HD64F3048VTF8 Datasheet, PDF (643/903 Pages) Renesas Technology Corp – Hardware Manual Renesas 8-Bit Single-Chip

Section 18 ROM (H8/3048F-ONE: Single Power Supply, H8/3048B Mask ROM Version)
18.9 Flash Memory Emulation in RAM
As flash memory programming and erasing takes time, it may be difficult to carry out tuning by
writing parameters and other data in real time. In this case, real-time programming of flash
memory can be emulated by overlapping part of RAM (H'FFF000–H'FFF3FF) onto a small block
area in flash memory. This RAM area change is executed by means of bits 3 to 1 in the RAM
control register (RAMCR). After the RAM area change, access is possible both from the area
overlapped onto flash memory and from the original area (H'FFF000–H'FFF3FF). For details of
RAMCR and the RAM area setting method, see section 18.5.4, RAM Control Register (RAMCR).
Example of Emulation of Real-Time Flash Memory Programming
In the following example, RAM area H'FFF000–H'FFF3FF is overlapped onto flash memory area
EB2 (H'000800–H'000BFF).
H'000000
Block area
Flash memory
space
EB2 ^H'000800
area _H'000BFF
H'000FFF
Overlapping RAM
(Mapping RAM
*
area)
H'FFEF10
On-chip RAM
area
H'FFEFFF
H'FFF000
H'FFF3FF
H'FFF400
H'FFFF0F
(Actual RAM
area)
Procedure:
1. Part of RAM (H'FFF000−
H'FFF3FF) is overlapped onto the
area (EB2) requiring real-time
programming.
(RAMCR bits 3−1 are set to 1, 1, 0,
and the flash memory area to be
overlapped (EB2) is selected.)
2. Real-time programming is
performed using the overlapping
RAM.
3. The programmed data is checked,
then RAM overlapping is cleared.
(RAMS bit is cleared.)
4. The data written in RAM area
H'FFF000−H'FFF3FF is written to
flash memory space.
Note: * When part of RAM (H'FFF000−H'FFF3FF) is overlapped onto a flash memory small block area, the flash
memory in the overlapped area cannot be accessed. It can be accessed when the overlapping is
cleared.
Figure 18.16 Example of RAM Overlap Operation
Rev. 3.00 Sep 27, 2006 page 615 of 872
REJ09B0325-0300