CONTROLLING POWER STATES OF A DEVICE

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for controlling power states of a device. In one aspect, a circuit is configured to perform operations comprising: receiving, on a data pin of an SPI control interface, a command to enter a reduced power mode; determining that a select signal on a select pin of the SPI control interface has been released; in response to receiving the command to enter the reduced power mode and determining that the select signal has been released, causing the circuit to enter the reduced power mode; determining that the select signal on the select pin of the SPI control interface has been asserted; and in response to determining that the select signal on the select pin has been asserted, causing the circuit to exit the reduced power mode.