WaveBook/512 and WaveBook/512H
03-06-02
WaveBook Operation Reference 3-3
Digitizing Signals via the A/D Converter
The signal is then switched over to the A/D converter and digitized to 12 bits in 1 µs. Note that the A/D
converter's input can be switched to the expansion signal input, allowing the device to read one of 64
possible expansion channels (supplied by up to eight WBK10 expansion chassis). A digital signal
processor (DSP) processes the digitized value and corrects the value for gain and offset errors. The DSP
places the corrected result into the FIFO data buffer that holds the samples until the PC reads the data. If the
sample is used for triggering, the DSP determines if a valid trigger event has occurred.
Using a Sample for Triggering
WaveBook includes low-latency analog or TTL-level triggering. The analog trigger detector examines
channel 1 to determine if a trigger has occurred. The selected low-latency trigger is presented to the control-
and-timing circuit that starts the acquisition after the trigger. The TTL trigger is taken directly from the
digital I/O port. A detailed discussion of
triggering
begins on page 3-9.
Control, Timing, and Signal Processing
The control-and-timing circuit and the Digital Signal Processor (DSP)
The control-and-timing circuit, and the Digital Signal Processor (DSP) work together to coordinate
activities. Every sample time, the DSP (a) reads from the scan sequence table, and (b) accordingly programs
the control and timing circuit for the next sample. The control-and-timing circuit waits precisely until the
start of the next sample, then selects:
•
the input channel
•
PGA gain
•
level-shifter offset
•
A/D input source
The control-and-timing circuit conveys this information to any attached expansion units and precisely
controls the A/D conversion timing.
The EEPROM
The EEPROM holds the calibration information needed for real-time sample correction.
Reading from and Writing to the Digital I/O Port
The digital I/O port is read and written by the Digital Signal Processor to transfer bytes of digital data.
It may be used as a simple 8-bit input port or as a 32-address byte-wide I/O port.
The high-speed EPP/ECP interface circuit connects the WaveBook and any attached printer to the PC via
standard DB-25 connectors. When the WaveBook is active, the interface holds the printer in a stable state;
and when the WaveBook is inactive, the interface connects the PC to the printer.
The WBK Options
WaveBook operation can be enhanced by the use of various WBK option cards and modules. A brief
synopsis of each option is presented on page 3-4, while more detailed information is provided in
independent document modules. The location of WBK card options, internal to the WaveBook/512 series
products, are illustrated in the following figure. The board layout includes jumper locations that the cards
plug in to.
Reference Note:
The WBK option cards and modules that are listed with a synopsis, beginning on page 3-4, are detailed
later in this user’s manual. The detailed information is provided in the
WBK Option Cards and Modules
User’s Manual
(p/n 489-0902). The WBK document modules are presented in alpha-numerical order and
include product specifications.
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