Using TinyG with SSR Relays.. Not Turning On Relays?

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  • October 2, 2013 at 12:23 pm #4681
    mcgyvr
    Member

    No matter what the update from Alden.. the hardware is basically set in stone.
    The 3.3v (2.9-3V) is right at the minimum for any SSR and as such you could have issues. Thats one of the reasons I hate the switch to 3.3V from 5V..

    To move on you should simply construct a transistor driver for the SSR as I had posted about above and be done with it.. A dollar in parts and done..

    The new SSR might work too..Just a difference in manufacturers/specs/tolerances,etc… But its trial/error

    October 3, 2013 at 6:22 pm #4691
    Riley
    Keymaster

    Update… Yes we are looking into this! I think the worst come to worst case for TinyG v8’s is we might need to pull a resistor off the board for that line. Please hold up from doing anything yet (meaning messing with the board 🙂 we are working on getting a solution tested and up on the wiki. Those relays should work just fine with the voltage that the xmega can supply so there is hope.

    Riley

    November 8, 2013 at 1:50 pm #4933
    RustRacer
    Member

    Has there been any resolution to this yet?

    Ben

    August 26, 2014 at 10:54 am #6658
    fponticelli
    Member

    Ping.

    August 26, 2014 at 11:03 am #6659
    alden
    Member

    The v8 outputs are about 3v to 3.2v from the 3.3v processor. On the v9 (not yet released) we have provided a way to generate 5v outputs, but that doesn’t help you much on the v8. There are 3 ways I can think of to drive the SSR from a v8:

    1. Use an external level shifter. The 74LS125 or 126 are good chips for this. Tie the Vcc to 5v and drive the input from the 3v signal. Make sure the enable is set hi or lo depending on which chip you are using.

    2. Find an SSR that actually meets its 3v spec. Seems to be easier said than done.

    3. Cheat the TinyG board by voiding the warranty. It’s possible to drive the on-board components at up to 3.6v (MCU and stepper drivers). If you change out the voltage setting resistors on the switching regulator you can fiddle with the voltage to – say – 3.5v. This might provide enough lift in the outputs to actually drive a marginal relay. I don’t recommend this – it’s very dicey. One slip and you fry the entire board. But it’s possible

    I think option 1 is the best.

    • This reply was modified 10 years, 4 months ago by alden.
    August 26, 2014 at 11:06 am #6661
    fponticelli
    Member

    Do you have any recommendation for a breakout board for solution number 1?

    August 26, 2014 at 11:10 am #6662
    alden
    Member

    I don’t have a breadboard recommendation. There might be some out there. I’d probably just get a DIP version of the chip and breadboard it. You can get 5v off the board – check the schematics. The 125/126 have 4 buffers, so you can do all the pins it you need to.

    August 26, 2014 at 11:13 am #6663
    fponticelli
    Member

    I am sorry about the very basic question. But is this setup a viable option to control a laser using PWM? Or is it just good for an always on/off device (like the spindle)?

    August 26, 2014 at 12:31 pm #6664
    alden
    Member

    Not a bad question. Yes, this setup should work on anything that has up to about a 10 nanosecond rise time requirement. Plenty fast for the PWM channel!

    August 26, 2014 at 12:49 pm #6665
    fponticelli
    Member

    Awesome, thanks!

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