RadioProcessor
Control Lines
To control the operation of the RadioProcessor, each instruction in the pulse program specifies a flag word
which sets both the internal control lines and user programmable digital outputs. The control lines stay in the
given state for the duration of the instruction. The internal control lines are described below:
Control Line
Function
frequency select
Selects between the available frequency registers.
cos channel phase select
Selects between the available cos phase registers.
sin channel phase select
Selects between the available sin phase registers.
TX channel phase select
Selects between the available TX phase registers.
tx_enable
Enables TX output on the Analog Out connector. If this control line is
disabled, the Analog Out channel is turned off (zero output voltage).
phase_reset
When this control line is enabled, all DDS channels will be reset to their
time=0 phase. For example, if a channel is set to use a phase register with
90deg, it will be reset to the midpoint output level and stay that way until
the phase reset control line is disabled. This allows the the phase of pulses
to be synchronized between scans.
trigger_scan
When this control line is enabled, a scan will be triggered and data
acquisition will begin. Acquisition continues until the desired number of
complex points have been captured as specified by the acquisition
parameters. Once scanning has been triggered, it will continue until all
points have been captured, regardless of the state of this control line. A
scan is triggered when this control line transitions from a 0 to 1, so to start
a new scan, the value of this line must be returned to 0 before being set to
1 again.
Table 4:
Internal control lines.
Relevant spinapi functions:
pb_start_programming()
pb_inst_radio()
pb_inst_radio_shape()
pb_inst_radio_shape_cyclops()
pb_stop_programming()
Triggering
The RadioProcessor 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 RadioProcessor 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.
2020-10-07
20
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