Embedded SRAM (eSRAM) Controllers
UG0331 User Guide Revision 15.0
190
ECC Checker and AHB Read Data Bus (HRDATA) Generator:
In SECDED-ON mode, the ECC
Checker takes data (DO) from the memory as the input during the read or read-modify-write cycle and
checks for errors. One-bit errors detected are corrected.
If errors of more than one bit are detected, they are not corrected. In SECDED-OFF mode, the read out
data is directly given as output from this block. Error Status Signals are set if any errors are detected.
Error Status Signals:
Error bits are inputs from the ECC Checker. If one error bit is High, it causes the
EDAC_1E signal to be High. In this case, there is no HRESP as the error is corrected. If there are two-bit
errors, it cause the EDAC_2E signal to be High. In this case, HRESP is set High because the error is not
corrected. The EDAC_1E and EDAC_2E signals are used to increment the ECC error counters within the
SYSREG block (and the failing address is also passed to the SYSREG block). When the HRESET to
ESRAMTOAHB is applied, it resets the EDAC address register which is maintained in ESRAMTOAHB
and it does not clear the contents of SRAM. EDAC error counters are maintained in System Register
which can be cleared either through same HRESET or by setting the
.
6.2.1
Memory Organization
The 40 KB of eSRAM memory is divided into two banks: 32 KB and 8 KB, to store 32 bits of data and 7
check bits in SECDED-ON mode. Physically, however, the memory is organized as
4096 × 40, which is 4096 × 5 bytes. When ECC is enabled, the fifth byte stores ECC values for the 32
bits of data. When ECC is disabled, the fifth byte location is used to create an additional 2 KB of user
memory. Four locations are used for each 32-bit word.
The following table shows the organization of 4096 × 40 bits in SECDED-ON mode. The total size of the
SRAM in the table is 40 KB. The locations show the memory used for the 32 KB block. ECC represents
the 7-bit ECC.
The following table shows the organization of 4096 × 40 bits in SECDED-OFF mode. The total size of the
SRAM in the table is 40 KB. The red locations show the memory used for the 32 KB block. The green
locations show memory used for the upper 8 KB block.
Table 119 •
SRAM Organization in SECDED-ON Mode
RAM 4096X40_1
4096 x 40 Bits
RAM 4096X40_0
4096 x 40 Bits
Location Byte 4
Byte 3
Byte 2
Byte 1
Byte 0
Byte 4
Byte 3
Byte 2 Byte 1
Byte 0
0
ECC
4003
4002
4001
4000
ECC
0003
0002
0001
0000
1
ECC
4007
4006
4005
4004
ECC
0007
0006
0005
0004
2046
ECC
5FFB
5FFA
5FF9
5FF8
ECC
1FFB
1FFA
1FF9
1FF8
2047
ECC
5FFF
5FFE
5FFD
5FFC
ECC
1FFF
1FFE
1FFD
1FFC
2048
ECC
6003
6002
6001
6000
ECC
2003
2002
2001
2000
2049
ECC
6007
6006
6005
6004
ECC
2007
2006
2005
2004
4094
ECC
7FFB
7FFA
7FF9
7FF8
ECC
3FFB
3FFA
3FF9
3FF8
4095
ECC
7FFF
7FFE
7FFD
7FFC
ECC
3FFF
3FFE
3FFD
3FFC
Table 120 •
SRAM Organization in SECDED-OFF Mode
RAM 4096X40_1
4096 x 40 Bits
RAM 4096X40_0
4096 x 40 Bits
Location
Byte 4
Byte 3
Byte 2
Byte 1
Byte 0
Byte 4
Byte 3
Byte 2
Byte 1
Byte 0
0
0001
4003
4002
4001
4000
0000
0003
0002
0001
0000
1
0005
4007
4006
4005
4004
0004
0007
0006
0005
0004
2046
1FF9
5FFB
5FFA
5FF9
5FF8
1FF8
1FFB
1FFA
1FF9
1FF8
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