I realize that to use SPI I need to disable the initial I2C interface, and that I do this by setting bit 4 of register 3. But since SPI doesn't initially work, it appears that I have to use I2C to set that bit. So I have to use I2C just long enough to turn itself off so I can switch over to SPI.
There has got to be a smoother way to do this. Can I get the chip into SPI mode from an exclusively SPI connection? Can I use SPI to turn SPI on? I realize this sounds rather chicken & egg, but I'm not sure what else to do.
Alternatively, can I get the chip to initialize in SPI mode (i.e. to power up with that bit set), perhaps by hardware instead of software means, say by pulling some pin high or low? I see no such indication in the docs.
Thanks.