NEC V850/SC1, V850/SC2, V850/SC3 CHAPTER 4 CAUTIONS 4.1 VDD and PORTVDD of Target System

User’s Manual U15776EJ1V0UM
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CHAPTER 4 CAUTIONS
4.1 VDD and PORTVDD of Target System
(1) VDD in the target system is used to sense the level for target system power supply ON/OFF.
• When VDD is lower than 3.5 V, it is judged that the target system is not connected, and mapping of the
target memory cannot be performed with a debugger (FCAN cannot be used).
• When VDD is 3.5 V or higher, it is judged that the target system is connected, and mapping of the target
memory can be performed with a debugger (FCAN can be used).
(2) PORTVDDn (n = 0 to 2) in the target system is not supplied directly to the emulator chip; it is connected to the
target voltage emulation circuit.
• When PORTVDDn is lower than 3.3 V, VCC (5 V) in the internal emulator is supplied to the emulator chip.
• When PORTVDDn is 3.3 V or higher, a voltage of the same potential as PORTVDDn in the target system is
generated and supplied to the emulator chip.
Figure 4-1. Schematic Diagram of Power Supply Acquisition
Relay n
(n = 0 to 2)
V850/SC3
I/O chip
Target voltage emulation n
(n = 0 to 2)
ON/OFF?
V CC (5 V)
PORTV
DDn
(n = 0 to 2)
V
DD0
IE-703089-MC-EM1 IE-703002-MC
Relay
Target voltage
emulation
V CC (5 V)
Evaluation
chip
Target system