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Raspberry PI - SPI HAT (w/Dual SPI bus and voltage) - will it work ok?
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pickleit:
Hi

I would like the communities comments on whether or not the my design for a raspberry pi SPI breakout HAT; actually works.

The board has the following  features:

1) Both SPI buses are broken out to 8 way 0.1in pitch dupont unshrouded headers.
2) each SPI bus has a switch to switch the working voltage between 3.3V and 1.8.

How it should work:

If the switch is set to 3.3V, the MOSI, MISO, SCLK, CS pins go to a "Quad SPDT Analog Switch" then direct to the 8-way header.

If the switch is set to 3.3V, the MOSI, MISO, SCLK, CS pins go to a "Quad SPDT Analog Switch" then to a "Bidirectional Voltage-level Translator", then on to the 8-way header. Also the 3.3V from GPIO pins goes to a Voltage regulator.

Also, for protection, there are 100nf caps across the 3.3v & GND and 150 ohm resistors on each of the  MOSI, MISO, SCLK, CS pins.

Please let me know if there is anything I could do better; and more importantly, does my design work?

I have attached the schematics and a board image. Both the schematic and board image are licensed: CC BY-NC-SA 4.0
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