A.3. EEPROM contents

The Static Memory Expansion EEPROM is 256 bytes in size and contains 5 chip select information blocks, a manufacturer string and a checksum. The EEPROM is read and written using a serial bus implemented on HDRX signals MEMEXPB88 (SBSDA data) and MEMEXPB90 (SBSCL clock). The Logic Tile must implement a controller for these signals on Logic Tile signals Z216 and Z218.

Each chip select information block contains details about the memory devices accessed with the corresponding chip select signal. The organization of a chip select information block is listed in table Table A.2.

Figure A.3. Chip select information block

Chip select information block

Table A.2. Chip Select information block

FunctionAddress offsetValue
Memory Type0x0
0x0= Reserved
0x1= Static Disk On Chip
0x2= Static NOR flash
0x3= Static SRAM
0x4-0xFE = Reserved (used by dynamic memory expansion modules)
0xFF = Not fitted.
Memory Width0x01

Bits [3:0] indicate the chip-select width:

0= byte wide1= 16-bit wide2= 32-bit wide3= Reserved.

Bits [7:4] indicate the device memory width:

0= byte wide1= 16-bit wide2= 32-bit wide3= Reserved.
Access time0x02Two bytes containing the access time (tACC) decoded as a binary multiple of 100ps. Location 2 contains the LSB and location 3 contains the MSB. For example, a flash device with 120ns access is 1200 * 0.1ns. The decimal value is 1200 and the hex value is 0x04B0, therefore location 2 contains 0xb0 and location 3 contains 0x04.
Size0x04Four bytes containing the size of the memory in bytes. Location 4 is the LSB and location 7 is MSB.
Reserved0x08-0x0FEight bytes reserved for future expansion
Device string0x10-0x2FNull terminated string of up to 32 characters (31 characters + null character) containing the manufacturer name and part number.

The base address of the information block is determined by the device chip select used.

The contents of a typical static memory expansion EEPROM with devices on EXPnCS and CS4 is listed in Table A.3. Unused chip select blocks are filled with 0xFF.

Table A.3. Example contents of a static memory expansion EEPROM

Address offsetContentsContents
0x00EXPnCS memory type0x02 = Static NOR flash
0x01EXPnCS memory width0x12 - 32 bit chip select width, 16-bit device memory width
0x02EXPnCS access time in 0.1ns (LSB)0xb0 - LSB (of 1200 which 1200 * 0.1ns = 120ns access time)
0x03EXPnCS access time in 0.1ns (MSB)0x04 - MSB (of 1200 which 1200 * 0.1ns = 120ns access time)
0x04EXPnCS memory size in bytes (LSB)0x00
0x05EXPnCS memory size in bytes 0x00
0x06EXPnCS memory size in bytes0x00
0x07EXPnCS memory size in bytes (MSB)0x04 (0x04000000 Bytes = 64MBytes)
0x8-0xFReserved0xFF
0x10-0x2FEXPnCS memory device string"Intel GE28F256K3C120" + null character
0x30CS4 memory type0x01 = Static SRAM
0x31CS4 memory width0x02 - 32 bit wide
0x32CS4 access time in 0.1ps (LSB)0x26 - LSB (of 550 which 550 * 0.1ns = 55ns access time)
0x33CS4 access time in 0.1ps (MSB)0x02 - MSB (of 550 which 550 * 0.1ns = 55ns access time)
0x34CS4 memory size in bytes (LSB)0x00
0x35CS4 memory size in bytes 0x00
0x36CS4 memory size in bytes0x00
0x37CS4 memory size in bytes (MSB)0x20 (0x00200000 Bytes = 2MBytes)
0x38-0x3FReserved0xFF
0x40-0x5FCS4 memory device string"Samsung K6F8016U6A-F55" + null character
0x60CS5 memory type0xFF - not fitted
0x61CS5 memory width0xFF
0x62CS5 access time in 0.1ps (LSB)0xFF
0x63CS5 access time in 0.1ps (MSB)0xFF
0x64CS5 memory size in bytes (LSB)0xFF
0x65CS5 memory size in bytes 0xFF
0x66CS5 memory size in bytes0xFF
0x67CS5 memory size in bytes (MSB)0xFF
0x68-0x6FReserved0xFF
0x70-0x8FCS5 memory device string0xFF
0x90CS6 memory type0xFF - not fitted
0x91CS6 memory width0xFF
0x92CS6 access time in 0.1ps (LSB)0xFF
0x93CS6 access time in 0.1ps (MSB)0xFF
0x94CS6 memory size in bytes (LSB)0xFF
0x95CS6 memory size in bytes 0xFF
0x96CS6 memory size in bytes0xFF
0x97CS6 memory size in bytes (MSB)0xFF
0x98-0x9FReserved0xFF
0xA0-0xBFCS6 memory device string0xFF
0xC0CS7 memory type0xFF - not fitted
0xC1CS7 memory width0xFF
0xC2CS7 access time in 0.1ps (LSB)0xFF
0xC3CS7 access time in 0.1ps (MSB)0xFF
0xC4CS7 memory size in bytes (LSB)0xFF
0xC5CS7 memory size in bytes 0xFF
0xC6CS7 memory size in bytes0xFF
0xC7CS7 memory size in bytes (MSB)0xFF
0xC8-0xCFReserved0xFF
0xD0-0xEFCS7 memory device string0xFF
0xF0-0xFEBoard manufacturer string"ARM HBI0124A"+ null character
0xFFChecksum ByteThe LSB of the sum of bytes 0x00-0xFE

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