Boreas Technologies BOS1901-KIT-B02 User Manual page 27

BOS1901-KIT
User Guide
By default, the GPIOs are in the microcontroller 3.3 V supply domain. To use these GPIOs with a system
operating in another voltage domain requires modification of the BOS1901-KIT PCB configuration.
When SB5 is unpopulated, GPIOs supply voltage is provided by VIO and GND of the J3 connector. This
J3 header connector is provided in the box but is not initially populated. Refer to the board schematics
in section 10.1 for MCU pins numbers corresponding to IO0, IO1, IO2 and IO3.
9.2.4 External SPI
The BOS1901 features an SPI communication interface. By default, each BOS1901 are connected to the
MCU SPI master. It is possible to bypass the MCU and use an external SPI master without breaking the
board. This can be useful when trying to connect a BOS1901 directly to an external system.
To use an external SPI, it is mandatory to enable it using the COMM Select switch on the board by
setting it to EXT position. USB port must still be connected since it supplies the digital switches.
By default, the SPIs are in the microcontroller 3.3 V supply domain. To use these SPIs with a system
operating in another voltage domain requires modification of the BOS1901-KIT PCB configuration.
When SB4 is unpopulated, SPI supply voltage is provided by VDDIO and GND of the external SPI header
connectors. The external SPI header connectors are provided in the box but is not initially populated.
BT001DDK04.01 – Issue 1
Table 12: GPIOs supply voltage solder bridge configuration
GPIOs Supply Source
+3.3V (MCU supply)
VIO (3.3 V to 5.5 V)
Figure 22: Comm selection switch and SPI header location
Table 13: SPIs supply voltage solder bridge configuration
SPI Supply Source
+3.3V (MCU supply)
VDDIO (1.62 V to 5.5 V)
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SB5 State
Populated
Unpopulated
SB4 State
Populated
Unpopulated
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