5.2.1 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.

Table 5-2. 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

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 5-3. 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
2047 1FFD 5FFF 5FFE 5FFD 5FFC 1FFC 1FFF 1FFE 1FFD 1FFC
2048 0003 6003 6002 6001 6000 0002 2003 2002 2001 2000
2049 0007 6007 6006 6005 6004 0006 2007 2006 2005 2004
4094 1FFB 7FFB 7FFA 7FF9 7FF8 1FFA 3FFB 3FFA 3FF9 3FF8
4095 1FFF 7FFF 7FFE 7FFD 7FFC 1FFE 3FFF 3FFE 3FFD 3FFC