Patent ID: 7366815

Claim:
A serial communications system which performs half-duplex channel serial communications, the serial communications system comprising: a host apparatus configured to send first data; a plurality of slave apparatuses each configured to return second data in response to the first data sent from the host apparatus; a master circuit connected to the host apparatus and configured to perform a first master operation using the first data from the host apparatus and a second master operation to transmit to the host apparatus the second data sent from an arbitrary one of the plurality of slave apparatuses; a plurality of slave circuits connected to the plurality of slave apparatuses on a one-to-one basis and each slave circuit being configured to perform a first slave operation to send the first data to a plurality of the slave apparatuses including a designated slave apparatus in response to the first master transmission operation and a second slave operation to cause the master circuit to perform the second master operation; and a transmission path configured to connect the master circuit to the slave circuit, wherein in the first master operation, the master circuit receives the first data from the host apparatus, superimposes the first data on a clock signal to generate a first serial data signal, and transmits the first serial data signal to the plurality of slave circuits via the transmission path, and wherein the slave circuit is configured to superimpose the second data on the first serial data signal during a low level of the clock signal, to generate a second serial data signal, and transmit the second serial data signal to the master circuit via the transmission path.