R8C25 Datasheet, PDF (493/525 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MCU R8C FAMILY / R8C/2x SERIES

R8C/24 Group, R8C/25 Group
21. Usage Notes
21.8 Notes on Flash Memory
21.8.1 CPU Rewrite Mode
21.8.1.1 Operating Speed
Before entering CPU rewrite mode (EW0 mode), select 5 MHz or below for the CPU clock using the CM06 bit
in the CM0 register and bits CM16 to CM17 in the CM1 register. This does not apply to EW1 mode.
21.8.1.2 Prohibited Instructions
The following instructions cannot be used in EW0 mode because they reference data in the flash memory:
UND, INTO, and BRK.
21.8.1.3 Interrupts
Table 21.2 lists the EW0 Mode Interrupts, and Table 21.3 lists the EW1 Mode Interrupts.
Table 21.2 EW0 Mode Interrupts
Mode
Status
When Maskable Interrupt
Request is Acknowledged
EW0 During auto-erasure Any interrupt can be used by
allocating a vector in RAM
Auto-programming
When Watchdog Timer, Oscillation
Stop Detection, Voltage Monitor 1, or
Voltage Monitor 2 Interrupt Request is
Acknowledged
Once an interrupt request is
acknowledged, auto-programming or
auto-erasure is forcibly stopped
immediately and the flash memory is
reset. Interrupt handling starts after the
fixed period and the flash memory
restarts. Since the block during auto-
erasure or the address during auto-
programming is forcibly stopped, the
normal value may not be read. Execute
auto-erasure again and ensure it
completes normally.
Since the watchdog timer does not stop
during the command operation,
interrupt requests may be generated.
Reset the watchdog timer regularly.
NOTES:
1. Do not use the address match interrupt while a command is being executed because the vector of
the address match interrupt is allocated in ROM.
2. Do not use a non-maskable interrupt while block 0 is being automatically erased because the fixed
vector is allocated in block 0.
Rev.3.00 Feb 29, 2008 Page 476 of 485
REJ09B0244-0300