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ERTEC 200P-2 Manual
Technical data subject to change
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2.3.9.4.4 Asynchronous ARM926 Watchdog Reset
The ARM926 watchdog reset is hardware monitoring of the software on the ARM926EJ-
S. The basis for monitoring is a time set in the watchdog timer. This time starts to run
when the watchdog is activated. If the timer is not retriggered to its initial value during this
time, a watchdog reset (XRES_ARM926_WD) is triggered (output ARM926 watchdog:
WD_XWDOUT1). If the watchdog function is enabled (WD_RES_FREI_ ARM926) (see
ASYN_RES_CTRL_REG in 2.3.10.9.22
), ERTEC 200P is reset. The actual reset signal is
connected with configurable pulse generation . The ARM926_WDOG_RES bit in
RES_STAT_REG is set during an ARM926 watchdog reset to allow an analysis of the
reset event after a system restart. This bit is not affected by the reset function triggered.
Upon restart, the software can read RES_STAT_REG (see 2.3.10.9.22
X
).
If, in a given application, you do not want expiry of the watchdog time to affect the opera-
tion of the PN-IP, you can exclude the PN-IP from the watchdog reset (EN_WD_RES_PN
= 0 im ASYN_RES_CTRL_REG).
Important: The EN_WD_RES_PN bit is always set (
PNIP subject to ARM926 watch-
dog reset) if the PNIP is reset.
If an asynchronous software reset is to be generated by
the SW for the PN-IP (see 2.3.9.4.6), the SW must if necessary then set '
EN_WD_RES_PN = 0' again if you do not want a PN-IP reset at the end of the ARM926
watchdog time.
Before the watchdog expires, an interrupt is generated for the ARM926
'WD_INT_ARM926' (see 2.3.2.14) and the preliminary event 'WD_XWDOUT0' is signaled
to the external host over a GPIO pin.
The watchdog also runs when the clock source fails (e.g. quartz break). In this case, the
PLL then switches to its free-running frequency (100 – 300 MHz).
When booting after a watchdog reset, the system uses the boot mode latched internally
during PowerOn reset.
2.3.9.4.5 Asynchronous Software Reset for ERTEC 200P (Without PN-IP)
In the ERTEC 200P, an asynchronous software reset can be triggered by setting the
'RES_SOFT' bit in RES_CRTL_REG (in SCRB, see 2.3.10.9.22); the PN-IP and PHYs
are not reset. The SW_RES bit in RES_STAT_REG is set during an asynchronous soft-
ware reset to allow an analysis of the reset event after a system restart. This bit is not
affected by the reset function triggered. Upon restart, the software can read
RES_STAT_REG (see 2.3.10.9.22).
When booting after a software reset, the system uses the boot mode latched internally
during PowerOn reset.
2.3.9.4.6 Asynchronous Software Reset for PN-IP
The PN-IP and PHYs can only be reset asynchronously by the software with the
'RES_SOFT_PN' bit in the SCRB register 'ASYN_RES_CTRL_REG' (see 2.3.10.9.22).
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