ILX Lightwave LDC-3700 Series User Manual

Since the lower eight address lines in the 80 188 architecture are also used as data lines, an address latch, U402,
holds necessary address information when data is loaded onto the bus. Tius latch is enabled by the ALE signal
from the 80 188.
5.4.2 Memory
The LDC-3700 Series Laser Diode Controller uses three types of memory. RAM memory, U404 (see Figure 7.6), is
retained only while power is applied to the unit. ROM memory, U403, contains the internal instructions that make
the LDC-3700 Series Laser Diode Controller function. The Uurd type of memory is electrically erasable pro-
gramable memory, EEPROM, U405. U406 is reserved for ROM expansion or other optional future uses.
EEPROM stores calibration constants and other data which must be retained even when power is removed from the
unit. Examples of data stored in this memory include the TEC and LASER parameters and calibration constants.
EEPROM may be reprogrammed at least 10,000 times, providing ample capacity for most applications.
5.4.3 Optically Isolated Serial Interface
The 80188, in the LDC-3700 Series Laser Diode Controller, communicates
with external TEC and LASER
conrrollers through a serial interface. Parallel data from the microprocessor is converted to a bidirectional serial
signal at the asynchronous serial interface which is comprised of
U4l9 - U422 (see Figure 7.7).
5.4.4 Front Panel Interface
The front panel interface (see Figure 7.6) is a latched parallel VO
port which consists of U407 (data lines) and
U124 (address lines). This VO port is used for communicating with the front panel displays, LEDs, and switches.
5.4.5 Optional GPIB Interface
The
123 1 IEEE-488.2lGPIB interface, shown in Figure 7.8, uses the 9914 interface chip, U412, to control its
operatlous. The interface latches GPIB data through U413 and control information through U414. The clock for
the
99 11 is provided by the 80188 (U401) CLKOUT line.
5.4.6 Data Protection at Power-Down
If the AC line voltage begins to fail, this condition is detected and U417 (see Figure 7.6) generates an interrupt of
the n~icroprocessor.
If the voltage at pin 4 of U417 falls below 1.3 volts, U417 will trigger a non-maskable
tnrcrnlpt. This interrupt is used to save all of the critical data wluch has not yet been saved in non-volatile memory.
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ILX Lightwave LDC-3700 Series Specifications

General

Brand	ILX Lightwave
Model	LDC-3700 Series
Category	Controller
Language	English