Relationship Between Data Bus Widths And Control Signals; Figure 4.16-1 Data Bus Widths And Control Signals In Usual Bus Interface; Figure 4.16-2 Data Bus Widths And Control Signals In Dram Interface - Fujitsu MB91F109 FR30 Hardware Manual

4.16 Relationship between Data Bus Widths and Control Signals

Data bus control signals (WR0X-WR1X, CS0H, CS0L, CS1L, CS1H, DW0X, and DW1X)
always correspond to data bus byte locations on a one-to-one basis, regardless of big
and little endians and data bus widths.
Relationship between Data Bus Widths and Control Signals
The following outlines the byte locations of the data buses of this part number used in the
specified data bus width and the control signals corresponding to those locations for each bus
mode.
Data bus widths and control signals for usual bus interface

Figure 4.16-1 Data bus Widths and Control Signals in Usual Bus Interface

Data bus widths and control signals in DRAM interface

Figure 4.16-2 Data Bus Widths and Control Signals in DRAM Interface

Table 4.16-1 outlines the bus widths and control signals.
4.16 Relationship between Data Bus Widths and Control Signals
16-bit bus width
Data bus Control signal
D31
WR0X
WR1X
D16
16-bit bus width
Data bus Control signal
D31
CASL WEL
CASH WEH
D16
8-bit bus width
Data bus Control signal
D31
WR0X
D24
(D23 to D16 are unused.)
8-bit bus width
Data bus Control signal
D31
CAS WE
D24
(D23 to D16 are unused.)
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