Line Read Burst (2-1-1-1), External Termination; Allowable Line Access Patterns - Motorola ColdFire MCF5281 User Manual

CSCRn[BSTR,BSTW]. A line access to a burst-inhibited region first accesses the
MCF5282 bus encoded as a line access. The SIZ[1:0] encoding does not exceed the
programmed port size. The address changes if internal termination is used but does not
change if external termination is used, as shown in Figure 13-12 and Figure 13-13.
13.4.7.1 Line Transfers
A line is a 16-byte-aligned, 16-byte value. Despite the alignment, a line access may not
begin on the aligned address; therefore, the bus interface supports line transfers on multiple
address boundaries. Table 13-4 shows allowable patterns for line accesses.
13.4.7.2 Line Read Bus Cycles
Figure 13-12 and Figure 13-13 show a line access read with zero wait states. The access
starts like a basic read bus cycle with the first data transfer sampled on the rising edge of
S4, but the next pipelined burst data is sampled a cycle later on the rising edge of S6. Each
subsequent pipelined data burst is single cycle until the last one, which can be held for up
to two CLKOUT cycles after TA is asserted. Note that CSn are asserted throughout the
burst transfer. This example shows the timing for external termination, which differs from
the internal termination example in Figure 13-13 only in that the address lines change only
at the beginning (assertion of TS and TIP) and end (negation of TIP) of the transfer.
CLKOUT
A[31:0], SIZ[1:0]
R/W
TIP
TS
CSn, BSn, OE
D[31:0]
TA
Figure 13-12. Line Read Burst (2-1-1-1), External Termination
MOTOROLA
Table 13-4. Allowable Line Access Patterns
A[3:2]
00
01
10
11
S0 S1 S2 S3
Read
Chapter 13. External Interface Module (EIM)
Longword Accesses
0–4–8–C
4–8–C–0
8–C–0–4
C–0–4–8
S4 S5 S6 S7 S8
Read
Read
Data Transfer Operation
S9 S10 S11 S12 S13
Read
13-11