Echelon FT 3150 Smart Transceiver - Manual (Page 76)

Chapter 3 - Input/Output Interfaces
70 FT 3120 / FT 3150 Smart Transceiver Data Book
Figure 3.34 Wiegand Input Object
Timer/Counter Input Objects
The FT Smart Transceivers have two 16-bit timer/counters. For the first timer/counter, IO0 is used as the output, and
a multiplexer selects one of IO4 – IO7 as the input. The second timer/counter uses IO1 as the output and IO4 as the
input (see Figure 2.7). Multiple timer/counter input objects may be declared on different pins within a single
application. By calling the io_select() function, the application can use the first timer/counter in up to four
different input functions. If a timer/counter is configured in one of the output functions, or as a quadrature
input, then it can not be reassigned to another timer/counter object in the same application program.
The timing numbers shown in this section are valid for both an explicit I/O call or an implicit I/O call through a when
clause, and are assumed to be for a FT Smart Transceiver running at 10MHz.
Symbol Description Min Typ Max
t
fin
Function call to start of second data edge — 75.6 µs —
t
dw
Input data width (at 10MHz) 200 ns 100 µs 880 ms
t
ibd
Inter-bit delay 150 µs — 900 µs
t
tow
Timeout pulse width — 39 µs —
t
tret
Timeout to function return — 18.0 µs —
t
ret
Last data bit to function return — 74.4 µs —
IO10
IO9
IO8
IO0
IO1
IO2
IO3
IO4
IO5
IO6
IO7
Optional Pull-Up Resistors
t
dw
DATA A
START OF
io_in()
END OF
io_in()
t
fin t
tow
t
tret
t
ret
t
ibd
DATA B
TIMEOUT
TIME