Scc Parameter Ram Memory Map; Data Buffer Function Code Register (Tfcr, Rfcr) - Motorola MC68302 User Manual

4.5.6 SCC Parameter RAM Memory Map
Each SCC maintains a section in the dual-port RAM called the parameter
RAM. Each SCC parameter RAM area begins at offset $80 from each SCC
base area ($400, $500, or $600) and continues through offset $BF. Refer to
Table 2-8 for the placement of the three SCC parameter RAM areas. Part of
each SCC parameter RAM (offset $80-$9A), which is identical for each pro-
tocol chosen, is shown in Table 4-2. Offsets $9C-$BF comprise the protocol-
specific portion of the SCC parameter RAM and are discussed relative to the
particular protocol chosen.
Table 4-2. SCC Parameter RAM Memory Map
Address
Name
Width Description
SCC Base+80
*
RFCR Byte
Tx Function Code
SCC Base+81
*
TFCR Byte Tx Function Code
SCC Base+82
*
MRBLR Word
Maximum Rx Buffer Length
SCC Base+84
Word Rx Internal State
SCC Base+86 RBD# Byte
Rx Internal Buffer Number
SCC Base+87 Byte Reserved
sec
Base+as
2 Words Rx Internal Data Pointer
SCC Base+BC
Word Rx Internal Byte Count
SCC Base+BE
Word Rx Temp
SCC Base+90 Word Tx Internal State
SCC Base t92 TBD# Byte
Tx Internal Buffer Number
SCC Base+93
Byte Reserved
SCC Base+94 2 Words Tx Internal Data Pointer
SCC Base+98 Word Tx Internal Byte Count
SCC Base+9A Word Tx Temp
SCC Base+9C
First Word of Protocol-Specific Area
SCC Base+BF
Last Word of Protocol-Specific Area
*Initialized by the user (M68000 core).
The registers (see Table 4-2) that typically need to be accessed by the user
are described in the following paragraphs.
4.5.6.1 DATA BUFFER FUNCTION CODE REGISTER (TFCR, RFCR). This register
defines the address space of the receive (RFCR) and transmit (TFCR) data
buffers.
MOTOROLA
NOTE
The value of the function code register for any channel may be equal
to that of any other.
0
I
FC2 FCl FCO 0
I
0
I
0
I
0
MC68302 USER'S MANUAL 4-27