Datasheet

chipKIT™ Motor Shield™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 4 of 8
There are two Schmitt trigger buffered inputs on connectors J3, J6, J8 and J9 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.
The quadrature encoder signals are a pair of square waves whose frequency is proportional to motor rotation
speed and with the pulses 90° out of phase. You can determine the motor speed with the frequency and motor
rotation direction by the phase relationship between the two signals.
3 Stepper Motor Controller
The stepper motor controller has 4 output signals. It is composed of 4 open-drain transistor amplifiers.
Uno32
Pin #
PIC32
Pin #
Signal Notes
26
60
A: PMD0/RE0
27 61 B: PMD1/RE1
28
62
C: PMD2/RE2
29
63
D: PMD3/RE3
The stepper motor driver can be powered by either VIN, or an external power source connected to J10. If
connecting an external power source, JP5 should be removed to prevent shorting the stepper motor voltages to
the input voltage of the chipKIT board.
4 Servo Motors
The Motor Shield has 4 servo motor connections. They can be powered from VCC5V0 or an external power source
connected to J14. If connecting an external power source, JP6 should be removed. The voltage of the power source
can be measured on analog pin A11 via a resistor divider network (see the schematic for more details).
Uno32
Pin #
PIC32
Pin #
Signal Notes
30
64
Servo1: PMD4/RE4
J16
31
1
Servo2: PMD5/RE5
J17
32
2
Servo3: PMD6/RE6
J18
33
3
Servo4: PMD7/RE7
J20
5 I
2
C Bus and Connectors
The Inter-Integrated Circuit (I
2
C) Interface provides a medium speed (100K or 400K bps) synchronous serial
communications bus. The I
2
C interface provides master and slave operation using either 7 bit or 10 bit device
addressing. Each device is given a unique address, and the protocol provides the ability to address packets to a
specific device or to broadcast packets to all devices on the bus. Refer to the Microchip PIC32MX3XX data sheet
and the PIC32 Family Reference Manual for detailed information on configuring and using the I
2
C interface.