Theory of Operation
TDS 340A, TDS 360 & TDS 380 Technical Reference
3–11
control clock (CC) and the control data (SDATA_OUT) control this shift register.
Bit 7 is clocked in first, and bit 0 is clocked in last.
The output of the analog trigger is a differential pair of +5 V referenced ECL
signals. Output pins 20 and 21 swing full ECL levels, terminated at 75 W into
the trigger logic.
Trigger Logic. Trigger logic is the digital part of the trigger system. It is com-
posed of discrete positive referenced ECL logic. Trigger logic performs the
following functions:
It selects the trigger event. The CPU serially selects analog trigger
(TRIG_GATE), field 1, field 2 (TV_FIELDS), any field (ANY_FIELD), or
lines (CSYNC). The different modes are dependent on trigger related
front-panel settings.
It accepts all trigger events and decides which event will finish the acquisi-
tion. The analog holdoff qualifies the main trigger event to become the main
used trigger.
The CPU system contains a 68331 microprocessor that controls the entire
instrument. The processor passes waveforms and text on to the display system.
The Main Board contains both the CPU and display systems, and the firmware
ROMs.
The CPU coordinates all oscilloscope activities. It also directs the activities of
the front-panel processor using a serial interface.
CPU Clocks. Processor clocks are derived from 60.6 MHz oscillator Y401. The
TBC divides the 60.6 MHz clock by 4 for a PROC_CLK of 15.15 MHz.
Interrupts. The 68331 supports seven levels of auto-vectored interrupts dedicated
to different interrupt levels. The TBC, display system, and option board generate
interrupts.
Reset. The CPU resets both at power-on and power-off using the reset signal.
Reset controller U606 controls system reset. Power-on reset asserts for a
minimum of 400 ms after the +5 V supply stabilizes. Power-off reset asserts
when the supply falls below a usable threshold.
Memory. The memory subsystem includes 32 K 8 NVRAM for power-off
storage and dynamic RAM for the main system RAM.
CPU System
To Next Page
Loading...
Need help?
General
