Apparatus and method for reading and writing remote registers on an

Abstract

A method and apparatus is disclosed for reading data from and writing data to remote registers that are dispersed throughout an integrated circuit chip. Regardless of the size or number of remote registers involved, the operation is accomplished using only two interconnect lines, plus a clock. Each remote register is associated with a unique address. During a write operation, a microprocessor loads the write data into a staging register, loads the destination address into a header generation register along with a read/write control bit, and loads a count value into a clock. Thereafter, the apparatus of the invention proceeds automatically, as the clock counts down, to shift the data onto a serial data line following a header. Each of the remote registers in the system are arranged serially, and each monitors the header information, comparing the address contained in the header with its own address. In the event of a match, the remote register selected is enabled to shift data serially into itself from the serial data line. During a read operation, the selected remote register shifts its data out onto the serial data line. The read data is ultimately shifted back into the staging register.