MC9S12DP256B Datasheet, PDF (58/126 Pages) Freescale Semiconductor, Inc – device made up of standard HCS12 blocks and the HCS12 processor core

MC9S12DP256B Device User G^Fui^rd^ee^e—^scV0^a2.^l1^e5 ^{Semiconductor, Inc.}
2.3.2 RESET — External Reset Pin
An active low bidirectional control signal, it acts as an input to initialize the MCU to a known start-up
state, and an output when an internal MCU function causes a reset.
2.3.3 TEST — Test Pin
This input only pin is reserved for test.
NOTE: The TEST pin must be tied to VSS in all applications.
2.3.4 VREGEN — Voltage Regulator Enable Pin
This input only pin enables or disables the on-chip voltage regulator.
2.3.5 XFC — PLL Loop Filter Pin
PLL loop filter. Please ask your Motorola representative for the interactive application note to compute
PLL loop filter elements. Any current leakage on this pin must be avoided.
XFC
MCU
R₀
C_S
VDDPLL
C_P
VDDPLL
Figure 2-4 PLL Loop Filter Connections
2.3.6 BKGD / TAGHI / MODC — Background Debug, Tag High, and Mode Pin
The BKGD/TAGHI/MODC pin is used as a pseudo-open-drain pin for the background debug
communication. In MCU expanded modes of operation when instruction tagging is on, an input low on
this pin during the falling edge of E-clock tags the high half of the instruction word being read into the
instruction queue. It is used as a MCU operating mode select pin during reset. The state of this pin is
latched to the MODC bit at the rising edge of RESET.
2.3.7 PAD15 / AN15 / ETRIG1 — Port AD Input Pin of ATD1
PAD15 is a general purpose input pin and analog input AN7 of the analog to digital converter ATD1. It
can act as an external trigger input for the ATD1.
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