Method for input output expansion in an embedded system utilizing controlled transitions of first and second signals

A method for expanding input lines in an embedded system comprising a host controller, a peripheral device, and an expansion circuit, with first and second data lines coupled to the host controller, the peripheral device, and the expansion circuit, the method comprising:

• changing a signal level of a first signal on the first data line and a signal level of a second signal on the second data line such that a direct transition is made between a first state and a second state, in order to perform input from the expansion circuit;
• and
• changing a signal level of the first signal and a signal level of the second signal such that a direct transition is made between the first state and a third state before transitioning to the second state, in order to perform input from or output to the peripheral device.

A tangible computer readable storage medium having computer-executable instructions stored thereon, the computer-executable instructions readable by a computing system comprising one or more computing devices, wherein the computer-executable instructions are executable on the computing system in order to cause the computing system to perform a method comprising:

• changing a signal level of a first signal on a first output line coupled to a computing system and changing a signal level of a second signal on a second output line coupled to the computing system such that a direct transition is made between a first state and a second state, in order to perform output to an expansion device coupled to the computing system;
• and
• changing a signal level of the first signal on the first output line and the signal level of the second signal on the second output line such that a transition is made between the first state and a third state before transitioning to the second state, in order to perform input from or output to a peripheral device coupled to the computing system.