AMD RS690M, Technical Reference Manual

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41978 AMD RS690M Databook 3.06 © 2008 Advanced Micro Devices, Inc.
3-18 Proprietary
Strapping Options
3.15 Strapping Options
The RS690M provides strapping options to define specific operating parameters. The strap values are latched into internal
registers after the assertion of the POWERGOOD signal to the RS690M.
Table 3-17, “Strap Definitions for the
RS690M,” shows the definitions of all the strap functions. These straps are set by one of the following four methods:
•
Allowing the internal pull-up resistors to set all strap values to “1” automatically.
•
Attaching pull-down resistors to specific strap pins listed in Table 3-17 to set their values to “0”.
•
Downloading the strap values from an I
2
C serial EEPROM (for debug purpose only; contact your AMD CSS
representative for details).
•
Setting through an external debug port, if implemented (contact your AMD CSS representative for details).
All of the straps below are defined active low. They are pulled up internally by default, so that no external pull-ups are
required to select “1”s for those straps. To select “0”s, the strap pins must be pulled down to VSS through resistors.
During reset, the strap pins are undriven, allowing either an internal pull-up to pull a pin to “1” or an external pull-down to
pull a pin to “0.” The values on the strap pins are then latched into the device and used as operational parameters.
However, for debug purposes, those latched values may be overridden through an external debug strap port or by a
bit-stream downloaded from a serial EEPROM.
Table 3-17 Strap Definitions for the RS690M
Strap Function Strap Pin Description
STRAP_DEBUG_BUS_EN# DFT_GPIO5 For RS690T:
Enables debug bus output via the memory I/O pads.
0: Use the memory data bus for debug bus output
1: Use default values (Default)
(See debug bus specification documents for more details.)
For RS690M:
This is a reserved strap and no strap resistor should be connected to it.
GPPSB_LINK_CONFIG DFT_GPIO[4:2] Southbridge and General Purpose Link Configuration.
See
Table 3-18 below for details.
LOAD_ROM_STRAPS# DFT_GPIO1 Selects loading of strap values from EEPROM
0: I
2
C master can load strap values from EEPROM if connected, or use default values
if not connected
1: Use default values (Default)
SIDE_PORT_EN# DFT_GPIO0 For the RS690T:
Indicates if memory side port is available or not
0: Memory side port available
1: Memory side port NOT available (Default)
For the RS690M:
This is a reserved strap and no strap resistor should be connected to it.