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D027173_07 CR821X Dual Board Decoded Scan Engine Integration Guide
4.2 – Electrical System Block Diagram
4.1 – System Requirements
4 - Electrical Specifications
The CR821x Decoded scan engine is a complete barcode scanning
system that can be easily integrated into any device.
The block diagram below shows the main components of the system.
Power Supply:
The CR821x is powered from the host via the
V
in
and
Gnd pins.
V
in
must be within the range specified in section 4.14 when
measured at the decoding board.
V
in
must be maintained with varying
loads, such as when the illumination is turned ON and OFF.
Host Ribbon Cable (FFC):
The impedance of the cable for the USB data
lines should be 90 ohm differential. For 3.3V operation, a ribbon cable of
no more than 6.0” in length can be used with a 0.28 mm [.011”] trace
width and 0.3 mm trace thickness. Longer cables can be used at higher
voltages.
Scan Engine to Decode Board Flex Cable (FPC):
When leveraging a
non-bracketed design, care should be taken to alleviate bend stress on
the flex cable, which could lead to damage of that cable. The minimum
bend radius for this cable is 2.0 mm. Drawings can be provided upon
request to aid in design. Flex cable length should not exceed 6.0”.
Power Sequencing:
There is no special power sequence needed for the
CR821x as long as the max and min voltage and current specifications
are met. However, if the voltage on a pin is greater than
V
in
, such as
when powering on, then current will flow from the pin to
V
in
through
the pull up resistors.
Thermal Requirements:
The operating temperature range for the CR821x
is -20 ºC to 55 ºC (-4ºF to 131 ºF) unenclosed. Special care should be
taken to ensure the temperature at the image sensor does not exceed 70
ºC and the temperature at the processor does not exceed 100 ºC.
DECODE
PCBA
FLEX CABLE
RIBBON CABLE (RS232/USB)
NU = Not Used on USB Model
Power
Illum. Control
TXD/nGoodRead
CTS/USB D+
RTS/NU
PwrDwn
nBeeper
nGoodRead/NU
nWakeUp
nTrigger
RXD/USB D-
GND
V
IN
RS232 Polarit/NU
12C Bus
Image Control
Image Data
OPTICAL
ENGINE
