This problem is very easily solved by making a state machine for each function. The realistic timer interrupt interval for this process is more likely to be 5 milliseconds. 1 microsecond is rediculous - that is less than one machine cycle on a standard 8052 with 11.0952 MHz oscillator. At 5 milliseconds you can setup the timer interrupt to call the state machine modules for each of the four inputs at each timer interrupt. Alternatively you could setup the timer interrupt at 1 millisecond and call one of the state machine tasks at each interrupt time in a round robin fashion.

This task requires two parts. One of design and approach methodology and the other to actually code it up. I would be happy to do one or both of the tasks at standard consulting rates.

I tend to agree that taking on the job of making a microcontroller appear to do many things at one time would be a daunting task for a beginner. But it is possible to do it with careful exercise using efficient state machine type design. Unfortunately the task of trying to teach how to do state machine coding is too complex to do in little forum text boxes.

There is also another issue here too. If the "bible" is too complex to for you to understand and use as a guide and learning tool then I can assure you that trying to get across how state driven code design is done will be very difficult for you. I have encountered many times that the design of complex code that I have implemented for clients that follows timer driven state machine design, whilest straight forward for a coding expert to follow, was just too much for the client to even begin to understand how it worked.

I guess that's why there is a ready marketplace for consultants.

Michael Karas