upd78f0103hmca1-5a4-a Renesas Electronics Corporation., upd78f0103hmca1-5a4-a Datasheet - Page 351

• Manufacturer Part Number: upd78f0103hmca1-5a4-a
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

(2) Flash protect command register (PFCMD)
(3) Flash status register (PFS)
If the application system stops inadvertently due to malfunction caused by noise or program hang-up, an
operation to write the flash programming mode control register (FLPMC) may have a serious effect on the system.
PFCMD is used to protect FLPMC from being written, so that the application system does not stop inadvertently.
Writing FLPMC is enabled only when a write operation is performed in the following specific sequence.
<1> Write a specific value to PFCMD (PFCMD = A5H)
<2> Write the value to be set to FLPMC (writing in this step is invalid)
<3> Write the inverted value of the value to be set to FLPMC (writing in this step is invalid)
<4> Write the value to be set to FLPMC (writing in this step is valid)
This rewrites the value of the register, so that the register cannot be written illegally.
Occurrence of an illegal store operation can be checked by bit 0 (FPRERR) of the flash status register (PFS).
A5H must be written to PFCMD each time the value of FLPMC is changed.
PFCMD can be set by an 8-bit memory manipulation instruction.
RESET input makes this register undefined.
If data is not written to the flash programming mode control register (FLPMC), which is protected, in the correct
sequence (writing the flash protect command register (PFCMD)), FLPMC is not written and a protection error
occurs. If this happens, bit 0 of PFS (FPRERR) is set to 1.
This bit is a cumulative flag. After checking FPRERR, clear it by writing 0 to it.
PFS can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input clears this register to 00H.
Address: FFC0H
Address: FFC2H
PFCMD
Symbol
Symbol
PFS
Figure 21-19. Format of Flash Protect Command Register (PFCMD)
REG7
0
Figure 21-20. Format of Flash Status Register (PFS)
After reset: Undefined
After reset: 00H
REG6
0
CHAPTER 21 FLASH MEMORY
User’s Manual U16846EJ3V0UD
REG5
0
R/W
REG4
0
W
REG3
0
REG2
0
REG1
0
FPRERR
REG0
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