Overview Of Dual Operation Flash Memory - Fujitsu MB90335 Series Hardware Manual

CHAPTER 22 DUAL OPERATION FLASH MEMORY

22.1 Overview of Dual Operation Flash Memory

22.1 Overview of Dual Operation Flash Memory
Dual Operation Flash Memory is allocated to FF bank in CPU memory map. The function
of the flash memory interface circuit enables the read access from CPU and the program
access.
Dual Operation Flash consists of the upper bank (16 K bytes 5 2 + 4 K bytes 5 4) and
lower bank (4 K bytes 5 4), allowing concurrent execution of an erase/program and a
read in two banks, which is not allowed in conventional flash products.
■ Overview of Dual Operation Flash Memory
There are three ways of programming and erasing flash memory as follows:
1. Programming and erasing using parallel writer
2. Programming and erasing using serial writer
3. Programming and erasing by executing program
Programming and erasing flash memory are enabled by an instruction from the CPU via the flash memory
I/F circuit. This allows efficient reprogramming and programming data in the mounted state under CPU
control.
The minimum sectors are as compact as 4 kbytes that can be handled easily as program/data areas.
Data can be reprogrammed not only by program execution in RAM but also by program execution in flash
memory because of dual operation. In addition, an erase/write and reading of the different banks (the upper
and lower banks) can be executed concurrently.
Note: When one bank is in state of write/sector erase, the other bank cannot use it.
■ Features of Dual Operation Flash Memory
• 64 Kword x 8 bits/32 Kword x 16 bits (4 K x 4 + 16 K + 8 K x 2 + 4 K x 4) sector configuration
• An erase/program and a read can be executed concurrently in two banks configuration
• Uses automatic program algorithm (Embedded Algorithm)
• Erase pause/restart function
• Detects completion of writing/erasing using data polling or toggle bit functions
• Detects completion of writing/erasing by CPU interrupts
• Erase function by sector (any combination of sectors)
• Programming/erase available 10,000 (Min.)
• Flash read cycle time (Min.): 2 machine cycles
476
Upper bank
Read
Write/Sector erase
FUJITSU MICROELECTRONICS LIMITED
Lower bank
Read
Write/Sector erase
Read
Chip erase
MB90335 Series
CM44-10137-6E