MC912D60ACPVE8 Datasheet, PDF (357/460 Pages) Freescale Semiconductor, Inc – MC68HC912D60A MC68HC912D60C MC68HC912D60P Technical Data

Analog-to-Digital Converter
General Purpose Digital Input Port Operation
The ATD module reset function places the module back into an
initialized state. If the module is performing a conversion sequence, both
the current conversion and the sequence are terminated. The
conversion complete flags are cleared and any pending interrupts are
cancelled. Note that the control, test, and status registers are initialized
on reset; the initialized register state is defined in the register description
section of this specification.
Note that when the module powers up via a WAIT signal that the ATD is
not reset; ATD operation proceeds as it was prior to entering the wait.
Freezing the module does not cause it to be reset. If a freeze mode is
entered and defines that the current conversion be terminated, then this
is done and the module will be idle after exiting the freeze state, but the
module is not initialized.
Powering the module up (using the ADPU bit) does not cause the
module to reset since the register file is not initialized. Finally, writing to
control register ATDCTL4/5 does not cause the module to be reset; the
current conversion and sequence will be terminated and new ones
started; the conversion complete flags and pending interrupts will be
cleared. This is a restart operation rather than a reset operation because
the register file is not reinitialized.
18.7 General Purpose Digital Input Port Operation
There is one digital, 8-bit, input-only port associated with the ATD
module. It is accessed through the 8-bit Port Data Register (PORTADx).
Since the port pins are used only as inputs, in normal operating modes,
no data direction register is available for this port.
The input channel pins can be used to read analog and digital data. As
analog inputs, they are multiplexed and sampled to supply signals to the
A/D converter. As digital inputs, they supply input data buffers that can
be accessed through the digital port registers. Analog signals present on
the input pins at the digital sampling time that don’t meet the V_IL or V_IH
specification will return unknown digital values.
A read of PORTADx may affect the accuracy of an in progress sample
period but will not affect an in progress A/D conversion.
MC68HC912D60A — Rev. 3.1
Freescale Semiconductor
Analog-to-Digital Converter
Technical Data
357