User Manual

Connecting TWI Interfaces
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lent, Inc.
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C pin placement on Configuration Type A boards is not uniform; however, every board has the
signals SCL (serial clock) and SDA (serial data). Some boards do not have GND and VCC pins
located with the SCL and SDA signals. In these cases, VCC and GND must be connected elsewhere
on the board.
Pin
Signal
varies SCL
varies SDA
varies
GND
varies
VCC
Type A
Configuration Type B was the first standard for I
2
C pin placement on Digilent microcontroller boards.
Under Configuration Type B, all microcontroller boards have two sets of I
2
C headers with SCL, SDA,
VCC and GND pins located on vertical 2x4 pin headers. This allows devices to be daisy chained.
Pin
Signal
1 or 2 SCL
3 or 4 SDA
5 or 6
VCC
7 or 8
GND
Type B
Configuration Type C is different from Configuration Type B only in that VCC and GND are swapped.
This is the configuration currently used on all Digilent microcontroller boards and Pmods not listed
above and will continue to be on future products.
Pin
Signal
1 or 2 SCL
3 or 4 SDA
5 or 6
GND
7 or 8
VCC
Type C
Connecting a Pmod or microcontroller board of one configuration type with a Pmod or microcontroller
of another type requires slightly different wire connections. The configurations needed for each pairing
are detailed below.