Digilent 410-185P-KIT - Manual (Page 6)

Cerebot MC7 Reference Manual
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The voltage monitoring can be
enabled/disabled via jumpers JP9-JP12.
The current/voltage monitoring signals are
connected to the A/D converter inputs in the
following way:
IMON1 AN0
IMON2 AN1
IMON3 AN2
IMON4 AN3
VMON1
AN10
VMON2 AN11
VMON3 AN12
VMON4 AN13
Over-current Detection
The Cerebot MC7 provides an over-current
monitoring mechanism for detecting excessive
current flow through any of the half bridge
circuits.
Four comparators are used to monitor the
current measurement from each half bridge
compared to a fixed reference voltage. The
outputs of these comparators are OR’d
together and applied to external interrupt INT1
on the dsPIC microcontroller.
A fixed reference voltage of 2.33V is used to
set the comparator threshold for determining
an over current condition. This sets the
comparator to signal an over-current condition
at 6A. If the current through any half bridge
exceeds ~6A, an interrupt can be triggered on
INT1.
CAN Interface
The Controller Area Network (CAN) standard is
a control networking standard originally
developed for use in automobile systems, but
has since become a standard used in various
industrial control and building automation
networking applications as well.
The dsPIC33 microcontroller used on the
Cerebot MC7 contains a CAN network
controller. This CAN controller in combination
with a Microchip MCP2551 CAN transceiver
allow the Cerebot MC7 board to operate on a
CAN network. Refer to the
dsPIC33FJXXXMCX06A/X08A/X10A Data
Sheet and the dsPIC33F Family Reference
Manual, plus CAN network documentation for
information on operation of the CAN controllers
and CAN networking in general.
There is no standard connector for use with
CAN networks. The Cerebot MC7 board
provides a 2x6 pin header connector, J9, for
access to the CAN signals. Refer to the
schematic for the Cerebot MC7 board for
information on the connectors and signals.
Digilent 6-pin or 2x6 to dual 6-pin cables can
be used to daisy chain Digilent boards together
in a CAN network. A Digilent 6-Pin cable in
combination with a Digilent PmodCON1 Screw
Terminal Connector module can be used to
connect the Cerebot MC7 board to other
network wiring configurations.
The CAN network standard requires that the
network nodes at each end of a network
provide 120 ohm termination. The Cerebot
MC7 provides the termination resistor and
jumpers to enable/disable this resistor
depending on the location of the board in the
network. Jumper JP6 is used to enable/disable
the termination resistor. Install a shorting block
on the jumper pins to enable the termination
resistor, or remove the shorting block to
disable the termination resistor.
RC Servo Connectors
The Cerebot MC7 provides eight 3-pin RC
hobby servo connectors for direct control of
servos in robotics and embedded hardware
actuator applications. These connectors are
on the upper right side of the board.
The servo connectors S1-S8 are connected to
PORTD bits 0-7 in the dsPIC33F
microcontroller. These signals also appear on
Pmod connector JC, and PORTD bits 4-7 are
also used by the on-board LEDs. Devices
connected to Pmod connector JC may interfere
with operation of servos on the servo