Specifications

PL 3120/PL 3150/ PL 3170 Power Line Smart Transceiver Data Book 89
Because the period function measures the delay between two consecutive active edges, the invert option has no effect
on the returned value of the function for a repeating input waveform.
Pulsecount Input
A timer/counter can be configured to count the number of input edges (up to 65,535) in a fixed time (0.8388608 second)
at all allowed input clock rates. Edges can be defined as rising or falling. This object is useful for average frequency
measurements, or tachometer applications (see Figure 3.46).
0.84 s
STOPSTART
t
ret
t
fin
READ
TIMER/
COUNTER
FLAG AND
EVENT
REGISTER
CLEAR FLAG
END OF
io_in()
START OF
io_in()
mux
Event Register
Event Register
IO10
IO9
IO8
IO0
IO1
IO2
IO3
IO4
IO5
IO6
IO7
System Clock
Divide Chain
Timer/Counter 2
Timer/Counter 1
Reference Figure 3.40
Optional Pull-Up Resistors
IO11
Symbol Description Typ @ 10MHz
t
fin
Function call to input sample 86 µs
t
ret
Return from function 52/22 µs*
*If the measurement is new, t
ret
= 52µs. If a new time is not being returned, t
ret
= 22µs.
Figure 3.46 Pulse Count Input Latency Values
This is an edge-sensitive function. The clock driving the internal counter in the PL Smart Transceiver is the actual input
signal. The counter is reset automatically every 0.839 second.