4.0 S-LINK Usage Instructions

4.8 Data Width Control

Various data widths are permitted for an S-LINK. It may also be possible to switch between different data widths which have the same data transfer rate. Permitted configurations are shown in Table 7.

Unused data lines shall be left unconnected on the LSC and connected to GND on the LDC.

If an S-LINK has a switchable data width, the data width to be used is selected by setting the lines UDW[1..0] according to Table 8. The Data Width lines are sampled after a reset cycle and the S-LINK configured then. Note that the same code must be selected at each end of the S-LINK. If the codes do not match, the S-LINK may function incorrectly. The data width configurations which an S-LINK can support shall be detailed in the S-LINK Data Sheet.

TABLE 7. Permitted Data Width Configurations
Data Width Data lines used at LSC Data lines used at LDC
32-bit only UD[31..0] LD[31..0]
16-bit only UD[15..0] LD[15..0]
8-bit only UD[7..0] LD[7..0]
32-bit or
16-bit
UD[31..0]
UD[15..0]
LD[31..0]
LD[15..0]
16-bit or
8-bit
UD[15..0]
UD[7..0]
LD[15..0]
LD[7..0]
32-bit,
16-bit or
8-bit
UD[31..0]
UD[15..0]
UD[7..0]
LD[31..0]
LD[15..0]
LD[7..0]

TABLE 8. Data Width Selection Codes
Data Width UDW1 UDW0
32-bit 0 0
16-bit 0 1
8-bit 1 0
reserved 1 1

The S-LINK Interface Specification - 27 MARCH 1997

[Next] [Previous] [Up] [Top]

Data Width	Data lines used at LSC	Data lines used at LDC
32-bit only	UD[31..0]	LD[31..0]
16-bit only	UD[15..0]	LD[15..0]
8-bit only	UD[7..0]	LD[7..0]
32-bit or 16-bit	UD[31..0] UD[15..0]	LD[31..0] LD[15..0]
16-bit or 8-bit	UD[15..0] UD[7..0]	LD[15..0] LD[7..0]
32-bit, 16-bit or 8-bit	UD[31..0] UD[15..0] UD[7..0]	LD[31..0] LD[15..0] LD[7..0]