PULSE - One-shot pulse delay and stretch

A PULSE block produces configurable width output pulses with an optional delay based on its parameters. It operates in one of two modes:

If WIDTH=0, then it acts as a delay line. The input pulse train will just be replayed after the given DELAY
If WIDTH is non-zero, then each pulse edge that matches TRIG_EDGE will be delayed by the specified DELAY, then generate NPULSES pulses of width WIDTH, with rising edges separated by STEP

Fields

Name	Type	Description
ENABLE	bit_mux	Reset on falling edge, enable on rising
TRIG	bit_mux	Input pulse train
DELAY	time	Output pulse delay (0 for no delay)
WIDTH	time	Output pulse width (0 for input pulse width)
PULSES	param	The number of pulses to produce on each trigger, 0 means 1
STEP	time	If pulses > 1, the time between successive pulse rising edges
TRIG_EDGE	param enum	INP trigger edge 0 Rising 1 Falling 2 Either
OUT	bit_out	Output pulse train
QUEUED	read uint 1023	Length of the delay queue
DROPPED	read	Number of pulses not produced because of an ERR condition

Delay line

If WIDTH=0, then the Block acts as a delay line. DELAY must either be 0 or 5+ clock ticks. TRIG_EDGE, STEP, and NPULSES are ignored.

If DELAY=0 the Block is a simple pass through:

(Source code, png, hires.png, pdf)

If DELAY is non-zero, rising and falling edges will be inserted in the queue and output after the given DELAY:

(Source code, png, hires.png, pdf)

0 < DELAY < 5 will be treated as DELAY=5:

(Source code, png, hires.png, pdf)

Pulse train generation

If WIDTH != 0 then the Block will operate in pulse train mode. If NPULSES is 0 or 1 then it will produce a single pulse for each matching input pulse:

(Source code, png, hires.png, pdf)

The output pulses are queued, so multiple pulses can be queued before output:

(Source code, png, hires.png, pdf)

The TRIG_EDGE field can be used to select whether an input pulse queues an output on rising, falling, or both edges:

(Source code, png, hires.png, pdf)

(Source code, png, hires.png, pdf)

(Source code, png, hires.png, pdf)

0 < WIDTH < 5 will be treated as WIDTH=5:

(Source code, png, hires.png, pdf)

If PULSES > 1 then multiple output pulses will be generated, separated by STEP:

(Source code, png, hires.png, pdf)

(Source code, png, hires.png, pdf)

Pulse period error

The following example shows what happens when the period between pulses is too short. To avoid running output pulses together, the DROPPED field is incremented and the input is dropped:

(Source code, png, hires.png, pdf)