Industrial Shields Raspberry PLC 19R+, Quick User Manual

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Rev. 8: 29-04-2021
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SPI0 – MISO/MOSI/SCK
These pins can only work as a 3.3V pins if the RS-485 protocol is not going to be used. As the
RS-485 protocol uses the SPI to communicate with the Raspberry board, both behaviours
cannot happen at the same time as the RS-485 would not work.
These pins are not established with a pull-up or a pull-down configuration by default. The
Raspberry board allows the pins to be set either in a pull-up or pull-down configuration.
Otherwise, an external pull-up or pull-down circuit could be set.
GPIO25
GPIO25 is a Raspberry PI 4 GPIO pin that can be set as an input or output. It does not have any
default function, so it can be configured without any restrictions. The pin is powered at 3.3
volts; a higher voltage might be dangerous for the device.
This pin is not established with a pull-up or a pull-down configuration by default. If the pin has
to be used, it might require a pull-up or pull-down configuration for prevention. The Raspberry
Pi 4 allows the pin to be set in both configurations; however, it can be set an external pull-up
or pull-down circuit in order to correctly work with this pin.