Hi,
If you are using BMP581 shuttle board, then please tie VDDIO to VDD 3V3 and also tie CS to VDD 3V3 for I2C communication. BMP581 needs both VDD and VDDIO to ramp up and be stabilized at their operating voltage level so that it can start its power-on reset (POR). If you don't connect VDDIO to 3V3, then BMP581 is not powered on. Therefore, I2C communication will not work.
Thanks.
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