Systems, methods, and apparatus for implementing hardware flow control between devices coupled through a serial peripheral interface. A method for transmitting information using a serial peripheral interface includes initiating an exchange of data over one or more data lines of a serial peripheral interface bus by asserting a first voltage state on a slave select line, transmitting data and clock signals over the serial peripheral interface bus while the slave select line remains at the first voltage state, refraining from transmitting data and clock signals over the serial peripheral interface bus when the slave select line transitions to a second first voltage state, receiving data at a slave device into a receive buffer while the slave select line remains at the first voltage state, and asserting the second voltage state on the slave select line when occupancy of the receive buffer reaches or exceeds a threshold occupancy level.