HD64F3337YCP16V Datasheet, PDF (488/749 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

PVOK:
NGEND:
CMP.B
BEQ
ADD.W
BRA
#H'32,
NGEND
R5,
PRGMS
BCLR
MOV.B
MOV.B
#2,
#H'00,
R6L,
One byte programmed
Programming error
R6L
R5
; Program-verify executed 6 times?
; If program-verify executed 6 times, branch to NGEND
; Programming time × 2
; Program again
@FLMCR:8 ; Clear PV bit
R6L ;
@EBR*:8 ; Clear EBR*
20.4.4 Erase Mode
To erase the flash memory, follow the erasing algorithm shown in figure 20.9. This erasing
algorithm can erase data without subjecting the device to voltage stress or impairing the reliability
of programmed data.
To erase flash memory, before starting to erase, first place all memory data in all blocks to be
erased in the programmed state (program all memory data to H'00). If all memory data is not in the
programmed state, follow the sequence described later to program the memory data to zero. Select
the flash memory areas to be erased with erase block registers 1 and 2 (EBR1 and EBR2). Next set
the E bit in FLMCR, selecting erase mode. The erase time is the time during which the E bit is set.
To prevent overerasing, To prevent overerasing, use a software timer to divide the time for a
single erase, and ensure that the total time does not exceed 30 seconds. For the time for a single
erase, refer to section 20.4.6, Erase Flowchart and Sample Programs. Overerasing, due to program
runaway for example, can give memory cells a negative threshold voltage and cause them to
operate incorrectly. Before selecting erase mode, set up the watchdog timer so as to prevent
overerasing.
20.4.5 Erase-Verify Mode
In erase-verify mode, after data has been erased, it is read to check that it has been erased
correctly. After the erase time has elapsed, exit erase mode (clear the E bit to 0) and select erase-
verify mode (set the EV bit to 1). Before reading data in erase-verify mode, write H'FF dummy
data to the address to be read. This dummy write applies an erase-verify voltage to the memory
cells at the latched address. If the flash memory is read in this state, the data at the latched address
will be read. After the dummy write, wait 2 µs or more before reading. When performing the
initial dummy write, wait 4 µs or more after selecting erase-verify mode. If the read data has been
successfully erased, perform an erase-verify (dummy write, wait 2 µs or more, then read) for the
next address. If the read data has not been erased, select erase mode again and repeat the same
erase and erase-verify sequence through the last address. Do not repeat the erase and erase-verify
sequence more than 602 times, however.
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