
The PowerQUICC II
Once all the resets are
The MPC8260 can control the reset of the various communication peripherals through certain CPM I/O ports. When the PowerQUICC II is in reset state, and until it configures these I/O ports as outputs, these reset signals are activated.
System ClocksThe MPC8260 gets its reference clock in its CLOCKIN input pin from a 65.536 MHz reference oscillator.
The MPC8260 input pins MODCK[1:3], along with the MODCK_H field from the Reset Configuration Word define the input clock used for the SPLL and the default clock multiplication factors. The resulting internal system frequencies are:
•PowerPC core frequency: 196.608 MHz (x3)
•CPM frequency: 131.072 MHz (x2)
PCI Local Space MappingThe PowerPC local processor can address a 4 GB logical space. In this space, the following elements are mapped:
•The vector table (including the reset entry point)
•The MPC8260 internal registers
•The main SDRAM memory
•The FLASH memory
•The PCI bridge (the PowerSpan) and its
•The communication peripheral (QuadFALC)
When the MPC8260 boots, it is configured to select the FLASH memory, regardless of the address generated. This will allow the PowerPC to always find the boot start entry in the FLASH. After having booted, having executed a proper jump, and initialized the memory controllers, both the vector table address and the FLASH address can be configured and mapped in other areas: the developer will typically prefer to implement the vector table in a R/W memory device (the main memory SDRAM).
The MPC8260 includes 12 banks with their respective Chip Selects.
The memory mapping has been defined in a way that allows use of the MMU Block Address Translation (BAT) mechanism, which is simpler than the
Depending on the device selected, the corresponding memory area can be defined as “cachable” for better performance or must be set as “non cachable”. For instance, the FLASH memory can be cachable. The areas in the SDRAM that are only accessed by the
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