Omega 1002 manual Trigger Method Selection

3.2.2.8.2 Trigger Method Selection

There are several trigger methods that can be selected by the user (see section 1.4.5):

[Bit1,Bit0 ]	Descriptions
[ 0, 0 ]	General trigger mode.
	8254 timer 0 trigger (internal pacer trigger ) or software
	trigger.
[ 0, 1 ]	External clock trigger mode.
[ 1, 0 ]	Pre-trigger mode.
[ 1, 1 ]	Post-trigger mode.

Note:

1.In the general trigger mode, both the 8254 timer 0 and the software trigger are used as the A/D trigger signals. The timer 0 and the software trigger should not be used at the same time! This means the user should not generate a software trigger while the 8254 timer 0 is activated!

2.In the external clock trigger mode, an external input is taken as the A/D trigger signal. A single falling edge of the external trigger will generate a single A/D trigger.

3.The pre-trigger mode employs the 8254 timer 1. The user should first configure timer 1, then set the trigger mode to pre-trigger. Once the pre-trigger mode has been activated, it will automatically turn on timer 1 and start the A/D trigger. This will continue until a falling edge from an external trigger signal is received. Any change to the trigger mode selection will turn off the pre-trigger mode.

4.The post-trigger mode employs the 8254 timer 1. The user should first configure timer 1, then set the trigger mode to post-trigger. Once the post-trigger mode has been activated, it will automatically turn off the timer 1 until it receives a falling edge from an external signal. Any change to the trigger mode selection will turn off the post-trigger mode.

5.The A/D trigger selection is set to 0 after power-on or hardware reset.

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