CHAPTER 3 CPU FUNCTION
55
User’s Manual U15195EJ5V0UD
3.3 Operation
Modes
3.3.1
Operation modes
The V850E/IA2 has the following operation modes. Mode specification is carried out by the MODE0 and MODE1
pins.
(1) Normal operation mode
(a) Single-chip mode
Access to the internal ROM is enabled.
In single-chip mode, after the system reset is cleared, each pin related to the bus interface enters the port
mode, program execution branches to the reset entry address of the internal ROM, and instruction
processing starts. By setting the PMCDH, PMCDL, PMCCT, and PMCCM registers to control mode by
instruction, an external device can be connected to the external memory area.
(b) ROMless mode
After the system reset is cleared, each pin related to the bus interface enters the control mode, program
execution branches to the external device’s (memory) reset entry address, and instruction processing
starts. Fetching of instructions and data access for internal ROM becomes impossible.
In ROMless mode, the data bus is a 16-bit data bus.
(2) Flash memory programming mode (
µ
PD70F3114 only)
If this mode is specified, it becomes possible for the flash programmer to run a program to the internal flash
memory.
The initial values of the registers differ depending on the mode.
Operation Mode
PMCDH
PMCDL
PMCCT
PMCCM
BSC
ROMless mode
FFH FFFFH 53H 03H 5555H
Normal
operation
mode
Single-chip mode
00H 0000H 00H 00H 5555H