Echelon FT 3150 Smart Transceiver - Manual (Page 46)

Chapter 3 - Input/Output Interfaces
40 FT 3120 / FT 3150 Smart Transceiver Data Book
Direct I/O Objects
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.
Bit Input/Output
Pins IO0 – IO10 may be individually configured as single-bit input or output ports. Inputs may be used to sense TTL-
level compatible logic signals from external logic, contact closures, and the like. Outputs may be used to drive
external CMOS and TTL level compatible logic, switch transistors and very low current relays to actuate higher-
current external devices such as stepper motors and lights. The high (20mA) current sink capability of pins IO0 – IO3
allows these pins to drive many I/O devices directly (refer to Figure 3.5). Figures 3.6 and 3.7 show the bit input and
bit output latency times, respectively. These are the times from which io_in() or io_out() is called, until a value is
returned. The direction of bit ports may be changed between input and output dynamically under application control.
Figure 3.5 Bit I/O
WARNING: After a Reset, the FT Smart Transceiver performs a self-test which includes enabling the 104-107 pull-
up resistors. This could cause a positive level change.
IO10
IO9
IO8
IO0
IO1
IO2
IO3
IO4
IO5
IO6
IO7
High Current Sink Drivers Optional Pull-Up Re-
sistors
IO10
IO9
IO8
IO0
IO1
IO2
IO3
IO4
IO5
IO6
IO7