Control method to expand function of mobile information devices
Original Publication Date: 2000-Jul-01
Included in the Prior Art Database: 2003-Jun-19
Disclosed is a system for controlling bus interface mechanism on mobile information devices. Previously, bus interface mechanism for expansion unit is controlled by special control software. This system replaces many software routine with hardware (sequencer) and it not only reduce software code, but also increase system reliability. Many information devices, like portable computers, have expansion unit as option to expand their functionality, they are connected with expansion bus. To expand internal system bus of the device, it has to have special mechanism to connect or disconnect the system bus in proper sequence. This mechanism is controlled by software on current products and it requires complicated control software, and it has possibility to cause malfunction if some event, such as hardware interrupt, CPU reset etc., interrupt while software is processing the mechanism. This new method solves these issues by having dedicated controller to control the bus isolation mechanism in the system unit. It controls the bus isolation mechanism in proper sequence automatically and takes over most of function of the control software. Using the controller can extremely simplify the control software and it improves software reliability. This controller does not affect CPU reset and hardware reset signal, and all of the bus control sequence completes in any case, this reduces possibility that the bus isolation mechanism get into illegal state, and this improves system reliability.