Expansion bridge apparatus and method for an I2C bus
View Patent ↗The present invention is an I 2 C (inter-IC control) bridge device which implements a communication protocol layered on top of a standard I 2 C protocol. The layered protocol used by the bridge device is termed the “Layered I 2 C Protocol”—abbreviated “LIP”. Thus the bridge device is called a “LIP bridge device”. The LIP bridge device provides I 2 C address extension, data integrity checking, and fault detection and isolation when inserted between an I 2 C bus master and it's intended target I 2 C device. Each LIP bridge device has at least two attached I 2 C busses—a parent bus and a child bus. The LIP bridge operates as a slave on its parent bus, and a master of its child bus. The Layered I 2 C protocol is specified to operate on a bus between one or more bus masters and the parent bus of one or more LIP bridge devices. The child bus is used for attaching multiple I 2 C devices and/or one or more LIP bridge devices. In an exemplary implementation, the LIP bridge device is constructed using a microcontroller to create a LIP bridge device with one parent and one child I 2 C bus port and a group of LIP bridge configuration pins. The parent bus traffic to a given LIP bridge device consists entirely of LIP packets, and the child bus traffic consists of standard I 2 C packets to communicate with standard child bus I 2 C devices. The child bus traffic may also consist of LIP packets to communicate with LIP bridges attached to the child bus. By design, the LIP packets and standard I 2 C transactions do not interfere with one another. The LIP bridge device interprets LIP command packets from a bus master and translates them into the intended I 2 C data stream that is then broadcast over the child bus. Likewise, data from the child bus is used to create LIP packets that are returned to the proper bus master. The use of LIP packets on a given I 2 C bus provides an extra level of I 2 C addressing.
1. A system comprising:
at least one host bus master operable to utilize a first communications protocol for communicating over a parent bus; and
at least two LIP bridge devices, each LIP bridge device including,
a first transceiver coupled to said host bus master over said parent bus, said host bus master utilizing said first communications protocol;
a second transceiver coupled to target devices over a child bus, said target devices utilizing a second communications protocol, said first communications protocol having a bridge device address field for addressing said bridge devices and a target device address field for addressing said target devices coupled to said child bus;
said at least two LIP bridge devices being coupled to said parent bus and said child bus, said at least two LIP bridge devices being operable to transmit messages between said host bus master and said target devices, each of said at least two LIP bridge devices being partnered to the other LIP bridge device, said host bus master being operable to use said at least two LIP bridge devices to determine if transactions through a particular LIP bridge are corrupted, said host bus master being operable to cross check data provided by each of said at least two LIP bridge devices to verify integrity of data received from said target devices, and each of said at least two LIP bridge devices being adapted to use partnering signals to reset the other LIP bridge device to isolate faults.
2. The system of claim 1 , wherein said host bus master is operable to hold a failed interconnected LIP bridge device in a reset state in which said failed interconnected LIP bridge device is electrically removed from said child bus.
3. The system of claim 2 , wherein said host bus master clears errors in said failed interconnected LIP bridge device with reset commands.
4. The system of claim 3 , wherein said host bus master is operable to access any target device on said child bus via any LIP bridge device connected to said parent bus and said child bus.
5. The system of claim 4 , wherein said host bus master performs every child bus read operation on each of said at least two LIP bridge devices to ensure data integrity.
6. The system of claim 5 , wherein each of said at least two LIP bridge devices are adapted to use partnering signals to disable the other LIP bridge device to isolate faults.