Intel SA-1100 manual Address Match Value AMV, SDCR2, Amv

Peripheral Control Module

11.9.5SDLC Control Register 2

SDLC control register 2 (SDCR2) contains the 8-bit address match value field that is used by the SDLC to selectively receive frames.

11.9.5.1Address 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 looks for the next start flag in the incoming data stream. One special address exists that 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 for the next frame that occurs following its update.

The following table shows the address match value field within SDLC control register 2. The reset state of AMV is unknown (indicated by question marks) and must be initialized before enabling the SDLC. Note that SDCR2 may be written while the SDLC is enabled to allow the address match value to be changed during active receive operation.

Address: 0h 8002 0068					SDCR2		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
		address matches, store frame address, control, and data in receive FIFO; if address
		does not match, ignore frame and search for next flag.
		Note: An address of 0hFF (all ones) in the incoming frame automatically generates a
		match (AMV is ignored).

11-92 SA-1100 Developer’s Manual