Flash Memory Programming And Erasing Precautions - Hitachi H8S/2338 Series Hardware Manual

17.12

Flash Memory Programming and Erasing Precautions

Precautions concerning the use of on-board programming mode, the RAM emulation function, and
PROM mode are summarized below.
Use the specified voltages and timing for programming and erasing: Applied voltages in
excess of the rating can permanently damage the device. Use a PROM programmer that supports
the Hitachi microcomputer device type with 256-kbyte on-chip flash memory (FZTAT256V3A).
Do not select the HN27C4096 setting for the PROM programmer, and only use the specified
socket adapter. Failure to observe these points may result in damage to the device.
Powering on and off (see figures 17-30 to 17-32): Do not apply a high level to the FWE pin until
V has stabilized. Also, drive the FWE pin low before turning off V
CC
When applying or disconnecting V
the hardware protection state.
The power-on and power-off timing requirements should also be satisfied in the event of a power
failure and subsequent recovery.
FWE application/disconnection (see figures 17-30 to 17-32): FWE application should be carried
out when MCU operation is in a stable condition. If MCU operation is not stable, fix the FWE pin
low and set the protection state.
The following points must be observed concerning FWE application and disconnection to prevent
unintentional programming or erasing of flash memory:
• Apply FWE when the V
Apply FWE when oscillation has stabilized (after the elapse of the oscillation stabilization
time).
• In boot mode, apply and disconnect FWE during a reset.
• 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 execution of a program 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 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.
power, fix the FWE pin low and place the flash memory in
CC
voltage has stabilized within its rated voltage range.
CC
.
CC
593