Renesas H8S/2318 series, Hardware Manual

Page: 638 / 1121

Rev. 5.00, 12/03, page 608 of 1088
Make sure that the SWE, ESU, PSU, EV, PV, P, and E bits are not set by mistake when
applying or disconnecting FWE.
Do not apply a constant high level to the FWE pin: Apply a high level to the FWE pin only
when programming or erasing flash memory. A system configuration in which a high level is
constantly applied to the FWE pin should be avoided. Also, while a high level is applied to the
FWE pin, the watchdog timer should be activated to prevent overprogramming or overerasing due
to program runaway, etc.
Use the recommended algorithm when programming and erasing flash memory: The
recommended algorithm enables programming and erasing to be carried out without subjecting the
device to voltage stress or sacrificing program data reliability. When setting the P or E bit in
FLMCR1, the watchdog timer should be set beforehand as a precaution against program runaway,
etc.
Do not set or clear the SWE bit during execution of a program in flash memory: Wait for at
least 100
µ
s after clearing the SWE bit before executing a program or reading data in flash
memory. When the SWE bit is set, data in flash memory can be rewritten, but when SWE = 1,
flash memory can only be read in program-verify or erase-verify mode. Access flash memory only
for verify operations (verification during programming/erasing). Also, do not clear the SWE bit
during programming, erasing, or verifying.
Similarly, when using the RAM emulation function while a high level is being input to the FWE
pin, the SWE bit must be cleared before executing a program or reading data in flash memory.
However, the RAM area overlapping flash memory space can be read and written to regardless of
whether the SWE bit is set or cleared.
Do not use interrupts while flash memory is being programmed or erased: All interrupt
requests, including NMI, should be disabled during FWE application to give priority to
program/erase operations.
Do not perform additional programming. Erase the memory before reprogramming: In on-
board programming, perform only one programming operation on a 128-byte programming unit
block. In PROM mode, too, perform only one programming operation on a 128-byte programming
unit block. Programming should be carried out with the entire programming unit block erased.
Before programming, check that the chip is correctly mounted in the PROM programmer:
Overcurrent damage to the device can result if the index marks on the PROM programmer socket,
socket adapter, and chip are not correctly aligned.
Do not touch the socket adapter or chip during programming: Touching either of these can
cause contact faults and write errors.