IIC bus communication system capable of suppressing freeze of IIC bus communication due to a noise and method for controlling IIC bus communication
View Patent ↗Multiple master devices and multiple slave devices are connected in parallel to two bus lines including a SCL line 1 and a SDA line 2 , and a pullup resistor is connected between the bus lines and a power source. A state detector detects a frozen state on the basis of the states of the SCL line and SDA line and outputs a freeze detection signal, and it detects a freeze released state so as to output a freeze-release detection signal. A pulse generator supplies a pulse signal corresponding to a clock signal to the SCL line in accordance with the freeze-release detection signal. A reset signal generator sends a reset signal to the multiple master devices in accordance with the freeze-release detection signal. The multiple master devices return to the normal communication state in accordance with the supply of the reset signal. It is possible to restore the system even when the slave device returns an acknowledge signal for an incorrect bit and the IIC bus communication freezes.
1. An IIC bus communication system comprising:
two bus lines including a SCL (serial clock) line and a SDA (serial data) line;
multiple master devices connected in parallel to the bus lines;
a state detector for detecting a frozen state of an IIC bus communication on the basis of the states of the SCL line and the SDA line so as to output a freeze detection signal, and detecting the state where the frozen state is released so as to output a freeze-release detection signal;
a pulse generator for supplying a pulse signal corresponding to a clock signal with respect to the SCL line in accordance with the freeze detection signal outputted from the state detector; and
a reset signal generator for supplying a reset signal to the multiple master devices in accordance with the freeze-release detection signal outputted from the state detector, wherein the multiple master devices return to a normal communication state in accordance with the supply of the reset signal.
2. The IIC bus communication system according to claim 1 , wherein the state detector detects the frozen state by detecting that predetermined states of the SDA and SCL continue for a predetermined period.
3. Equipment for a IIC bus communication system, comprising a device that is operated or controlled electrically in the IIC bus communication system according to claim 2 ,
wherein the device is configured as a slave device.
4. Equipment for a IIC bus communication system, comprising a device that is operated or controlled electrically in the IIC bus communication system according to claim 1 ,
wherein the device is configured as a slave device.
5. An IIC bus communication control method for controlling an IIC bus communication system comprising:
two bus lines including a SCL line and a SDA line; and
multiple master devices connected in parallel to the bus lines;
the method comprising the steps of:
monitoring states of the SCL line and the SDA line;
detecting the frozen state of an IIC bus communication and the state where the frozen state is released, on the basis of the states of the SCL line and the SDA line;
when the frozen state is detected, supplying a pulse signal corresponding to the clock signal to the SCL line; and
when detecting the state where the frozen state is released, sending a reset signal to the multiple master devices so that the multiple master devices return to a normal communication state.
6. The IIC bus communication control method according to claim 5 , wherein the frozen state is detected by detecting that predetermined states of the SDA and the SCL continue for a predetermined period.