Zero-Crossing Detection; Zero-Crossing Encoder Interface - Motorola DSP56F801 Hardware User Manual

2.15 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 +5.0V 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,
Encoder/Hall-Effect or Zero-Crossing.
Encoder/Hall circuits.
ZERO_X_A
ZERO_X_B
ZERO_X_C
+5.0V
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: N/C
Figure 2-12. Zero-Crossing Encoder Interface
2-18
Figure 2-12
FILTER
FILTER
FILTER
DSP56F801EVM Hardware User's Manual
contains the Zero-Crossing and
JG2
1
2
3
JG9
PFC
1
PWM
4
2
3
5
6
PFC
4
Zero
7
Cross
5
8
6
9
DSP56F801
TD0
TD1
TD2