HD64F7051SFJ20V Datasheet, PDF (581/843 Pages) Renesas Technology Corp – Hardware Manual Renesas 32-Bit RISC

Section 18 ROM (128 kB Version)
18.7.3 Erase Mode
To perform data or program erasure, set the 1 bit flash memory area to be erased in erase block
register 1 (EBR1) at least 10 µs after setting the SWE bit to 1 in flash memory control register 1
(FLMCR1). Next, the watchdog timer is set to prevent overerasing in the event of program
runaway, etc. Set 6.6 ms as the WDT overflow period. After this, preparation for erase mode
(erase setup) is carried out by setting the ESU bit in FLMCR1, and after the elapse of 200 µs or
more, the operating mode is switched to erase mode by setting the E bit in FLMCR1. The time
during which the E bit is set is the flash memory erase time. Ensure that the erase time does not
exceed 5 ms.
Note: With flash memory erasing, preprogramming (setting all memory data in the memory to
be erased to all “0”) is not necessary before starting the erase procedure.
18.7.4 Erase-Verify Mode
In erase-verify mode, data is read after memory has been erased to check whether it has been
correctly erased.
After the elapse of the erase time, erase mode is exited (the E bit in FLMCR1 is cleared, then the
ESU bit is cleared at least 10 µs later), the watchdog timer is cleared after the elapse of 10 µs or
more, and the operating mode is switched to erase-verify mode by setting the EV bit in FLMCR1.
Before reading in erase-verify mode, a dummy write of H'FF data should be made to the addresses
to be read. The dummy write should be executed after the elapse of 20 µs or more. When the flash
memory is read in this state (verify data is read in 32-bit units), the data at the latched address is
read. Wait at least 2 µs after the dummy write before performing this read operation. If the read
data has been erased (all “1”), a dummy write is performed to the next address, and erase-verify is
performed. If the read data has not been erased, set erase mode again, and repeat the erase/erase-
verify sequence in the same way. However, ensure that the erase/erase-verify sequence is not
repeated more than 60 times. When verification is completed, exit erase-verify mode, and wait for
at least 5 µs. If erasure has been completed on all the erase blocks, clear the SWE bit in FLMCR1.
If there are any unerased blocks, set 1 bit for the flash memory area to be erased, and repeat the
erase/erase-verify sequence in the same way.
Rev. 5.00 Jan 06, 2006 page 559 of 818
REJ09B0273-0500