Thread: Wiring LED to Driverstation
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Unread 22-01-2009, 08:24
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Re: Wiring LED to Driverstation
Quote:
Section 3.1.6.2 Driver Station Digital Outputs of the 2009 FRC Control System manual says: "The DS digital output pins are driven directly by 5V transceiver (SN74LVC4245A device). Be sure to use caution as each pin can source/sink more than 40mA. It is possible to damage the device if too much current is driven on a single pin or the total current supplied by the device on all pins is excessive. Best practice should be to use a limiting resistor to prevent external loads from drawing excessive current, especially for LEDs, be sure to use a series resistor to limit the current." The overview of Driver Station ports earlier in the manual also mentions them: "Digital Output pins 5V output level (8) – Provides 5V TTL for interfacing to digital devices and to drive LEDs (with current limiting resistors)."
I read this which was why I got a resistor with a current drop like I did. My problem was figuring out which of the 3 wires from the digital output should I put to my 2 wire resistor. I didn't want to mess up my DriverStation by wiring it wrong through trial and error.

That Digi-Key part is already wired, big, and ready for panel mounting so I figured why re-invent the wheel if they had a part I could use? :-)

So to repeat I go from red 5V from digital output through my LED and then to the signal pin on the digital output? Is this correct? And then my program can turn it off and on by cycling the digital output in code?