Motorola MCF5282, MCF5281 user manual Memory Base Address Register Rambar, Ipsbar Field Description

Models: MCF5282 MCF5281

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Register Descriptions

31

30

29

 

16

Field

BA31

BA30

 

 

 

 

 

 

 

 

Reset

0

1

 

 

 

 

 

 

 

 

R/W

 

 

 

R/W

 

 

 

 

 

 

 

15

 

 

1

0

Field

 

 

 

V

 

 

 

 

 

 

Reset

 

 

 

 

 

 

 

 

 

 

R/W

 

 

 

R/W

 

 

 

 

 

 

 

Address

 

 

 

IPSBAR + 0x000

 

 

 

 

 

 

 

 

 

 

Figure 8-1. IPS Base Address Register (IPSBAR)

 

 

 

Table 8-2. IPSBAR Field Description

 

 

 

 

Bits

Name

 

Description

 

 

 

31–30

BA

Base address. Defines the base address of the 1-Gbyte internal peripheral space. This is the

 

 

starting address for the IPS registers when the valid bit is set.

 

 

 

29–1

Reserved, should be cleared.

 

 

 

0

V

Valid. Enables/disables the IPS Base address region. V is set at reset.

 

 

0

IPS Base address is not valid.

 

 

1

IPS Base address is valid.

 

 

 

 

8.4.2Memory Base Address Register (RAMBAR)

The MCF5282 supports dual-ported local SRAM memory. This processor-local memory can be accessed directly by the core and/or other system bus masters. Since this memory provides single-cycle accesses at processor speed, it is ideal for applications where double-buffer schemes can be used to maximize system-level performance. For example, a DMA channel in a typical double-buffer (also known as a ping-pong scheme) application may load data into one portion of the dual-ported SRAM while the processor is manipulating data in another portion of the SRAM. Once the processor completes the data calculations, it begins processing the just-loaded buffer while the DMA moves out the just-calculated data from the other buffer, and reloads the next data block into the just-freed memory region. The process repeats with the processor and the DMA “ping-ponging” between alternate regions of the dual-ported SRAM.

The MCF5282 design implements the dual-ported SRAM in the memory space defined by the RAMBAR register. There are two physical copies of the RAMBAR register: one located in the processor core and accessible only via the privileged MOVEC instruction at CPU space address 0xC05, and another located in the SCM at IPSBAR + 0x008. ColdFire core accesses to this memory are controlled by the processor-local copy of the RAMBAR, while module accesses are enabled by the SCM's RAMBAR.

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MCF5282 User’s Manual

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Page 190
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Motorola MCF5282, MCF5281 user manual Memory Base Address Register Rambar, Ipsbar Field Description