HD64F3039F18 Datasheet, PDF (513/710 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8 Family / H8/300H Series

Section 15 ROM
(2) Notes on powering on/powering off (See figures 15.25 to 15.27.)
Input a high level to the FWE pin after verifying Vcc. Before turning off Vcc, set the FWE pin
to a low level.
When powering on and powering off the Vcc power supply, fix the FWE pin a low level and
set the flash memory to the hardware protection mode.
Be sure that the powering on and powering off timing is satisfied even when the power is
turned off and back on in the event of a power interruption, etc. If this timing is not satisfied,
microcomputer runaway, etc., may cause overprogramming or overerasing and the memory
cells may not operate normally.
(3) Notes on FWE pin High/Low switching (See figures 15.25 to 15.27.)
Input FWE in the state microcomputer operation is verified. If the microcomputer does not
satisfy the operation confirmation state, fix the FWE pin at a low level to set the protection
mode.
To prevent erroneous programming/erasing of flash memory, note the following in FWE pin
High/Low switching:
• Apply an input to the FWE pin after the Vcc voltage has stabilized within the rated voltage.
If an input is applied to the FWE pin when the microcomputer Vcc voltage does not satisfy
the rated voltage, flash memory may be erroneously programmed or erased because the
microcomputer is in the unconfirmed state.
• Apply an input to the FWE pin when the oscillation has stabilized (after the oscillation
stabilization time).
When turning on the Vcc power, apply an input to the FWE pin after holding the RES pin
at a low level during the oscillation stabilization time (t_osc1=20ms). Do not apply an input to
the FWE pin when oscillation is stopped or unstable.
• In the boot mode, perform FWE pin High/Low switching during reset.
In transition to the boot mode, input FWE = High level and set MD₂ to MD₀ while the RES
input is low. At this time, the FWE and MD₂ to MD₀ inputs must satisfy the mode
programming setup time (t_MDS) relative to the reset clear timing. The mode programming
setup time is necessary for RES reset timing even in transition from the boot mode to
another mode.
In reset during operation, the RES pin must be held at a low level for at least 20 system
clocks.
• In the user program mode, FWE = High/Low switching is possible regardless of the RES
input.
FWE input switching is also possible during program execution on flash memory.
Rev.3.00 Mar. 26, 2007 Page 489 of 682
REJ09B0353-0300