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11-92 SA-1100
Developer’s Manual
Peripheral Control Module
11.9.5 SDLC 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.
11.9.5.1 Address 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 76543210
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).