Character counter and match registers in a serial interface

Abstract

A method is described for controlling commands and data in a serial data stream received by a serial controller in a serial interface. A character count register is programed with a maximum number of characters that a serial controller will send to a direct memory access controller (DMAC) before sending an end of frame (EOF) indication. Characters in an incoming data stream are counted using the character count register. An EOF signal is passed to the DMAC after the maximum number of characters programmed in the character count register have been written to a direct memory access (DMA) buffer. The character count register is reset any time the serial controller passes an EOF to the DMAC. In one embodiment, a character is programmed into a match register. Data in an incoming data stream is compared with the character in the match register. When a character in the incoming data stream matches the character programmed in the match register, a match bit is set corresponding to the match register. The match bit as part of a next end of frame (EOF) indication sent by a serial controller to a direct memory access controller (DMAC).