UM10503
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User manual
Rev. 1.3 — 6 July 2012
901 of 1269
NXP Semiconductors
UM10503
Chapter 31: LPC43xx Quadrature Encoder Interface (QEI)
31.6.2.6 QEI Index Count register
This register contains the current value of the encoder position. Increments or decrements
when encoder counts occur, depending on the direction of rotation.
31.6.2.7 QEI Index Compare register 0
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.
31.6.2.8 QEI Timer Reload register
This register contains the reload value of the velocity timer. When the timer (TIME)
reaches zero or the RESV bit is asserted, this value is loaded into the timer (TIME).
31.6.2.9 QEI Timer register
This register contains the current value of the velocity timer. When this timer reaches zero,
the value of velocity register (VEL) is stored in the velocity capture register (CAP), the
timer is reloaded with the value stored in the velocity reload register (LOAD), and the
velocity interrupt (TIM_Int) is asserted.
31.6.2.10 QEI Velocity register
This register contains the running count of velocity pulses for the current time period.
When the velocity timer (TIME) reaches zero, the content of this register is captured in the
velocity capture register (CAP). After capture, this register is set to zero. This register is
also reset when the velocity reset bit (RESV) is asserted.
Table 733. QEI Index Count register (INXCNT- address 0x400C 6020) bit description
Bit
Symbol
Description
Reset value
31:0
ENCPOS
Current encoder position value.
0
Table 734. QEI Index Compare register 0 (INXCMP0 - address 0x400C 6024) bit description
Bit
Symbol
Description
Reset value
31:0
ICMP0
Index compare value.
0xFFFF FFFF
Table 735. QEI Timer Load register (LOAD - address 0x400C 6028) bit description
Bit
Symbol
Description
Reset value
31:0
VELLOAD
Current velocity timer pre-load value.The velocity
timer counts down from this value.
0xFFFF FFFF
Table 736. QEI Timer register (TIME - address 0x400C 602C) bit description
Bit
Symbol
Description
Reset value
31:0
VELVAL
Current velocity timer value.
0xFFFF FFFF
Table 737. QEI Velocity register (VEL - address 0x400C 6030) bit description
Bit
Symbol
Description
Reset value
31:0
VELPC
Current velocity pulse count.
0x0