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User’s Manual U11969EJ3V0UM00
CHAPTER 3 CPU FUNCTIONS
3.3 Operation Modes
3.3.1 Operation modes
The V854 has the following operations modes. These modes are selected by the MODE pin (n = 0 to 2).
(1) Normal operation modes
(a) Single-chip mode (
µ
PD703008, 70F3008, 703008Y, 70F3008Y only)
After the system has been released from the reset status, the pins related to the bus interface are set
for port mode, execution branches to the reset entry address of the internal ROM, and instruction
processing is started. However, access to external memory and peripheral devices can be enabled by
setting in the external memory expansion mode register by instruction (MM: refer to 3.4.6 (1)).
CLKOUT signal output is disabled when reset in the single-chip mode 1. However, it is input in the single-
chip mode 2.
(b) ROM-less mode
After the system has been released from the reset status, the pins related to bus interface are set for control
mode, execution branches to the reset address of external memory, and instruction processing is started.
Instruction fetch and data access to internal ROM are disabled.
UBEN, LBEN, R/W, and DSTB signal are output when reset in the ROM-less mode. UBEN, WRL, WRH,
and RD signal are output in the ROM-less mode 2.
(2) Flash memory programming mode (
µ
PD70F3008, 70F3008Y only)
This mode is provided only to on-chip flash memory model. If flash memory write voltage (7.8 V) is input to
V
PP
pin, the program operation to internal flash memory by flash writer is possible.
3.3.2 Specifying operation mode
The operation mode of the V854 is specified depending on the status of the MODE pin. Set these pins in the
application system (n = 0 to 2).
If the setting is changed during operation, the operation is not guaranteed.
(a)
µ
PD703006
MODE2
MODE1
MODE0
Operation Mode
0
0
1
ROM-less mode 1
0
0
1
ROM-less mode 2
Other than above
Setting prohibited
(b)
µ
PD703008, 703008Y
MODE2
MODE1
MODE0
Operation Mode
0
0
0
ROM-less mode 1
0
0
1
ROM-less mode 2
0
1
0
Single-chip mode 1
0
1
1
Single-chip mode 2
Other than above
Setting prohibited
Normal operation
mode
Normal operation
mode
Содержание V854 UPD703006
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