HP 54520 Series - Page 97

Figure 5-9
Trigger
State Trigger Mode
Present Softkey
The present softkey sets the oscilloscope to trigger when the pattern is
either present or not present. The pattern is checked for only on the
designated clock edge.
Holdoff Softkey
The holdoff softkey allows you to select the amount of holdoff. Holdoff
disables the trigger circuit for a selectable time period after the state event
has occurred. Holdoff is selected in 20 ns time increments, from 40 ns to 320
ms, or for events (count of states) 2 to 16,000,000. The maximum state
counting rate is 70 MHz.
Figure 5-9 shows a three-channel timing diagram. For this example, the
clock is a rising edge on channel 3. The oscilloscope was also set to look for
when a pattern is present, and the oscilloscope is looking for a high on
channels 1 and 2. You may notice that channels 1 and 2 are both high during
clock pulses A, B, and C. In the state mode, the pattern is checked for
validity only on the selected clock edge. On the rising edge of clock pulses A
and B, channel 2 is a low level. Therefore, the pattern is valid only on the
rising edge of clock pulse C.
~
3720839
5-14