Systems and methods for chip operation using serial peripheral interface (SPI) without a chip select pin

Systems and methods for chip operation using serial peripheral interface (SPI) without a chip select pin are disclosed. A communication link between a host and a device may include a clock line, a host to device line, and a device to host line. The host may signal a start or stop condition using the clock line and the device may send an acknowledgment of the host's signaling through the device to host line. Once acknowledgment is made, the host may then signal on the host to device line using a protocol such as SPI.