CHAPTER 5 INITIALIZATION INTERFACE
User’s Manual U14272EJ3V0UM
105
5.3.2 Soft Reset
Caution
Soft Reset is not supported in the current V
R
4181.
A Soft Reset initializes the CPU core without affecting the output clocks; in other words, a Soft Reset is a logical
reset. In a Soft Reset, the CPU core retains as much state information as possible; all state information except for the
following is retained:
•
The TS bit of the Status register is cleared to 0.
•
The SR, ERL and BEV bits of the Status register are set to 1.
•
The IP7 bit of the Cause register is cleared to 0.
•
Any interrupts generated on the SysAD bus are cleared.
•
NMI is cleared.
•
The Config register is initialized.
A Soft Reset is started by assertion of the Reset# signal, and is completed at the deassertion of the Reset# signal
synchronized with the rising edge of MasterOut. In general, data in the CPU core is preserved for debugging
purpose.
Upon reset, the CPU core becomes bus master and drives the SysAD bus (internal). After Reset# is deasserted,
the CPU core branches to the Reset exception vector and begins executing the reset exception code.
Figure 5-9. Soft Reset
Reset# (Internal)
MasterClock
Note
(Internal)
V
DD
TClock (Internal)
MasterOut (Internal)
H
Note MasterClock is the basic clock used in the CPU core. Its frequency is one forth of TClock frequency.