h8s-2649 Renesas Electronics Corporation., h8s-2649 Datasheet - Page 595

• Manufacturer Part Number: h8s-2649
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

Section 19 ROM
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 µs 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. 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 programmer 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.
Reset the flash memory before turning on the power: To reset the flash memory during
oscillation stabilization period, the reset signal must be input for at least 100 µs.
Apply the reset signal while SWE is low to reset the flash memory during its operation: The
reset signal is applied at least 100 µs after the SWE bit has been cleared.
Rev. 2.00 Dec. 05, 2005 Page 557 of 724
REJ09B0200-0200