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Resets
4.7.3
Reset weak pull up/down configuration
The signal on the WKPCFG pin determines whether specified eTPU and eMIOS pins are connected to
weak pull up or weak pull down devices at reset (see the Signal Description chapter for the eTPU and
eMIOS pins that are affected by WKPCFG). For all reset sources except the Software External Reset, the
WKPCFG pin is applied at the assertion of the internal reset signal (assertion of RSTOUT). If the
WKPCFG signal is logic high at this time, pull up devices will be enabled on the eTPU and eMIOS pins.
If the WKPCFG signal is logic low at the assertion of the internal reset signal, pull down devices will be
enabled on those pins. The value on WKPCFG must be held constant during reset to avoid oscillations on
the eTPU and eMIOS pins caused by switching pull up/down states. The final value of WKPCFG is
latched four clock cycles before the negation of RSTOUT. After reset, software may modify the weak pull
up/down selection for all I/O pins through the PCR registers in the SIU.
MPC5644A Microcontroller Reference Manual, Rev. 6
104
Freescale Semiconductor
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