Intermec 073290-001 User Manual

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Chapter 4 — Theory of Operation 
This is specifically not a CK30 requirement, but is expected to be a 
requirement for future products, which will all use the same docking 
connector. 
•  Undecoded scanners use the FPGA count gathering logic (See “1D 
DBP Scanner Interface” on page 78). When an undecoded scanner is 
installed on the docking connector, the TETHERED _PRESENT 
signal is asserted. Software senses this and configures the FPGA to 
switch its count gathering logic from the internal scanner to the tethered 
scanner DBP (video) and SOS signals (TETH_DBP and TETH_SOS) 
through Schmitt-trigger U9. This action also drives low the FPGA 
control line to analog switch U10, isolating the internal scanner from 
the ILLUM_LASEN_RTS and SPEED_RANGE_GDRD signals now 
being used to control the tethered scanner. (Actually, U10 would 
normally already be “open” if internal scanner power is off.) 
•  Decoded scanners are supported as serial (true RS-232) devices using 
RS-232 buffer chip U23 and the “FF” UART signals on the PXA255 
normally used for serial dock communications (See “RS-232 Port” on 
page 89).  Note that this is not the same as the “ST” UART used for 
tethered decoded scanners brought in through the 10-pin Stewart port. 
•  See “Dock Interface” on page 87 for docking connector pin-out and 
tethered scanner power details. 
Dock Scanner Auto-Detect 
A TETH_PRESENT pin is provided on 26-pin docking connector J13 to 
indicate when an undecoded tethered scanner is plugged into the docking 
connector:  
TETH_PRESENT 
Description 
0 Scanner 
installed: 
• 
FPGA count gathering logic takes its DBP and SOS inputs 
from TETH_DBP and TETH_SOS (from docking 
connector). 
• 
SPEED_RANGE_GDRD, ILLUM_LASEN_RTS, and 
SCAN_TRIG signals are isolated from the internal scanner. 
• 
Software turns off power to the internal scanner (exception:  
IT4000). 
Scanner removed: 
• 
FPGA count gathering logic takes its DBP and SOS inputs 
from the internal scanner. 
• 
SPEED_RANGE_GDRD, ILLUM_LASEN_RTS, and 
SCAN_TRIG signals are connected through to the internal 
scanner. 
• 
Software turns on power to the internal scanner (when 
scanning is started) 
 
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CK30 Handheld Computer Service Manual