Digilent 410-259P - Manual

P P m m o o d d D D H H B B 1 1 ™ ™
R R e e f f e e r r e e n n c c e e M M a a n n u u a a l l
Revision: February 4, 2013
Note: This document applies to REV A of the board.
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Doc: 502-259 page 1 of 3
Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.
Overview
The PmodDHB1 uses the Texas Instruments
DRV8833 dual H-Bridge motor driver chip to
drive two DC motors or one stepper motor.
Features include:
• Motor voltage can be driven up to
11.8V, with a recommended 10.8V
maximum
• Two H-Bridge interfaces capable of
1.5A RMS (2A Peak)
• 2-channel quadrature encoder
channels for Hall-effect sensors
• Two JST 6-pin connectors for direct
connection to Digilent motor-gearboxes
• Logic input voltage range of 2.5V to 5V
Functional Description
For a detailed description of the Texas
Instruments DRV8833 please refer to the
device data sheet available at TI.com.
The DHB1 is controlled through the Pmod
connector J1. Logical levels on ENx and DIRx
determine the Motor Direction and speed of the
attached motors. The DHB1 uses a
demultiplexer and pull-down resistors on the
inputs to the DRV8833 H-Bridge pins to ensure
that the H-Bridge works in fast decay mode.
The intended operation of the DHB1 uses the
enable pin as the PWM input and the direction
pin as a logic level selector to set the direction
of the motor rotation. Table 1 lists the motor
responses that result from various input
combinations.
The DRV8833 chip provides overcurrent
protection on the motor drive circuits. Each
internal drive FET is independently monitored
for an overcurrent condition and will be shut
down internally to protect the chip. When an
overcurrent condition is sensed the chip will
shut down the FET with the fault and then set
the NFAULT pin low signaling a fault condition
on the chip. The remaining FETs will continue
to operate as normal. When the fault condition
is over, the chip will self-reset and return the
NFAULT logic level to logic high. (See Table 2
for connector descriptions.)
There are two Schmitt trigger buffered inputs
on connectors J2, J3, J7 and J8 that bring
motor speed feedback signals to the controlling
system board. The Digilent motor and gearbox
have hall-effect sensors arranged in a
quadrature encoder format. These buffers
have 5V tolerant inputs, when operated at
3.3V.
DIR1 EN1 Result
0 0 Stop
0 1/PWM Forward
1 0 Stop
1 1/PWM Reverse
DIR2 EN2 Result
0 0 Stop
0 1/PWM Forward
1 0 Stop
1 1/PWM Reverse
Table 1: Motor Control