Freescale Semiconductor MPC8260 - Manual (Page 472)

Memory Controller
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
11-54 Freescale Semiconductor
• One quarter of a clock cycle later
• One half of a clock cycle later
Note the GPCM does not negate CS in back-to-back reads to the same device when in single
PowerQUICC II bus mode or in 60x-compatible bus mode with extended transfers enabled. When in strict
60x bus mode, however, the GPCM does negate CS in back-to-back reads. See
Section 4.3.2.1, “Bus
Configuration Register (BCR).”
Figure 11-41 shows a basic connection between the PowerQUICC II and an external peripheral device.
Here, CS (the strobe output for the memory access) is connected directly to CE of the memory device and
BCTL0 is connected to the respective R/W in the peripheral device.
Figure 11-41. GPCM Peripheral Device Interface
Figure 11-42 shows CS as defined by the setup time required between the address lines and CE. The user
can configure ORx[ACS] to specify CS to meet this requirement.
Figure 11-42. GPCM Peripheral Device Basic Timing (ACS = 1x and TRLX = 0)
11.5.1.2 Chip-Select and Write Enable Deassertion Timing
Figure 11-43 shows a basic connection between the PowerQUICC II and a static memory device. Here,
CS is connected directly to CE of the memory device. The WE signals are connected to the respective W
signal in the memory device where each WE corresponds to a different data byte.
Address
CE
R/W
Data
Peripheral
Data
BCTL0
CS
Address
PowerQUI
Clock
Address
PSDVAL
CS
R/W(BCTL0)
Data
ACS = 11
ACS = 10