Info leds…. it's possible?



  • Hi,

    Ask if this is possible …

    I have a Tevo Little Monster printer, in the original assembly, there are two LEDs that light, one when the bed has reached the temperature and another when the Nozzle reaches the temperature.

    Is there any way to get this or similar with the Duet board?


  • administrators

    Not without adding additional LEDs.to your system. May I ask why you need this?



  • I think its a great idea, simple visual cues to remind people to take certain actions or to quickly be able to assess the status of a machine at a glance are great, would be amazing in a printer farm.

    You could have

    Red Bed heated
    Yellow hotend heated
    Green print complete

    In any case you can attach LEDs in various ways (fan headers on Duet or Duex2/5 boards) and use gcode to turn them on/off when you want them to.


  • administrators

    Yeah i can see why it could be useful in a printfarm type environment especially if you did not want to add a screen to each printer.

    Well spare IO pins can be controlled with the M42 Gcode

    https://duet3d.com/wiki/Using_servos_and_controlling_unused_I/O_pins

    So connecting a small LED +resistor to limit current to one of those pins and then use M42 within a macro or your start gcode/finish gcode to switch the LED on /off.



  • How can know the resistor I must use?



  • It depends on supply voltage applied to LED and LED's type. If you are going to attach LEDs to FAN headers then Vs = Vin (Duet supply voltage 12V or 24V). For LED you need forward voltage drop Vf and working current Id. Then R = (Vs-Vf)/Id. If voltages is in Volts and currents in mA then R would be in kOhms. Forward voltage drops for LEDs typically are: red - 1.8V, green - 2.2V, blue/white - 3.5V. Working currents are about 10-20mA (the greater current the brighter LED lights). For example, Vs =24V, red LED, Id = 10mA then R = (24-1.8)/10 = ca. 2.2kOhm. You can check how bright LED lights simply connecting it in series with choosen resistor directly to board power supply. HTH


  • administrators

    If you are using a spare I/O pin on the expansion connector, then connect the LED with series resistor between the pin and ground. The voltage will be 3.3V, so base your resistor value on that. You won't be able to get more than about 4mA from the output.

    If you have any spare fan and/or heater outputs on the Duet, you can use those, and the voltage will be VIN (12V or 24V).



  • when using LED stripes they are controlled with ground (+12V, R, G, B)

    are there any pins i can use to switch ground on/off with a G command?
    I have the duetwifi+duet5x

    as i under stand i have to use

    M106 P3 I-1 ; disable Fan on duet5x
    M106 P4 I-1 ; disable Fan on duet5x
    M106 P5 I-1 ; disable Fan on duet5x

    does it switches ground to or just the + pin?

    regards

    Phil


  • administrators

    @phil_ae said in Info leds…. it's possible?:

    when using LED stripes they are controlled with ground (+12V, R, G, B)

    are there any pins i can use to switch ground on/off with a G command?
    I have the duetwifi+duet5x

    as i under stand i have to use

    M106 P3 I-1 ; disable Fan on duet5x
    M106 P4 I-1 ; disable Fan on duet5x
    M106 P5 I-1 ; disable Fan on duet5x

    does it switches ground to or just the + pin?

    regards

    Phil

    That's correct. The FAN- pin is switched to ground.



  • thank you have it working, switching on/off the colors using M106 Px I1 or i0,
    added some lines to the code in cura to turn on all colors when start printing und turn off blue and red when finished (green light indicated print finished)

    but i am looking for initial heating but cant find it in the config.g over the system editor.

    can you tell me where to find the code for the initial heating?

    thank you

    Philipp



  • How about rgbw neopixel? Is that pissable?


  • administrators

    The Neopixel is almost impossible to drive efficiently because the processor can't do anything else while the data is being sent. The DotStar is a better option because it uses standard SPI protocol.



  • @dc42 Speaking of DotStars, is there support for them yet? (M150)


  • administrators

    @jml said in Info leds…. it's possible?:

    @dc42 Speaking of DotStars, is there support for them yet? (M150)

    So far this is only supported on a board that we made for an OEM customer that has a dedicated output connector for these LEDs. It would be possible to support them on the Duet WiFi using the shared SPI channel, but you would need some external hardware (half a 74HCT32 chip, or one 74HCT02 I think) to gate the clock and level shift the signals to 5V.

    Also bear in mind that a strip of DotStars draws up to 60mA per LED, so if you have more than about 20 then you should use a separate 5V power supply.


Log in to reply