Flash Memory Programming/Erasing; Program/Program-Verify - Hitachi H8S/2378, H8S/2378R Series Hardware Manual

20.8

Flash Memory Programming/Erasing

A software method, using the CPU, is employed to program and erase flash memory in the on-
board programming modes. Depending on the FLMCR1 and FLMCR2 setting, the flash memory
operates in one of the following four modes: program mode, erase mode, program-verify mode,
and erase-verify mode. The programming control program in boot mode and the user
program/erase program in user mode use these operating modes in combination to perform
programming/erasing. Flash memory programming and erasing should be performed in
accordance with the descriptions in section 20.8.1, Program/Program-Verify and section 20.8.2,
Erase/Erase-Verify, respectively.
20.8.1

Program/Program-Verify

When programming data or programs to the flash memory, the program/program-verify flowchart
shown in figure 20.9 should be followed. Performing programming operations according to this
flowchart will enable data or programs to be programmed to the flash memory without subjecting
the chip to voltage stress or sacrificing program data reliability.
1. Programming must be done to an empty address. Do not reprogram an address to which
programming has already been performed.
2. Programming should be carried out 128 bytes at a time. A 128-byte data transfer must be
performed even if programming fewer than 128 bytes. In this case, H'FF data must be written
to the extra addresses.
3. Prepare the following data storage areas in RAM: a 128-byte programming data area, a 128-
byte reprogramming data area, and a 128-byte additional-programming data area. Perform
reprogramming data computation and additional programming data computation according to
figure 20.9.
4. Consecutively transfer 128 bytes of data in byte units from the reprogramming data area or
additional-programming data area to the flash memory. The program address and 128-byte
data are latched in the flash memory. The lower 8 bits of the start address in the flash memory
destination area must be H'00 or H'80.
5. The time during which the P bit is set to 1 is the programming time. Figure 20.9 shows the
allowable programming times.
6. The watchdog timer (WDT) is set to prevent overprogramming due to program runaway, etc.
Set a value greater than (y + z2 + α + β) µs as the WDT overflow period.
7. For a dummy write to a verify address, write 1-byte data H'FF to an address whose lower 2
bits are B'00. Verify data can be read in words from the address to which a dummy write was
performed.
8. The maximum number of repetitions of the program/program-verify sequence to the same bit
(N) must not be exceeded.
Rev. 1.0, 09/01, page 784 of 904