Simple Serial Interface (Ssi); Power Management - Motorola SE955 Integration Manual

1 - 4 SE955 Integration Guide
The micro-controller contains a watchdog timer. The enabling/disabling and maintenance of this watchdog are
internal to the SE955; the host cannot configure the watchdog. The decoder's reset circuitry holds the
micro-controller in reset after power-up to allow sufficient time for hardware initialization. This reset period is 23
msec. A reset can occur upon power up, or power supply voltage falling below 2.7 V.

Simple Serial Interface (SSI)

The SE955 scan engine is host controlled through the Simple Serial Interface (see
various triggering modes of operation (see
•
Scan mode
•
Aim mode which provides a laser aim dot
•
Blink mode for presentation scanning
•
Continuous mode.
NOTE In Scan mode the pre-selected scan amplitude is used. I.e., 35° and 47° (default). Also see,
on page 8-11
The Aim mode is used to provide a laser aim dot, which can be used to pre-align the scan engine to a bar code
before scanning. To aim then scan, the host would control the engine using the hardware AIM/WKUP* then
TRIG* lines at the SSI interface (see
Interface).
The Blink mode can be used for triggerless operation in presentation scanning applications. To minimize power
consumption, low duty cycle scanning is performed until a change in background is detected. Once detected,
high duty cycle scanning is performed until the bar code, if one is present, is decoded. The scan engine would
then return to low duty cycle scanning until the next change in background is detected (see
on page 8-13).
The Continuous Scanning mode is the mode in which the scan engine is always scanning and decoding (see
Power Mode on page

Power Management

The SE955 has two power states (Awake and Sleep) and two power modes (Continuous Power and Low
Power).
Power States
WAKEUP and SLEEP commands (see
scan engine to set the Power state to Awake or Sleep. The Low Power mode has an automatic timer that puts
the unit into the Sleep state after a specified period of time.
When the SE955 is in the Sleep power state the PWRDWN signal (see
this signal to remove power from the SE955. Do not remove power without using this signal since the
PWRDWN signal is the only indication if the decoder is not transmitting, receiving, decoding, or writing data to
non-volatile memory.
Triggering Modes on page
.
Table 1-3), or by SSI commands (see
8-12).
WAKEUP on page 10-33
Table 1-3), and supports
8-13), including:
Chapter 10, Simple Serial
and SLEEP on page 10-30), are sent to the
Table 1-3) is asserted. The host uses
Scan Angle
Triggering Modes