pat_gen :
A digital pattern generator

The pat_gen primitive generates a stream of digital data pattern to an xbit-typed output. In other words, the primitive sequentially outputs each bit defined in the array parameter data when triggered by the input trig. The parameter trig_mode defines whether the primitive is triggered by the positive edge (1), negative edge (-1), or both edges (0) of the input trig (default: 1).

The data pattern can be repeated over time as a whole or in part. The parameters repeat_pos and repeat_num define this repetition behavior. For instance, if the parameter repeat_pos is 3 and repeat_num is 2 for the data pattern data of ‘{1,0,0,1,1,0}, the output bit sequence is:

    1-0-0-1-1-0-1-1-0-1-1-0
                ^     ^
                |     |
                |     +-- second repetition starting from data[3]
                +-- first repetition starting from data[3]

If the repeat_num value is -1, the pattern will be repeated indefinitely.

When the parameter filename is defined, the primitive reads in the named file that defines the parameter values in Python format. For example, the content of a parameter file corresponding to the above case would be:

    data = [ 1, 0, 0, 1, 1, 0 ]
    repeat_pos = 3
    repeat_num = 2

Input/Output Terminals

Name	I/O	Type	Description
out	output	xbit	signal output
trig	input	xbit	trigger input

Parameters

Name	Type	Default	Unit	Description
data	bit array	‘{0}	None	data pattern
repeat_pos	int	0	None	repetition start position
repeat_num	int	0	None	number of repetitions
trig_mode	int	1	None	triggering mode
filename	string	“”	None	parameter definition file