UM10503
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User manual
Rev. 1.3 — 6 July 2012
900 of 1269
NXP Semiconductors
UM10503
Chapter 31: LPC43xx Quadrature Encoder Interface (QEI)
31.6.2 Position, index and timer registers
31.6.2.1 QEI Position register
This register contains the current value of the encoder position. Increments or decrements
when encoder counts occur, depending on the direction of rotation.
31.6.2.2 QEI Maximum Position register
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.
31.6.2.3 QEI Position Compare register 0
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.
31.6.2.4 QEI Position Compare register 1
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.
31.6.2.5 QEI Position Compare register 2
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 728. QEI Position register (POS - address 0x400C 600C) bit description
Bit
Symbol
Description
Reset value
31:0
POS
Current position value.
0
Table 729. QEI Maximum Position register (MAXPOS - address 0x400C 6010) bit description
Bit
Symbol
Description
Reset value
31:0
MAXPOS
Maximum position value.
0
Table 730. QEI Position Compare register 0 (CMPOS0 - address 0x400C 6014) bit description
Bit
Symbol
Description
Reset value
31:0
PCMP0
Position compare value 0.
0xFFFF FFFF
Table 731. QEI Position Compare register 1 (CMPOS1 - address 0x400C 6018) bit description
Bit
Symbol
Description
Reset value
31:0
PCMP1
Position compare value 1.
0xFFFF FFFF
Table 732. QEI Position Compare register 2 (CMPOS2 - address 0x400C 601C) bit description
Bit
Symbol
Description
Reset value
31:0
PCMP2
Position compare value 2.
0xFFFF FFFF