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

A computer-implemented method, comprising:

• reading data on a first data line and a second data line, wherein the first data line couples a first terminal of a microcontroller to a first terminal of a peripheral device and a first terminal of an expansion device and wherein the second data line couples a second terminal of the microcontroller to a second terminal of the peripheral device and a second terminal of the expansion device;
• detecting transitions on the first data line and the second data line;
• in response to detecting a first transition on the first data line and the second data line by the expansion device, reading data from additional data lines using the expansion device, wherein the microcontroller is configured to not include the first transition if the data is intended for reading by the peripheral device;
• and
• in response to detection of a second transition on the first data line and the second data line by the expansion device, writing data to the additional data lines using the expansion device.

A computer readable storage device having instructions stored thereon that, in response to execution by a computing device, cause the computing device to perform operations comprising:

• reading data from a first data line coupling the computing device to a peripheral device and an expansion device, wherein the peripheral device is configured to read data from the first data line in response to detecting a pulse;
• detecting a particular transition on the first data line by the expansion device during an interval between pulses, wherein the particular transition indicates that subsequent data on the first data line is intended for the expansion device and the computing device is configured to exclude the particular transition in data intended for reading by the peripheral device;
• and
• in response to detecting the transition on the first data line, performing a function.