Quadrature Encoder/Hall-Effect Interface; Zero-Crossing Detection; Zero-Crossing Encoder Interface - Motorola DSP56F803 Hardware User Manual

2.16 Quadrature Encoder/Hall-Effect Interface

The DSP56F803EVM board contains a Quadrature Encoder/Hall-Effect interface
connected to the DSP's Quad Encoder input port. The circuit is designed to accept +3.0V
to +5.0V encoder or Hall-Effect sensor inputs. Input noise filtering is supplied on the input
path for the Quadrature Encoder/Hall-Effect interface, along with additional noise
rejection circuitry inside the DSP.

2.17 Zero-Crossing Detection

An attached UNI-3 motor drive board contains logic that can send out pulses when the
phase voltage of an attached 3-phase motor drops to zero. The motor drive board circuits
generate a 0 to +3.3V DC pulse via voltage comparators. The resulting pulse signals are
sent to a set of jumper blocks shared with the Encoder/Hall-Effect interface. The jumper
blocks allow the selection of Zero-Crossing signals or Quadrature Encoder/Hall-Effect
signals. When in operation, the DSP will only monitor one set of signals, either the
Encoder/Hall-Effect or the Zero-Crossing.
Encoder/Hall circuits.
ZERO_X_A
ZERO_X_B
ZERO_X_C
+5.0V
J2
1
2
3
4
5
6
PIN 1: +5.0V
PIN 2: GROUND
PIN 3: PHASE A
PIN 4: PHASE B
PIN 5: INDEX
PIN 6: HOME
Figure 2-13
FILTER
FILTER
FILTER
FILTER
Figure 2-13. Zero-Crossing Encoder Interface
Technical Summary
shows the encoder interface.
Figure 2-13 shows the Zero-Crossing and
Zero-Crossing Detection
DSP56F803
JG7
1
PHASEA
2
3
4
5 PHASEB
6
7
INDEX
8
9
HOME
2-17