Intel SA-1100 manual HSCR1, Search for the next preamble, 11-116

Peripheral Control Module

11.10.7HSSP Control Register 1

HSSP control register 1 (HSCR1) contains the 8-bit address match value field that is used by the HSSP to selectively receive frames.

11.10.7.1Address Match Value (AMV)

The 8-bit address match value (AMV) field is programmed with an address value that is used to selectively store only the data within receive frames that have the same address value. The address match enable (AME) bit must be set to enable this function. For incoming frames, which have the same address value as the AMV field, the frame’s address, control, and data are stored in the receive FIFO. For those that do not, the remainder of the frame is ignored and the receive logic switches to hunt mode, looking for the preamble in the incoming data stream. One special address exists, which is always matched by the address match logic regardless of the value programmed in AMV. When address matching is enabled, whenever a frame is received with an address containing all ones (11111111), the value programmed in AMV is ignored and the frame data is automatically stored in the receive FIFO. The address value is contained within the first byte of data in a frame following the flag. AMV can be written at any time and is used for comparison with the next frame, which occurs following its update.

The following table shows the address match value field within HSSP control register 1. The reset state of AMV is unknown (indicated by question marks) and must be initialized before enabling the HSSP. Note that HSCR1 may be written while the HSSP is enabled to allow the address match value to be changed during active receive operation.

Address: 0h 8004 0064					HSCR1		Read/Write
Bit	7	6	5	4	3	2	1	0
					AMV
Reset	?	?	?	?	?	?	?	?

Bit	Name	Description
7..0	AMV	Address match value.
		The 8-bit value used by receiver logic to compare to address of incoming frames. If
		AME=1 and AVM matches the address of the incoming frame, store the frame address,
		control, and data in receive FIFO; if address does not match, ignore the frame and
		search for the next preamble.
		Note: An address of 0hFF (all ones) in the incoming frame automatically generates a
		match (AMV is ignored).

11-116 SA-1100 Developer’s Manual