Fujitsu FR81S User Manual
CHAPTER 45: FLASH MEMORY
2. Features
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : FLASH MEMORY
FUJITSU SEMICONDUCTOR CONFIDENTIAL
4
2. Features
This section explains features of the flash memory.
Usable capacity:
MB91F522 : 256Kbytes+64Kbytes (large sectors 128K × 2 + small sectors16K × 4)
MB91F523 : 384Kbytes+64Kbytes (large sectors 128K × 3 + small sectors16K × 4)
MB91F524 : 512Kbytes+64Kbytes (large sectors 128K × 4 + small sectors16K × 4)
MB91F525 : 768Kbytes+64Kbytes (large sectors 128K × 6 + small sectors16K × 4)
MB91F526 : 1024Kbytes+64Kbytes (large sectors 128K × 8 + small sectors16K × 4)
Since this series has ECC code storage, there are 6 bits of built-in flash memory for every 4 bytes described
above.
* The sector itself has 64KB(large sector)/8KB(small sector) capacity, but the pair of sectors (odd and even)
is alternately mapped word-by-word in the address space so that the sectors are to be used in 128KB(large
sectors)/16KB(small sectors) in real use.
High speed operation :
Reading at the word (32-bit) unit can be performed in 1 cycle at 80MHz.
Write from external :
Possible from ROM writer
Operation mode :
1. CPU-ROM mode
(CPU / DMA accesses the flash memory. Read-only )
2. CPU programming mode
(CPU accesses the flash memory. Read/Write/Erase)
3. Flash memory mode (flash memory accessible from external)
Can be read, written, or erased (automatic algorithm*) by CPU
Can be read, written, or erased (automatic algorithm*) by ROM writer
Security function
⋅
In order to prevent the content of flash memory from being read by a third party, when security is on,
operation from external source after instruction fetch and writing/erasing other than chip erase are
suppressed.
⋅
After password authentication when using the on chip debugger (OCD), this can be read externally using
the OCD even when security is on.
Error correction code (ECC) security function
⋅
There is an error correction code (ECC) function that corrects errors of up to one bit in each word. (A
function for detecting 2-bit errors is not provided.) Errors are automatically corrected during read.
Furthermore, ECC codes are automatically added when writing to flash memory. Because there is no
read cycle penalty due to error correction, no consideration needs to be given to error correction penalties
during software development.
*: Automatic algorithm = Embedded Algorithm
MB91520 Series
MN705-00010-1v0-E
1925