MMC2114 MOTOROLA [Motorola, Inc], MMC2114 Datasheet - Page 440

• Manufacturer Part Number: MMC2114
• Description: M CORE Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Queued Analog-to-Digital Converter (QADC)
19.8.4 Port QA and QB Data Direction Register (DDRQA and DDRQB)
Advance Information
440
NOTE:
The Port QA and QB Data Direction Register (DDRQA and DDRQB) are
associated with port QA and QB digital I/O pins. Setting a bit in these
registers configures the corresponding pin as an output. Clearing a bit in
these registers configures the corresponding pin as an input. During
QADC initialization, port QA and QB pins that will be used as direct or
multiplexed analog inputs must have their corresponding data direction
register bits cleared. When a port QA or QB pin that is programmed as
an output is selected for analog conversion, the voltage sampled is that
of the output digital driver as influenced by the load.
When the MUX (externally multiplexed) bit is set in QACR0, the data
direction register settings are ignored for the bits corresponding to
PQA[1:0], the two multiplexed address (MA[1:0]) output pins. The
MA[1:0] pins are forced to be digital outputs, regardless of their data
direction setting, and the multiplexed address outputs are driven. The
data returned during a port data register read is the value of the MA[1:0]
pins, regardless of their data direction setting.
Similarly, when the external trigger pins are assigned to port pins and
external trigger queue operating mode is selected, the data direction
setting for the corresponding pins, PQA3 and/or PQA4, is ignored. The
port pins are forced to be digital inputs for ETRIG1 and/or ETRIG2. The
data returned during a port data register read is the value of ETRIG[2:1]
pins, regardless of their data direction setting.
Use caution when mixing digital and analog inputs. They should be
isolated as much as possible. Rise and fall times should be as large as
possible to minimize ac coupling effects.
Freescale Semiconductor, Inc.
For More Information On This Product,
Queued Analog-to-Digital Converter (QADC)
Go to: www.freescale.com
MMC2114 • MMC2113 • MMC2112 — Rev. 1.0
MOTOROLA