Digital circuitry
Refer to
Figure 4-5 for the following discussion on digital circuitry.
The core digital circuitry uses a Motorola 68332 microcontroller running at 16.78MHz. The
m
emory configuration includes two 256K X 8-bit EEPROMs and two 128K X 8-bit RAMs used
in parallel to utilize the 16-bit data bus of the MPU. The RAM is battery backed-up, providing
continued storage of data buffer information during power-down cycles, and flash ROM support
allows internal firmware upgrades using either the serial or GPIB port for downloading new
firmware. All calibration constants and save setup o are stored in a separate serial EEPROM.
Setups 1 through 4 are stored in battery backed up RAM.
External communication is provided via GPIB and serial interfaces. A 9914 GPIA IEEE-488
standard interface IC is used for the GPIB, and a 68332 Queued Serial Module (QSM) provides
the serial UART. For internal communications, the Time Processing Unit (TPU) is used for
serial communications with the front panel display module, and both the TPU and QSM handle
d
igital-to-analog interfacing.
Troubleshooting 4-11
A/D
Control/Data
Voltage Source
Control
ROM
U15, U16
RAM
U12, U14
Reset
E PROM
U17
2
A/D Interface
U9, U25
Microprocessor
U3
Serial
Interface
U4
GPIB
U6, U13
U20
RS-232 Interface
IEEE-488 Interface
To Display
Board Controller
Trigger
U23
Digital I/O
U7
Trigger
Digital
I/O
16.78MHz
Figure 4-5
Digital circuitry
block diagram
2410-902-01.book Page 11 Monday, November 7, 2005 2:49 PM
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