Trigger Mode; Trigger Input Termination; Trigger Level; Detailed Description Of The External Analog Trigger Modes - Spectrum M2p.59 Series Hardware Manual

Trigger modes and appendant registers

Trigger Mode

Please find the main external (analog) trigger input modes below. A detailed description of the modes follows in the next chapters..

Table 63: Spectrum API: external trigger mode registers and available settings therefore

Register
SPC_TRIG_EXT0_AVAILMODES
SPC_TRIG_EXT0_MODE
SPC_TM_NONE
SPC_TM_POS
SPC_TM_NEG
SPC_TM_BOTH
SPC_TM_HIGH
SPC_TM_LOW
SPC_TM_POS | SPC_TM_P-
W_GREATER
SPC_TM_POS | SPC_TM_P-
W_SMALLER
SPC_TM_NEG | SPC_TM_P-
W_GREATER
SPC_TM_NEG | SPC_TM_P-
W_SMALLER
For all external edge and level trigger modes, the OR mask must contain the corresponding input, as the following table shows:

Table 64: Spectrum API: trigger or mask and setup for external trigger

Register
SPC_TRIG_ORMASK
SPC_TMASK_EXT1

Trigger Input Termination

The external trigger input is a high impedance input with 5 kOhm termination against GND. It is possible to program a 50 Ohm termination
by software to terminate fast trigger signals correctly. If you enable the termination, please make sure, that your trigger source is capable to
deliver the needed current. Please check carefully whether the source is able to fulfill the trigger input specification given in the technical data
section.
Register
SPC_TRIG_TERM
Please note that the signal levels will drop by 50% if using the 50 Ohm termination and your source also has 50 Ohm output impedance
(both terminatiors will then work as a 1:2 divider). In that case it will be necessary to reprogram the trigger levels to match the new signal
levels. In case of problems receiving a trigger please check the signal level of your source while connected to the terminated input.

Trigger level

All of the external (analog) trigger modes listed above require a trigger level to be set (except SPC_TM_NONE of course). The meaning of
the trigger levels is depending on the selected mode and can be found in the detailed trigger mode description that follows.
Trigger level for the external (analog) trigger is to be programmed in mV:

Table 65: Spectrum API: software registers for external trigger levels

Register
SPC_TRIG_EXT_AVAIL0_MIN
SPC_TRIG_EXT_AVAIL0_MAX
SPC_TRIG_EXT_AVAIL0_STEP
SPC_TRIG_EXT0_LEVEL0

Detailed description of the external analog trigger modes

For all external analog trigger modes shown below, either the OR mask or the AND must contain the external trigger to activate the external
input as trigger source:.

Table 66: Spectrum API: software registers to program external trigger

Register
SPC_TRIG_ORMASK
SPC_TRIG_ANDMASK
Value Direction Description
40500 read Bitmask showing all available trigger modes for external 0 (Ext0) = main analog trigger input
40510 read/write Defines the external trigger mode for the external MMCX connector trigger input. The trigger need to
be added to either OR or AND mask input to be activated.
00000000h Channel is not used for trigger detection. This is as with the trigger masks another possibility for disabling channels.
00000001h Trigger detection for positive edges (crossing level 0 from below to above)
00000002h Trigger detection for negative edges (crossing level 0 from above to below)
00000004h Trigger detection for positive and negative edges (any crossing of level 0)
00000008h Trigger detection for HIGH levels (signal above level 0)
00000010h Trigger detection for LOW levels (signal below level 0)
4000001h Sets the trigger mode for external trigger to detect HIGH pulses that are longer than a programmed pulsewidth.
2000001h Sets the trigger mode for external trigger to detect HIGH pulses that are shorter than a programmed pulsewidth.
4000002h Sets the trigger mode for external trigger to detect LOW pulses that are longer than a programmed pulsewidth.
2000002h Sets the trigger mode for external trigger to detect LOW pulses that are shorter than a programmed pulsewidth.
Value Direction Description
40410 read/write Defines the OR mask for the different trigger sources.
4h Enable secondary external trigger input for the OR mask
Value Direction Description
40110 read/write A „1" sets the 50 Ohm termination for external trigger signals. A „0" sets the high impedance termi-
nation
Value Direction Description
42340 read returns the minimum trigger level to be programmed in mV
42341 read returns the maximum trigger level to be programmed in mV
42342 read returns the step size of trigger level to be programmed in mV
42320 read/write Trigger level 0 for external trigger Ext0
Value Direction Description
40410 read/write Defines the events included within the trigger OR mask of the card.
40430 read/write Defines the events included within the trigger AND mask of the card.
(c) Spectrum Instrumentation GmbH
Main analog external trigger (Ext0)
Range
-5000 mV to +5000 mV
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