MMC2107 - Freescale Semiconductor

Freescale Semiconductor, Inc.
Queued Analog-to-Digital Converter (QADC)
Signals
18.5.2 Stop Mode
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Freescale Semiconductor, I
18.6 Signals
The QADC enters a low-power idle state whenever the QSTOP bit is set
or the part is in stop mode.
QADC stop:
• Disables the analog-to-digital converter, effectively turning off the
analog circuit.
• Aborts the conversion sequence in progress
• Changes the data direction register (DDRQA), port data registers
(PORTQA and PORTQB), control registers (QACR2, QACR1, and
QACR0) and the status registers (QASR1 and QASR0) to
read-only. Only the module configuration register (QADCMCR) is
writable.
• Causes the RAM to not be accessible, can not read valid results
from RAM (result word table and CCW) nor write to the RAM
(result word table and CCW).
• Resets QACR1, QACR2, QASR0, and QASR1
• Holds the QADC periodic/interval timer in reset
Because the bias currents to the analog circuit are turned off in stop, the
QADC requires some recovery time (t SR ) to stabilize the analog circuits.
The QADC uses the external pins shown in Figure 18-2. There are eight
channel/port pins that can support up to 18 channels when external
multiplexing is used (including internal channels). All of the channel pins
can also be used as general-purpose digital port pins. In addition, there
are also two analog reference pins and two analog submodule power
pins.
The QADC has external trigger inputs and the multiplexer outputs
combined onto some of the channel pins.
MMC2107 – Rev. 2.0
Technical Data
MOTOROLA Queued Analog-to-Digital Converter (QADC) 405
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