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D027173_07 CR821X Dual Board Decoded Scan Engine Integration Guide
4.5 – Electrical Control Signals
The CR821x is equipped with inputs and outputs that allow the user to
control the reader and get certain status information via hardware signals.
A brief description of each signal is given in this section. For additional
details on the interaction and timing of these signals, refer to the Timing
Diagrams and Tables in the sections that follow.
Pin 8 - Power Down (output):
The status of PwrDwn is unknown until the
system has booted and is ready for commands. At that point, the PwrDwn
signal will transition LOW to indicate the CR821x is ready to receive
commands. Thereafter, the PwrDwn signal will indicate that the CR821x
is either consuming power in an idle or active mode (when asserted LOW)
or is in a low power state like sleep mode (when assserted HIGH). The
different power modes are described in more detail in Section 4.6.
Pin 9 – Beeper (output):
The nBeeper line is used to indicate a
successful decode, completion of the boot process, errors, and certain
other conditions or events. nBeeper can be configured to transition to a
LOW state for a specified length of time or to output a series of pulses of
a specified duration on a successful decode or on certain error conditions.
Default behavior for this signal is two “beeps” on startup, one “beep” for
a good decode, two “beeps” for a successful configuration barcode read,
and four beeps if a configuration was not applied successfully.
Pin 10 - Good Read (output):
The nGoodRead line is used to indicate
a successful decode. Upon the completion of a successful scan and
decode, the nGoodRead line will be asserted LOW.
Pin 11 – Wakeup (input):
The nWakeUp line is used to change the state
of the reader from Sleep to Idle. Once the CR821x has entered the sleep
state, it may be awakened by asserting nWakeUp with a LOW pulse. Note
that nWakeUp must be HIGH when the CR821x enters the sleep state in
order for nWakeUp to awaken the CR821x on assertion. Also note that
when the sleep state is not being used, this pin should be left open, not
tied low. Please note that the Sleep state is only valid for CR8212.
Pin 12 – Trigger (input):
The nTrigger line is used to activate the reader.
To activate the CR821x, pull the nTrigger line LOW. This is normally used
to cause the reader to scan for a barcode. The Trigger line can also be
used to wake a CR821x from sleep.
Note: When Vin is initially supplied, PwrDwn will stay LOW until the
processor begins booting and will return low when the booting is complete.
If the unit is put to sleep, the PwrDwn signal will then return high. The other
outputs will be LOW for a few milliseconds until the main processor has
completed part of its boot process. These signals should be ignored until
the processor has completed its boot sequence, which will take a maximum
of two (2) seconds, or before the PwrDwn signal has transitioned low after
waking from sleep. See startup timing diagram below for details.
4.6 – Power Modes
Active Mode:
In Active Mode the unit is capturing images and initiating
the decode process and/or storing images. The unit transitions to Active
Mode from Idle Mode when a trigger event is received.
Idle Mode:
In Idle Mode the unit is not actively capturing images.
The processor is fully functioning and communication can take place,
upgrades can be performed, and scripts can be run. Idle Mode is entered
from Boot Mode after power on, from Active Mode after a register defined
timeout in which there are no trigger events, and from Sleep Mode on
receipt of a wake up.
Sleep Mode (CR8212 only):
The imager, illumination, and most of the
processor is powered down. The CPU wake up circuitry, the memory, and
the input/output buffers are powered. The unit enters the sleep state after
a register defined timeout of inactivity. On receipt of a wake up on the
nWakeUp pin, the processor restores the run environment and enters Idle
Mode.
