UIRT2A External Connections
This page describes how to assemble the external connections for the PCB
power, IR emitters, serial port, and external trigger.
This page describes how to connect the UIRT2
Power for the Uirt and PC power up
The Uirt requires
To be able to use the PC power-up feature the Uirt needs a
supply also when the PC is off. ATX based PC's have a 5V standby supply wich
can be used to powerup the PC in several ways. Depending on the motherboard
this can be the powerbutton (of course), Wake On Lan, Wake On Modem, keyboard,
Not all motherboards are the same and there's no
standardization on these features exept for WOL.
WOM seems to be
electronically standardised but the connector is not.
For this reason I
have chosen to use a WOL connector to supply power and to powerup the PC. If
WOL can't be used you can use one of the other methods but this will require
WOL needs a positive pulse to wake-up, WOM needs a
negative one. The power button usually also uses a negative one but this has
needs to be verified.
The Uirt can be used for both methods:
connector only needs a straight 3 wire pin to pin connection.
For WOM or the power button you have to use Output 4 to generate the
Connection to comm port.
If you mount the DB9 connector there's
only a short 9 pin male - female cable required, these can be found cheap in
PC accesories shops. You can also solder the wires directly on the pads. If
ICSP is not required only GND, RXD and TXD need connection.
Connect 2 leds as used on the pcb, The
value for R5 is then 10 ohm. You can also use prewired emitters (like Xantech)
but the value for R5 will have to be defined depending on the type used.
Using the extra outputs.
This is the most difficult to
The power used for these devices must be well choosen, if your
power supply has enough 5V standby you could use this. If relatively high
loads will be connected it will be better to use another supply like the
standard 5 or 12V wich can be derived from a spare hard disk or floppy
connector (red is +5, black is ground and yellow is +12).
outputs can handle currents up to 500mA but I would recommend not to exceed
100mA, this should be sufficient for most applications.
application is a visible led for indication purposes. A resistor in serie is
required (value depends on the desired brightness): 180 to 330 ohm for 5V, 560
ohm to 1K for 12V external power.
A clamping diode is required when a relay is connected.
The picture says it all, simple.