Patent ID: 7603501

Claim:
A communication circuit of a serial peripheral interface (SPI) device comprising: a master device comprising an SPI bus control unit, the SPI bus control unit comprising a chip select terminal; and a plurality of slave devices each comprising an SPI bus control unit, one of the slave devices comprising a plurality of general purpose input/output (GPIO) pins, the SPI bus control unit of each of the slave devices comprising a control terminal, the chip select terminal of the master device connected to the control terminal of the slave device having the GPIO pins, the GPIO pins respectively connected to the control terminals of the SPI bus control units of other slave devices; wherein the master device sends an instruction having an address signal to the slave device having the GPIO pins, the slave device having the GPIO pins compares the address signal of the instruction from the master device with its own address, if the addresses are identical, the slave device having the GPIO pins carries out the instruction from the master device and communicates with the master device, otherwise the slave device having the GPIO pins transmits the address signal of the instruction to the control terminals of the other slave devices through the GPIO pins, the other slave devices compare the address signal of the instruction from the master device with their own address, the slave device having the identical address carries out the instruction from the master device and communicates with the master device.