Datasheet

Section 7 ROM
REJ09B0465-0300 Rev. 3.00 Page 159 of 982
Sep 17, 2010
H8S/20103, H8S/20203, H8S/20223, H8S/20115, H8S/20215, H8S/20235 Group
7.3 CPU Reprogramming Mode
In CPU reprogramming mode, the user ROM area can be reprogrammed by executing the software
commands by the CPU. The software commands should be issued to the specific area to be
reprogrammed in the user ROM area.
If an interrupt is requested during erasure operation in CPU reprogramming mode, erasure can be
suspended to process the interrupt. This is referred to as erase-suspend function. In erase-suspend
mode, the user ROM area can be read through programming.
The CPU has two reprogramming modes, EW0 mode and EW1 mode. Table 7.1 shows
differences between the two modes.
Table 7.1 Differences between EW0 Mode and EW1 Mode
Item EW0 Mode EW1 Mode
Area in which a reprogramming-
control program can be located
User ROM area User ROM area
Area in which a reprogramming-
control program can be
executed
A reprogramming-control
program must be transferred to
RAM before execution.
A reprogramming-control
program can be executed in the
user ROM area.
Area which can be
reprogrammed
User ROM area User ROM area excluding the
blocks in which a
reprogramming-control program
is located.
Limitations on software
commands
None The program and erasure
commands must not be
executed on any block in which
a reprogramming-control
program is located.
Mode after software command
execution
Read-array mode Read-array mode