PulseBlasterDDS-I-300
Triggering
The PulseBlasterDDS-I-300 can be triggered in two ways, either by software trigger or hardware trigger. The software
trigger is initiated by sending a command from the host PC. Because these boards are typically used with non real-time
operating systems, the exact time between issuing a software trigger and the board acting on that trigger cannot be
precisely specified. For precision control, the pulse program can also be triggered by setting the HW_Trigger pin to a
logical 0. This will cause the pulse program to be triggered within two clock cycles (starting a program), or a minimum of 8
clock cycles (resuming from WAIT instruction).
Triggering the pulse program has one of the following three effects:
1. Begin execution of a pulse program.
2. Restart execution of a pulse program after the board has been reset.
3. Resume execution of a pulse program which is currently paused by a WAIT instruction.
Relevant SpinAPI functions:
pb_start()
Clock output on BNC0
PulseBlasterDDS-I-300 boards have the capability of outputting a 10 MHz
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signal on the BNC0 connector (PCI boards),
or on one of the on-board IDC headers (USB boards). This signal is a 50% duty cycle square wave derived directly from
the on-board 50 MHz clock oscillator, and is intended for synchronization purposes.
To enable this output, call the following SpinAPI function:
pb_set_radio_control(BNC0_CLK);
To have BNC0 return to normal pulse program behavior, call:
pb_unset_radio_control(BNC0_CLK);
If this clock output is enabled, loading the board with another pulse program will not affect the output clock signal. The
10 MHz signal will continue to be present on the output connector until one of the following events occurs: (1) the computer
is turned off, (2)
pb_unset_radio_control(BNC0_CLK)
is called, or (3)
pb_set_defaults()
is called. Condition 3
may occur if you are using multiple programs to control your PulseBlasterDDS-I-300, and can be avoided by making sure
that only one of the programs calls
pb_set_defaults()
and that this program is not run after the one that calls
pb_set_radio_control(BNC0_CLK).
NOTE: When enabled, this option does not affect the functionality of the Digital Output 0 pin on the IDC connector. This
pin will still serve as a digital output under control of the pulse program.
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Assuming a 50 MHz clock. A 75 MHz clock would give a 15 MHz reference signal.
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18
2017-11-14
