when encoder counts occur, depending on the direction of rotation.
6.3.7 QEI Index Compare (INXCMP)
This register contains an index compare value. This value is compared against the current
value of the index count register. Interrupts can be enabled to interrupt when the compare
value is less than, equal to, or greater than the current value of the index count register.
6.3.8 QEI Timer Reload (QEILOAD)
This register contains the reload value of the velocity timer. When the timer (QEITIME)
overflows or the RESV bit is asserted, this value is loaded into the timer (QEITIME).
6.3.9 QEI Timer (QEITIME)
This register contains the current value of the velocity timer. When this timer overflows the
value of velocity counter (QEIVEL) is stored in the velocity capture register (QEICAP), the
velocity counter is reset to zero, the timer is reloaded with the value stored in the velocity
reload register (QEILOAD), and the velocity interrupt (TIM_Int) is asserted.
6.3.10 QEI Velocity (QEIVEL)
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.
Table 394: QEI Position Compare Register 2 (CMPOS2 - 0xE00C 901C)
Bit
Symbol
Description
Reset
value
0:31
-
Current position value.
0
Table 395: QEI Index Count Register (CMPOS - 0xE00C 9020)
Bit
Symbol
Description
Reset
value
0:31
-
Current position value.
0
Table 396: QEI Index Compare Register (CMPOS - 0xE00C 9024)
Bit
Symbol
Description
Reset
value
0:31
-
Current position value.
0
Table 397: QEI Timer Load Register (QEILOAD - 0xE00C 9028)
Bit
Symbol
Description
Reset
value
0:31
-
Current velocity timer load value.
0
Table 398: QEI Timer Register (QEITIME - 0xE00C 902C)
Bit
Symbol
Description
Reset
value
0:31
-
Current velocity timer value.
0