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Multiple outputs act in unison

Is there a way to have 6 different GPIOs act in unison off one event/action?  I need all 6 to go ON and OFF at EXACTLY the same time based of an event or action.

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  • Hi Brian

    You can't have a single PWM channel trigger 6 outputs, but it is pretty straight forward to set up 6 individual PWM channels to trigger at the same time. 

    You don't mention which nRF52 device you are interested in, but the nRF52832 has 12 PWM channels in total, while the nRF52840 has 16. 

    You could also use 6 of the 8 GPIOTE channels to trigger 6 pins in unison, but I think the PWM is a better choice since each PWM module can handle up to 4 channels easily (with the GPIOTE you would have to fire off 6 events at the same time, versus just 2 for the PWM solution). 

    Best regards
    Torbjørn

  • Torbjørn - The hardware designer connected 6 I/O pins together to try and increase the drive capability.  The 6 I/O need to be driven by the PWM.  Currently I have one PWM driving 4 channels (4 of the outputs), and I have the other two I/O set as disconnected inputs.  I wanted to make sure all of the pins switch at the same time which is why I used only one PWM (all 4 outputs work off same clock).  I would think the outputs need to switch together to avoid shorting the supply.  Thanks for the help!

  • Hi Brian

    How much drive current do you need?

    I am not sure how efficient this method will be in increasing the maximum current, as there is a limit on how much you can draw from all the pins put together, limited by the regulators in the chip. 

    This limit is highly dependent on supply voltage, with a higher supply voltage allowing you to draw a higher current from the pins. 

    Best regards
    Torbjørn

  • Torbjørn - we are trying to drive a single FET that is part of a boost power supply.  E.g. 3V battery thru an inductor to the FET to ground. The  nRF52832 is driving the FET.   We are running a PWM at 400khz.  The Nordic doesn't seem able to pull down/up the FET gate fast enough for the circuit to work.  Specifically it has a hard time pulling DOWN the gate to turn it OFF.  We currently have 4 outputs from the PWM driving the gate.  I have them defined as H0S1, which gives the best results, but still not adequate.  The input capacitance on the current FET is 262nf.  We have a different FET on order with an input capacitance of 32pf.  We are hoping that solves the problem.

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