17.18.2 Ram Overlap - Renesas H8S/2319 series Hardware Manual

17.18.2 RAM Overlap

An example in which flash memory block area EB1 is overlapped is shown below.
H'000000
H'001000
H'002000
H'030000
H'004000
H'005000
H'006000
H'007000
H'008000
H'07FFFF
Example in Which Flash Memory Block Area EB1 is Overlapped
1. Set bits RAMS, RAM2, RAM1, and RAM0 in RAMER to 1, 0, 0, 1, to overlap part of RAM
onto the area (EB1) for which real-time programming is required.
2. Real-time programming is performed using the overlapping RAM.
3. After the program data has been confirmed, the RAMS bit is cleared, releasing RAM overlap.
4. The data written in the overlapping RAM is written into the flash memory space (EB1).
Notes: 1. When the RAMS bit is set to 1, program/erase protection is enabled for all blocks
regardless of the value of RAM2, RAM1, and RAM0 (emulation protection). In this
state, setting the P1 or E1 bit in flash memory control register 1 (FLMCR1), or setting
the P2 or E2 bit in FLMCR2 will not cause a transition to program mode or erase
mode. When actually programming a flash memory area, the RAMS bit should be
cleared to 0.
Rev. 5.00, 12/03, page 648 of 1088
EB0
EB1
EB2
EB3
EB4
EB5
EB6
EB7
Flash memory
EB8 to EB15
Figure 17-49 Example of RAM Overlap Operation
This area can be accessed
from both the RAM area
and flash memory area
On-chip RAM
H'FFDC00
H'FFEBFF
H'FFFBFF