MMCCMB2107 Freescale, MMCCMB2107 Datasheet - Page 414

• Manufacturer Part Number: MMCCMB2107
• Manufacturer: Freescale

Specifications of MMCCMB2107

• Lead Free Status / RoHS Status: Not Compliant

Queued Analog-to-Digital Converter (QADC)
18.8.4 Port QA Data Direction Register
Technical Data
414
NOTE:
The port data direction register (DDRQA) is associated with the port QA
digital I/O pins. The bidirectional pins may have somewhat higher
leakage and capacitance specifications. Any bit in this register set to 1
configures the corresponding pin as an output. Any bit in this register
cleared to 0 configures the corresponding pin as an input. The software
is responsible for ensuring that DDR bits are not set to 1 on pins used for
analog inputs. When the DDR bit is set to 1 and the pin 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 the data
direction setting, and the multiplexed address outputs are driven. The
data returned during a port data register read is the value of MA[1:0],
regardless of the 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 or PQA4, is ignored. The port
pins are forced to be digital inputs for ETRIG1 and/or ETRIG2. The data
driven during a port data register read is the actual value of the pin,
regardless of the 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.
Since port QB is input-only, a data direction register is not needed.
Therefore, the lower byte of the port data direction register is not
implemented.
Freescale Semiconductor, Inc.
For More Information On This Product,
Queued Analog-to-Digital Converter (QADC)
Go to: www.freescale.com
MMC2107 – Rev. 2.0
MOTOROLA