Memory Controller
MPC885 PowerQUICC Family Reference Manual, Rev. 2
15-42
Freescale Semiconductor
Figure 15-40. CS
x
Signal Selection
15.6.4.3
Byte-Select Signals (BST
x)
BRx[MS] of the accessed memory bank selects a UPM on the currently requested cycle. The selected UPM
affects only the assertion and negation of the appropriate BS signal; its timing as specified in the RAM
word. The state of each BS[0:3] signal depends on the value of each BSTx bit and the values of BRx[PS],
TSIZn, and A[30:31] in the current cycle.The BS signals are also controlled by the port size of the accessed
bank, the transfer size of the transaction, and the address accessed.
Figure 15-41
shows how UPMs control
BS signals.
Figure 15-41. BS
x
Signal Selection
UPMA
UPMB
GPCM
MUX
MS[0–1] in BRx
CS0
CS1
CS2
CS3
CS4
CS5
CS6
CS7
Switch
Bank Selected
MS[0–1]
Machine
00
GPCM
01
–
10
UPMA
11
UPMB
UPMA
UPMB
MUX
MS[0–1] in BRx
BS0
BS1
BS2
BS3
Bank Selected
PS[0–1] in BRx
A[30:31]
TSIZ[0:1]
Byte-Select
Logic
Summary of Contents for PowerQUICC MPC870
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Page 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
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Page 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Page 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
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Page 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
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