R8C/20 Group, R8C/21 Group 19. Flash Memory
Rev.2.00 Aug 27, 2008 Page 383 of 458
REJ09B0250-0200
19.4.1 EW0 Mode
The MCU enters CPU rewrite mode and software commands can be acknowledged by setting the FMR01 bit in
the FMR0 register to 1 (CPU rewrite mode enabled). In this case, since the FMR11 bit in the FMR1 register is
set to 0, EW0 mode is selected.
Use software commands to control a program and erase operations. The FMR0 register or the status register can
determine status when program and erase operation complete.
When entering an erase-suspend, set the FMR40 bit to 1 (enables suspend) and the FMR41 bit to 1 (requests
erase-suspend). Wait for td(SR-SUS) and ensure that the FMR46 bit is set to 1 (enables reading) before
accessing the user ROM area. The auto-erase operation restarts by setting the FMR41 bit to 0 (erase restarts).
When entering a program-suspend during the auto-program, set the FMR40 bit to 1 (enables suspend) and the
FMR42 bit to 1 (requests program-suspend). Wait for td(SR-SUS) and ensure that the FMR46 bit is set to 1
(enables reading) before accessing the user ROM area. The auto-program operation restarts by setting the
FMR42 bit to 0 (program restarts).
19.4.2 EW1 Mode
The MCU enters EW1 mode by setting the FMR11 bit to 1 (EW1 mode) after setting the FMR01 bit to 1 (CPU
rewrite mode enabled).
The FMR0 register can determine status when program and erase operation complete. Do not execute
commands of the read status register in EW1 mode.
To enable the erase-suspend function during the auto-erase, execute the block erase command after setting the
FMR40 bit to 1 (enables suspend). The interrupt to enter an erase-suspend should be in interrupt enabled status.
After passing td(SR-SUS) since the block erase command is executed, an interrupt request is acknowledged.
When an interrupt request is generated, the FMR41 bit is automatically set to 1 (requests erase-suspend) and the
auto-erase operation is halted. If the auto-erase operation does not complete (FMR00 bit is 0) when the interrupt
process completes, the auto-erase operation restarts by setting the FMR41 bit to 0 (erase restarts)
To enable the program-suspend function during the auto-program, execute the program command after setting
the FMR40 bit to 1 (enables suspend). The interrupt to enter a program-suspend should be in interrupt enabled
status. After waiting for td(SR-SUS) since the program command is executed, an interrupt request is
acknowledged.
When an interrupt request is generated, the FMR42 bit is automatically set to 1 (requests program-suspend) and
the auto-program operation suspends. When the auto-program operation does not complete (FMR00 bit is 0)
after the interrupt process completes, the auto-program operation restarts by setting the FMR42 bit to 0
(program restarts).
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