Digilent MX7cK - Manual (Page 15)

Cerebot MX7cK Reference Manual
www.digilentinc.com page 15 of 36
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interface pins, the following statement must
appear in the main program module:
#pragma config FCANIO=OFF
The chipKIT MPIDE boot loader sets the
configuration variables, and so no action is
necessary when using the MPIDE software
system.
The pins on the PIC32MX795 microcontroller
used by signals for the CAN1 controller to
connect to its transceiver are shared with two
of the signals for the UART2 and SPI4 ports.
Jumpers JP1 and JP2 are used to select the
use of these two signals. Place JP1 and JP2 in
the CAN position for use of the CAN1 network
interface. Place JP1 and JP2 in the PMOD
position for use of these signals for UART or
SPI operation. These signals connect to pins 1
& 4 of Pmod connector JF. When JP1 and JP2
are in the CAN position, Pins 1 & 4 of Pmod
connector JF are not useable. In some cases it
may be possible to use UART2 at the same
time as CAN1 as the RX and TX pins are not
used by the CAN interface (only RTS and CTS
are used). When JP1 and JP2 are in the CAN
position Pmod pins JF-01 and JF-04 are not
connected to the PIC32 microcontroller.
There is no standard connector for use with
CAN networks. The Cerebot MX7cK board
provides two 2x6 pin header connectors for
access to the CAN signals. Connector J9
provides access to the signals for the CAN1
network controller, and connector J10 provides
access to the signals for CAN2. Refer to the
Cerebot MX7cK schematic, Sheet 6, for
information on the connectors and signal
assignments. 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
MX7cK 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
MX7cK provides termination resistors and
jumpers to enable/disable them depending on
the location of the board in the network.
Jumper JP5 is used to enable/disable the
termination resistor for the CAN1 network
connector, and JP7 is used to enable/disable
the termination resistor for CAN2. Install a
shorting block on the jumper pins to enable the
termination resistor, or remove the shorting
block to disable it.
UART Interface
The PIC32MX795 microcontroller can provide
up to six UARTs. Due to conflicting uses of
many of the pins used by the UARTs, the
Cerebot MX7cK is designed to allow use of two
of them: UART1 and UART2. The UARTs can
provide either a 2-wire or a 4-wire
asynchronous serial interface. The 2-wire
interface provides receive (RX) and transmit
(TX) pins. The 4-wire interface includes
request-to-send (RTS) and clear-to-send
(CTS) in addition to receive and transmit.
UART1 can be accessed from Pmod connector
JE and UART2 can be accessed from Pmod
connector JF using the following pins:

U1CTS JE-01

U1TX JE-02

U1RX JE-03

U1RTS JE-04

U2CTS JF-01

U2TX JF-02

U2RX JF-03

U2RTS JF-04
Note that early versions of the Microchip
PIC32MX5XX/6XX/7XX Family Data Sheet
refer to UART1 as UART1A and UART2 as
UART3A.
Detailed information about the operation of the
UART peripherals can be found in the PIC32
Family Reference Manual, Section 21, UART.
The USB Serial converter is connected to
UART1. The MPIDE uses this to communicate