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MPC555
/
MPC556
RESET
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
7-5
7.4 Reset Status Register
All of the reset sources are fed into the reset controller. The 16-bit reset status register
(RSR) reflects the most recent source, or sources, of reset. (Simultaneous reset re-
quests can cause more than one bit to be set at the same time.) This register contains
one bit for each reset source. A bit set to logic one indicates the type of reset that oc-
curred.
Once set, individual bits in the RSR remain set until software clears them. Can be
cleared by writing a one to the bit. A write of zero has no effect on the bit. The register
can be read at all times. The reset status register receives its default reset values dur-
ing power-on reset. The RSR is powered by the KAPWR pin.
RSR
— Reset Status Register
0x2F C288
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
EHRS ESRS
LLRS SWRS CSRS
DB-
HRS
DB-
SRS
JTRS
OCCS
ILBC
GPOR
GH-
RST
GSRS
T
RESERVED
RESET:
0
0
0
0
0
0
0
0
0
0
1
1
1
0
0
0
Table 7-3 Reset Status Register Bit Descriptions
Bit(s)
Name
Description
0
EHRS
1
External hard reset status
0 = No external hard reset has occurred
1 = An external hard reset has occurred
1
ESRS
1
External soft reset status
0 = No external soft reset has occurred
1 = An external soft reset has occurred
2
LLRS
Loss of lock reset status
0 = No enabled loss-of-lock reset has occurred
1 = An enabled loss-of-lock reset has occurred
3
SWRS
Software watchdog reset status
0 = No software watchdog reset has occurred
1 = A software watchdog reset has occurred
4
CSRS
Checkstop reset status
0 = No enabled checkstop reset has occurred
1 = An enabled checkstop reset has occurred
5
DBHRS
Debug port hard reset status
0 = No debug port hard reset request has occurred
1 = A debug port hard reset request has occurred
6
DBSRS
Debug port soft reset status
0 = No debug port soft reset request has occurred
1 = A debug port soft reset request has occurred
7
JTRS
JTAG reset status
0 = No JTAG reset has occurred
1 = A JTAG reset has occurred
8
OCCS
On-chip clock switch
0 = No on-chip clock switch reset has occurred
1 = An on-chip clock switch reset has occurred
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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