Datasheet

chipKIT™ Pro MX7 Board Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 18 of 35
The pull-ups on I2C1 on the chipKIT Pro MX7 board are actually implemented using current mirrors rather than
simple resistors. These current mirrors source approximately 1.7mA. The use of current mirrors provides faster rise
times on the I
2
C signals and provides the ability to drive longer cable runs reliably than would be the case with
simple pull-up resistors.
Pull-ups
Enabled
Pull-ups
Disabled
SCL
SDA
3V3
GND
SCL
SDA
3V3
GND
When using the chipKIT Pro MX7 with the MPIDE and the chipKIT system, the I
2
C interfaces are accessed using the
standard chipKIT Wire library, or the Digilent DTWI library.
The Wire library supports a single I
2
C interface, I2C2 on J8. This is accessed using the Wire object.
The DTWI library supports four I
2
C interfaces. The DTWI0 object class is used to create an object for access to I2C1,
connector J7, and the DTWI1 object class is used to access I2C2, connector J8. The DTWI2 object class is used to
access I2C3, Pmod connector JE, and the DTWI3 object class is used to access I2C5, Pmod connector JF.
The pinouts of the I
2
C connectors are as follows:
Connector J7 – I2C1
 J7-1, J7-2 – SCL1
 J7-3, J7-4 – SDA1
 J7-5, J7-6 – GND
 J7-7, J7-8 – VCC3V3
Connector J8 – I2C2
 J8-1, J8-2 – SCL2
 J8-3, J8-4 – SDA2
 J8-5, J8-6 – GND
 J8-7, J8-8 – VCC3V3
Pmod connector JE – I2C3
 JE-02 – SCL3
 JE-03 – SDA3
Pmod connector JF – I2C5
Jumper Settings for I
2
C Pull-Up Resistor