Microprocessor - Symbol SE955 Integration Manual

• The DBP is sent to the local microprocessor to be decoded.
SE955 Scan Engine
Photo-
diode
Laser
Liquid
Polymer
Scan
Element
* = Logic Low
The laser drive uses multiple forms of feedback (optical and electrical) to control the diode laser to emit constant optical power, and
to ensure compliance with the laser regulatory standards, described in
The scan element is a mirror and magnet assembly cantilevered on a spring. This is a resonant system with a natural frequency of 52
Hz resulting in 104 scans per second. Alternating current forced through a drive coil mounted adjacent to the magnet causes the mirror
to deflect to either side of its steady state position. This deflection causes the laser spot to be scanned across the bar code. A
feedback coil coaxial with the drive measures the amplitude of the scan element and is used to set the scan amplitude. The SE955 is
factory calibrated to generate two user selectable scan angles, 35° and 47° (default).

Microprocessor

The SE955 utilizes a microprocessor to drive the SSI host interface, to control the laser scanning functional blocks, and to perform
general decoder maintenance. A new feature being introduced by the SE955 decoded scan engine is support for Remote Scanner
Management (RSM). For example, through SSI commands, the host can poll the SE955 for a measurement of temperature, as
measured by circuitry on the PCB. For a full listing of the information that is available, see
and Chapter 10, Simple Serial
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.
Analog
Receiver
Laser
Drive
Analog
Parameters
Scan Element
Drive
Figure 1-1. SE955 Scan Engine Block Diagram
Interface.
3
2
8
12
9
10
CPU
11
4
UART 5
7
6
1
Chapter 6, Regulatory Requirements.
Chapter 9, Remote Scanner Management
Getting Started 1-3
GND GND
VBATT
PWRDWN
TRIG*
BPR*
DLED*
AIM/WAKE*
RXD
TXD
RTS*
CTS*
FLASH_DWLD*