Digilent 410-185P-KIT - Manual (Page 8)

Cerebot MC7 Reference Manual
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broadcast packets to all devices on the bus.
Refer to the data sheet for the dsPIC
microcontroller and the dsPIC33F Family
Reference Manual for detailed information on
configuring and using the I
2 C interface.
The dsPIC33F microcontroller provides two
independent I
2 C interfaces. There are two sets
of connectors in the lower left corner of the
board for access to the two I
2 C ports.
Connector J6 provides access to I 2 C port #1
while connector J8 provides access to I 2 C port
#2.
Each I
2 C connector provides two positions for
connecting to the I2C signals, ground and the
3.3V power supply. By using two-wire or four-
wire MTE cables (available separately from
Digilent) a daisy chain of multiple Cerebot MC7
boards or other I
2 C-capable boards can be
created.
The I
2 C bus is an open-collector bus. Devices
on the bus actively drive the signals low. The
high state on the I
2 C signals is achieved by
pull-up resistors when no device is driving the
lines low. One device on the I
2 C bus must
provide the pull-up resistors. I
2
C bus #2 has
permanently connected pull-up resistors. I 2 C
bus #1 has selectable pull-up resistors that can
be enabled or disabled via jumper blocks on J5
and J7. The pull-ups are enabled by installing
shorting blocks and are disabled by removing
the shorting blocks. The shorting blocks are
placed so that they line up with the SCL and
SDA labels on the board. Only one device on
the bus should have the pull-ups enabled.
S
C
L
S
D
A
S
C
L
S
D
A
Pull-ups
Enabled Pull-ups
Disabled
3
V
3
G
N
D
3
V
3
G
N
D
Jumper Settings for I2C Pull-Up Resistors
I
2
C EEPROM
The Cerebot MC7 provides one on-board I
2 C
device, a Microchip 24LC256 serial EEPROM.
This device is connected to I2C bus #2. The
24LC256 is a 256Kbit (32Kbyte) serial
EEPROM device to provide non-volatile
memory storage. The device address for the
24LC256 is 1010000 (0x50).
Refer to the Microchip data sheet for detailed
information on the operation of this device.
Pmod Connectors
The Cerebot MC7 has three Pmod connectors
for connecting Digilent Pmod peripheral
modules. Digilent Pmods are a line of small
peripheral modules that provide various kind of
I/O interfaces. The Pmod line includes such
things as button, switch and LED modules,
connector modules, LCD displays, high current
output drivers, and many others.
There are two styles of Pmod connector: six-
pin and twelve-pin. Both connectors use
standard pin headers with 100mil spaced pins.
The six-pin connectors have the pins in a 1x6
configuration, while the twelve-pin connectors
use a 2x6 configuration. The six-pin
connectors provide four I/O signals, ground
and a switchable power connection. The
twelve-pin connectors provide eight I/O
signals, two power and two ground pins. The
twelve-pin connectors have the signals
arranged so that one twelve-pin connector is
equivalent to two of the six-pin connectors.
The power connection is switchable between
the regulated 3.3V main board supply and the
unregulated input supply.
On the Cerebot MC7, Pmod connector JA is a
six pin connector that can be used for general
purpose I/O or for connection to UART1 or
SPI1. Connector JB is a twelve pin connector
that can be used for general I/O and provides
access to SPI2, and two external interrupts
(INT2 and INT3). Connector JC is a twelve pin
connector that can be used for general I/O,