OM13001,598 NXP Semiconductors, OM13001,598 Datasheet - Page 58

• Manufacturer Part Number: OM13001,598
• Description: EA LPC177X/8X EVAL BOARD
• Manufacturer: NXP Semiconductors
• Series: -r
• Type: MCUr

Specifications of OM13001,598

• Contents: Board, Cable, Headphones, Registration Card
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: LPC1788
• Other names: 568-6707

NXP Semiconductors
LPC178X_7X
Objective data sheet
7.28.1 Features
7.28 Quadrature Encoder Interface (QEI)
7.29 ARM Cortex-M3 system tick timer
PWM to immediately release all motor drive outputs. At the same time, the motor control
PWM is highly configurable for other generalized timing, counting, capture, and compare
applications.
The maximum PWM speed is determined by the PWM resolution (n) and the operating
frequency f: PWM speed = f/2
Table 8.
Remark: The QEI is available on parts LPC1788/87/86 and LPC1778/77/76
A quadrature encoder, also known as a 2-channel incremental encoder, converts angular
displacement into two pulse signals. By monitoring both the number of pulses and the
relative phase of the two signals, the user can track the position, direction of rotation, and
velocity. In addition, a third channel, or index signal, can be used to reset the position
counter. The quadrature encoder interface decodes the digital pulses from a quadrature
encoder wheel to integrate position over time and determine direction of rotation. In
addition, the QEI can capture the velocity of the encoder wheel.
The ARM Cortex-M3 includes a system tick timer (SYSTICK) that is intended to generate
a dedicated SYSTICK exception at a 10 ms interval. In the LPC178x/7x, this timer can be
clocked from the internal AHB clock or from a device pin.
PWM resolution
6 bit
8 bit
10 bit
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Tracks encoder position.
Increments/decrements depending on direction.
Programmable for 2 or 4 position counting.
Velocity capture using built-in timer.
Velocity compare function with “less than” interrupt.
Uses 32-bit registers for position and velocity.
Three position compare registers with interrupts.
Index counter for revolution counting.
Index compare register with interrupts.
Can combine index and position interrupts to produce an interrupt for whole and
partial revolution displacement.
Digital filter with programmable delays for encoder input signals.
Can accept decoded signal inputs (clk and direction).
Connected to APB.
PWM speed at operating frequency 120 MHz
All information provided in this document is subject to legal disclaimers.
Rev. 2 — 27 May 2011
n
(see
Table
8).
PWM speed
1.875 MHz
0.468 MHz
0.117 MHz
32-bit ARM Cortex-M3 microcontroller
LPC178x/7x
© NXP B.V. 2011. All rights reserved.
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