MVME5100 Single Board Computer Programmer's Reference Guide

Software Considerations
Notes 1. Use tRAS from the SDRAM block that has the slowest
tRAS.
2. tRAS_CLK is tRAS expressed in CLK periods.
3. Use tRP from the SDRAM block that has the slowest tRP.
4. tRP_CLK is tRP expressed in CLK periods.
5. Use tRCD from the SDRAM block that has the slowest
tRCD.
6. tRCD_CLK is tRCD expressed in CLK periods.
7. Use tRC from the SDRAM block that has the slowest tRC.
8. tRC_CLK is tRC expressed in CLK periods.
9. Remember that CLK is the Hawk’s 60x clock input pin.
5. Determine the size for each block that is present.
(Do not actually program the Hawk’s size bits at this point. You use
this information to program them later.)
Each block’s size can be determined using the following algorithm:
a. Calculate the number of rows in each device using SPD byte 3.
If the number of rows is ROWS and the value in SPD byte 3 is R,
then ROWS=2 R .
b. Calculate the number of columns in each device using SPD byte
4. If the number of columns is COLUMNS and the value in SPD
byte 4 is C, then
COLUMNS=2 C .
c. Calculate the total number of addresses within each device. If the
total number of addresses in a device is A, then
A=ROWS X COLUMNS
d. Calculate the total number of locations in the block using the
results of step 3 and SPD byte 17. If the total number of locations
in the block is L, and the value in byte 17 is 4, then
L = A x 4
or
L = 2 R x 2 C x 4
(Note that the Hawk only works if byte 17 is 4).
e. Obtain the primary device width from SPD byte 13.
f. Determine the size bits based on the results of steps d and e using
the table on the next page.
http://www.motorola.com/computer/literature 3-81
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