Notes from AS3935 datasheet:
Register Map: Page 11, detailed version on Page 12

The SEN-39001 can be used with either I2C or SPI without modification, though pull-up resistors (10k) are
populated on the board by default. This doesn't seem to hinder operation at room temperature, but may
have a negative impact on performance in different operating situations. It may be necessary to remove
these resistors for your specific app. 

Connections should be made per the 'Circuit' description. This configuration is the setup that has been
tested by Playing With Fusion engineers.
