HD64F2357F20V Datasheet, PDF (645/1049 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-chip Microcomputer H8S Family / H8S/2300 Series

• In user program mode, FWE can be switched between high and low level regardless of the reset state. FWE input can
also be switched during program execution in flash memory.
• Do not apply FWE if program runaway has occurred.
• Disconnect FWE only when the SWE, ESU, PSU, EV, PV, P, and E bits in FLMCR1 and FLMCR2 are cleared.
• 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 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 program execution in flash memory: Clear 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 flash
memory should only be accessed for verify operations (verification during programming/erasing). 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 32-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.
Rev.6.00 Oct.28.2004 page 615 of 1016
REJ09B0138-0600H