> The compass (AK8963) has a reset line, the other two have no reset line at all. Your best bet is to drop VCC, but what are the chances the hardware guy just t

> The compass (AK8963) has a reset line, the other two have no reset line at all. Your best bet is to drop VCC, but what are the chances the hardware guy just tied them to the power bus and left it at that? That is, if you also have even more circuitry to disable the bus pullups; otherwise they will continue to power the device via clamping diodes, potentially calling further confusion. The hardware guys don't implement I2C slave power control for a reason: it gets bloody expensive real fast - both in terms of BOM cost and PCB estate. Having said that, the lack of a RESET line on many I2C slaves is just ridiculous. I have a sticker on my monitor that says "fix the hanging MMA8451Q bug"; it's been there for at least three months. The very thought of debugging I2C transactions makes me stop even trying.