Digilent 410-262P User Manual

chipKIT™ Motor Shield

Reference Manual

Revision: April 16, 2013
Note: This document applies to REV D of the board.

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Overview

The chipKIT™ Motor Shield is an expansion
board for use with the chipKIT Uno32 and
chipKIT uC32. It provides additional circuitry
and connectors for the Uno32 and uC32 to
drive various motors types.

The chipKIT Motor Shield is designed to drive
DC motors, servo motors, and stepper motors.
It also provides additional I/O via an I2C I/O
extender.

Features include:

 2 DC motor driver channels,

accessible with either a JST 6-pin
connector or a terminal block

 2 DC motor encoder input signals for

each DC motor channel

 4 servo motor channels
 I2C General purpose I/O expander

with 4 LEDs 2 push buttons and 2
user settable jumpers

 1 4-wire unipolar stepper motor

channel

 Standard chipKIT Shield connectors

Functional Description

The chipKIT Motor Shield is designed to be used with the chipKIT Uno32 or chipKIT uC32 board.
When used with these boards, the microcontroller and shield provide the necessary supporting
hardware and connectors to control most types of small motors. The rest of this document will only
reference the Uno32; however, the shield can also be used with the chipKIT uC32.

The chipKIT Motor Shield has the following connectors:

J1: Power Supply for the DC motor driver

This connector provides power to the DVR8833RTY motor driver for the DC motors. Motor supply
voltage range is 2.7-10.8 V.

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chipKIT Motor Shield Reference Manual

J3 & J6: DC motor 6-pin JST connector

These connections provide power and feedback signals for DC motors. The pin-outs are compatible
with the Digilent DC gear-motors.

J5 & J7: DC motor terminal block connector

These connections provide the power supply pin-out for most two wire DC motors.

J2: DC motor driver disable

Shorting these two pins (or driving the NS signal pin low) will put the DC motor driver into sleep mode.
This disables the motor driver and therefore reduces power consumption. This option is useful for low
power applications.

J4: DC motor driver fault indicator

The NF signal will be driven low when there is a fault detected within the DC motor driver. Possible
reasons for fault include overcurrent, overheat, and low voltage.

J8 & J9: DC motor feedback signal headers

Headers for connecting DC motor feedback signals.

J10: Power Supply for Stepper motor

This connector provides power for driving the stepper motor.

J12 & J13: Stepper motor terminal block connectors

These connections are used for driving a stepper motor.

J14: Power Supply for servo motors

This connector provides external power for driving the servo motors. If using this header remove JP6
to ensure that servo power supply is not shorted to the 5 Volt Uno32 power supply.

J11 & J15: Digital Signal Pass-Through Connectors

This connector passes the digital I/O pins on the Uno32 through to the chipKIT Motor Shield.

J21: I2C #1 Daisy Chain Connector

This is a 2x4 pin header connector that provides access to the I2C signals SDA and SCL as well as
power from the 3.3V power bus and ground. This can be used to extend the I2C bus off of the board
and to power external I2C devices. Digilent has cables and a selection of I2C peripheral modules that
can be accessed using this connector.

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chipKIT Motor Shield Reference Manual

Uno32

Pin #

PIC32

Pin #

Signal

Notes

3

46

Enable1: OC1/RD0

4 59

Direction1: RF1

3/5

46/49

Enable2: OC1/RD0 or OC2/RD1

Select with JP1

4/34

59/53

Direction2: RF1 or PMRD/CN14/RD5

Select with JP2

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

J19: Analog Signal Pass-Through Connector

This connector passes the analog input pins on the Uno32 through the chipKIT Motor Shield.

J22: Power Pass-Through Connector

This connector passes the power connector from the Uno32 through the chipKIT Motor Shield, and
powers the chipKIT Motor Shield from the Uno32.

DC Motor Controller

The Motor Shield provides a means to control 2 independent DC motors via a DRV883 dual H-bridge
motor driver. The motor driver must be powered via J1 to operate, voltages between 2.7 and 10.8
volts are acceptable. Each channel is controlled by an “enable” and “direction” signal.

Channel 2 can be set up for identical or independent operation from channel 1 using JP1 and JP2.
PWM levels on enable pins will regulate the speed of the motors. Logic levels on direction pins will

determine the motors rotation direction of the attached DC motors. The chipKIT Uno32 uses a
demultiplexer and pull-down resistors on the inputs to the DRV8833 H-Bridge pins to ensure that the
H-Bridge only works in fast decay mode. 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.)

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Table 1: Motor Control