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3.4 Low Speed Signals
3.4.1 External I2C
The I2C bus can be accessed externally using U156 pins. In this case a jumper should be
placed on pin header P16 (HW_I2C) shown in the image below.
Figure 2: External I2C
3.4.2 External HW Control
Also Low Speed Signals are controllable using an external source, this can be done
through control signals pin headers. In this case a jumper should be placed on pin
header P19 (HW_CTRL) shown in the image below.
Figure 3: External Control Signals
The low speed signals circuit shown below shows the connection of these signals to the
microcontroller and QSFP connector.
Figure 4: Low Speed Signals Schematics
When the jumper is inserted on P19, the output signals are tri-stated from the
microcontroller, and hence could be controlled from an external source.
