upd70f3402 Renesas Electronics Corporation., upd70f3402 Datasheet - Page 72

• Manufacturer Part Number: upd70f3402
• Description: 32-/16-bit Single-chip Microcontroller With Can Interface
• Manufacturer: Renesas Electronics Corporation.

(2)
PRCMD
Remark:
Caution:
72
Symbol
R/W
Command register (PRCMD)
The command register (PRCMD) is an 8-bit register that protects the registers that may seriously
affect the application system from being written, so that the system does not inadvertently stop
due to a program hang-up. The first write access to a special register (power save control register
(PSC)) is valid after data has been written in advance to the PRCMD register. In this way, the value
of the special register can be rewritten only in a specific sequence, so as to protect the register
from an illegal write access.
PRCMD register must be written with store instruction execution by CPU only (not with DMA trans-
fer). If an illegal store operation to a special register takes place, it can be checked by the PERR
flag of the system status register (SYS).
The PRCMD register is write-only, in 8-bit units (undefined data is read when this register is read).
W
PRCMD, PSC, MPCCTL, CKC, PCC, CLM, RESF, LVIM, RAMS, OCDM registers must
Registration Code is any 8-bit data.
be written with store instruction execution by CPU only. If an illegal store operation to
a special register takes place, it can be checked by the PERR flag of the system sta-
tus register (SYS).
7
W
6
Figure 3-10: Command Register (PRCMD) Format
W
5
8 bits Registration Code
User’s Manual U16702EE3V2UD00
Chapter 3 CPU Function
W
4
W
3
W
2
W
1
W
0
FFFFF1FCH
Address
After reset
undefined