Dragino PAB2, Руководство пользователя

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The USB Host of Yun Shield gets power from the Arduino +5v pin, since the +5v from Arduino
comes from the +5V LDO, to avoid overheated on the Arduino Board, when the USB host is in
used, it is recommended to use +7v DC .
Interface:
The RJ45, WiFi, USB Host and Failsafe are connected to the Dragino HE module directly. And the
Dragino HE module use SPI and UART to communicate with Arduino Board. Yun Shield is
compatible with 3.3v and 5v Arduino board. The on board jumper SV1 is used to set the SPI and
UART to 3.3v or 5v level.
The SPI interface is used to upload the sketches comes from the Arduino IDE. SPI interface only
connects to Dragino HE during uploading so the Arduino SPI can still be used to connect to other
SPI slave devices.
The UART interface is used for the Bridge class in Arduino, there are lots of examples explain how
to use the bridge class in the Arduino IDE. It is the core of Yun solution. We must make sure the
serial Interface of Arduino is not used by other hardware.
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