Agilent Technologies 1100 Series Reference Manual page 264

8
Theory of Operation
ASIC — Application Specific Integrated Circuit
The 304-pin application specific integrated circuit (ASIC) provides interfacing
to external devices through drivers, including GPIB, CAN, APG remote, and
RS-232C. It is connected directly to the four control LEDs located near the
connectors on the board and the 8-bit configuration switch which is used to
configure the address for the GPIB communication, the Baud rate for RS-232C
transfer, and so on. For switch settings, refer to the Installing Your
Agilent 1100 Win System handbook.
In addition, it controls the cooling fan via the PWM (pulse width modulation)
driver. Movement of the cooling fan is sensed by the microprocessor.
Main processor
The Motorola MC 68332 microprocessor acts as the main processor with a
clock frequency of 16 MHz. It exchanges data with the ASIC through the core
bus as well as with the SRAM (static random access memory) of 4 × 512
kilobyte, the flash EEPROM (electrically erasable programmable read-only
memory) of 1 MB and the 1 × 128 KB battery-backed
NV-RAM (non-volatile). Battery life is designed to last for more than 25 years
under normal operating conditions.
Control lines provide communication to the frontend board, which provides
high voltage power supplies for the flash lamp and the photomultiplier tube
(PMT) and contains the data acquisition section.
FPGA—Field Programmable Gate Array
The FPGA is loaded with code to control the timing of the flash ignition and
the data acquisition. Thus a realtime control of these critical functions is
achieved without processor control.
Excitation/Emission Monochromator Motor Control
A chopped motor driver IC provides the signal to run the excitation/emission
monochromator motor in positioning or rotation mode.
Encoder Signal Acquisition
Each monochromator includes an optical encoder to get the actual position of
the device. The two encoder signals are amplified and prepared for
A/D-conversion.
266 1100 Series FD Reference Manual