19.1.2 Mode Programming and Flash Memory Address Space
As its on-chip ROM, the H8/3434F has 32 kbytes of flash memory. The flash memory is
connected to the CPU by a 16-bit data bus. The CPU accesses both byte data and word data in two
states.
The H8/3434F’s flash memory is assigned to addresses H'0000 to H'7FFF. The mode pins enable
either on-chip flash memory or external memory to be selected for this area. Table 19.2
summarizes the mode pin settings and usage of the memory area.
Table 19.2 Mode Pin Settings and Flash Memory Area
Mode Pin Setting
Mode
MD1
0
MD0
0
Memory Area Usage
Illegal setting
Mode 0
Mode 1
Mode
0
1
External memory area
21
0
On-chip
flash
memory
area
Mode 3
1
1
On-chip flash memory area
19.1.3 Features
Features of the flash memory are listed below.
•
Five flash memory operating modes
The flash memory has five operating modes: program mode, program-verify mode, erase
mode, erase-verify mode, and prewrite-verify mode.
•
Block erase designation
Blocks to be erased in the flash memory address space can be selected by bit settings. The
address space includes a large-block area (four blocks with sizes from 4 kbytes to 8 kbytes)
and a small-block area (eight blocks with sizes from 128 bytes to 1 kbyte).
•
Program and erase time
Programming one byte of flash memory typically takes 50 µs. Erasing all blocks (32 kbytes)
typically takes 1 s.
•
•
Erase-program cycles
Flash memory contents can be erased and reprogrammed up to 100 times.
On-board programming modes
These modes can be used to program, erase, and verify flash memory contents. There are two
modes: boot mode and user programming mode.
376
HITACHI [ HITACHI SEMICONDUCTOR ]
