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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
466 of 571
NXP Semiconductors
UM10316
Chapter 27: LPC29xx Quadrature Encoder Interface (QEI)
6.3 Position, index and timer registers
6.3.1 QEI Position (QEIPOS)
This register contains the current value of the encoder position. Increments or decrements
when encoder counts occur, depending on the direction of rotation.
6.3.2 QEI Maximum Position (QEIMAXPOS)
This register contains the maximum value of the encoder position. In forward rotation the
position register resets to zero when the position register exceeds this value. In reverse
rotation the position register resets to this value when the position register decrements
from zero.
6.3.3 QEI Position Compare 0 (CMPOS0)
This register contains a position compare value. This value is compared against the
current value of the position register. Interrupts can be enabled to interrupt when the
compare value is less than, equal to, or greater than the current value of the position
register.
6.3.4 QEI Position Compare 1 (CMPOS1)
This register contains a position compare value. This value is compared against the
current value of the position register. Interrupts can be enabled to interrupt when the
compare value is less than, equal to, or greater than the current value of the position
register.
6.3.5 QEI Position Compare 2 (CMPOS2)
This register contains a position compare value. This value is compared against the
current value of the position register. Interrupts can be enabled to interrupt when the
compare value is less than, equal to, or greater than the current value of the position
register.
Table 390: QEI Position Register (QEIPOS - 0xE00C 900C)
Bit
Symbol
Description
Reset
value
0:31
-
Current position value.
0
Table 391: QEI Maximum Position Register (QEIMAXPOS - 0xE00C 9010)
Bit
Symbol
Description
Reset
value
0:31
-
Current maximum position value.
0
Table 392: QEI Position Compare Register 0 (CMPOS0 - 0xE00C 9014)
Bit
Symbol
Description
Reset
value
0:31
-
Current position value.
0
Table 393: QEI Position Compare Register 1 (CMPOS1 - 0xE00C 9018)
Bit
Symbol
Description
Reset
value
0:31
-
Current position value.
0