Communications Processor
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
18-13
18.7.2
The Buffer Descriptor (BD)
The USB, SCCs, SMCs, SPI, IDMA, PIP, and I
2
C use buffer descriptors (BDs) to define the interface to
buffers. BDs can be placed in any unused area of the dual-port RAM.
Table 18-9
shows the general BD
structure common to these controllers.
18.7.3
Parameter RAM
The CPM maintains a section of dual-port RAM called the parameter RAM. It contains parameters for
USB, SCC, SMC, SPI, I
2
C, and IDMA channel operation.
Table 18-10
shows the parameter RAM memory
map.
Table 18-9. General BD Structure
BD Base Offset
Field
0x00
Status and control
0x02
Data length
0x04
High-order of buffer pointer
0x06
Low-order of buffer pointer
Table 18-10. Parameter RAM Memory Map
Offset from IMMR
Page
Offset from DPRAM_base
Controller/Peripheral
0x3C00
1
0x1C00—0x1C7F
USB
0x1C80—0x1CAF
I
2
C default area
0x1CB0—0x1CBF
Miscellaneous
0x1CC0—0x1CFF
IDMA1
0x3D00
2
0x1D00—0x1D7F
SCC2
0x1D80—0x1DAF
SPI default area
0x1DB0—0x1DBF
RISC timer table
0x1DC0—0x1DFF
IDMA2
0x3E00
3
0x1E00—0x1E7F
SCC3
0x1E80—0x1EBF
SMC1
0x1EC0—0x1EFF
Reserved
0x3F00
4
0x1F00—0x1F7F
SCC4
0x1F80—0x1FBF
SMC2/PIP
0x1FC0—0x1FFF
Reserved
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 ...
Page 1336: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 16 Freescale Semiconductor ...
Page 1358: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 38 Freescale Semiconductor ...
Page 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
Page 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...