UIRT2A External Connections

This page describes how to assemble the external connections for the PCB power, IR emitters, serial port, and external trigger.

UIRT2 A connections
This page describes how to connect the UIRT2 A

Power for the Uirt and PC power up
The Uirt requires external 5VDC.
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, mouse etc...
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 different wiring.
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:
The WOL 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 negative pulse.

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.

Optional emitters.
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 describe.
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).
The darlington outputs can handle currents up to 500mA but I would recommend not to exceed 100mA, this should be sufficient for most applications.
A simple 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.



External push-button.
The picture says it all, simple.