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TMS320C6713B Floating-Point Digital Signal Processor (Rev. A)

TMS320C6713B Floating-Point Digital Signal Processor (Rev. A)

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SPRS294A − OCTOBER 2005 − REVISED NOVEMBER 2005<br />

cache configuration (CCFG) register description<br />

The C6713B device includes an enhancement to the cache configuration (CCFG) register. A “P” bit<br />

(CCFG.31) allows the programmer to select the priority of accesses to L2 memory originating from the transfer<br />

crossbar (TC) over accesses originating from the L1D memory system. An important class of TC accesses is<br />

EDMA transfers, which move data to or from the L2 memory. While the EDMA normally has no issue accessing<br />

L2 memory due to the high hit rates on the L1D memory system, there are pathological cases where certain<br />

CPU behavior could block the EDMA from accessing the L2 memory for long enough to cause a missed deadline<br />

when transferring data to a peripheral such as the McASP or McBSP. This can be avoided by setting the P bit<br />

to “1” because the EDMA will assume a higher priority than the L1D memory system when accessing L2<br />

memory.<br />

For more detailed information on the P-bit function and for silicon advisories concerning EDMA L2 memory<br />

accesses blocked, see the TMS320C6713, <strong>TMS320C6713B</strong> <strong>Digital</strong> <strong>Signal</strong> <strong>Processor</strong>s Silicon Errata (literature<br />

number SPRZ191).<br />

31 30 10 9 8 7 3 2 0<br />

P † Reserved IP ID Reserved L2MODE<br />

R/W-0 R-x W-0 W-0 R-0 0000 R/W-000<br />

Legend: R = Readable; R/W = Readable/Writeable; -n = value after reset; -x = undefined value after reset<br />

† This device includes a P bit.<br />

Figure 14. Cache Configuration Register (CCFG)<br />

Table 25. CCFG Register Bit Field Description<br />

BIT # NAME DESCRIPTION<br />

L1D requestor priority to L2 bit.<br />

31 P P = 0: L1D requests to L2 higher priority than TC requests<br />

P = 1: TC requests to L2 higher priority than L1D requests<br />

30:10 Reserved Reserved. Read-only, writes have no effect.<br />

Invalidate L1P bit.<br />

9 IP 0 = Normal L1P operation<br />

1 = All L1P lines are invalidated<br />

Invalidate L1D bit.<br />

8 ID 0 = Normal L1D operation<br />

1 = All L1D lines are invalidated<br />

7:3 Reserved Reserved. Read-only, writes have no effect.<br />

L2 operation mode bits (L2MODE).<br />

2:0 L2MODE<br />

000b = L2 Cache disabled (All SRAM mode) [256K SRAM]<br />

001b = 1-way Cache (16K L2 Cache) / [240K SRAM]<br />

010b = 2-way Cache (32K L2 Cache) / [224K SRAM]<br />

011b = 3-way Cache (48K L2 Cache) / [208K SRAM]<br />

111b = 4-way Cache (64K L2 Cache) / [192K SRAM]<br />

All others Reserved<br />

70 POST OFFICE BOX 1443 • HOUSTON, TEXAS 77251−1443

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