Looking for TTL motor driver help

Discussion in 'The Projects Forum' started by Netwaves, Mar 17, 2015.

  1. Netwaves

    Thread Starter Member

    Feb 9, 2015

    I'm using I2C MCP23017 to control a stepper motor driver. The driver board needs TTL high/low for forward and TTL low/high for reverse. I'm looking for a circuit, maybe a flip flop, so that I only have to use one high/low line from the MCP23017 to cause the driver board lines to flip from high/low to low/high. Anyone know of a circuit or chip that will do what I'm looking for? In case you're interested, I'm using the TA7291S/SG driver chip.

    The logic would look like this:

    H = H/L
    L = L/H


    Here is a copy of my current circuit, A, which works fine. And circuit B that would only use one line from the MCP23017. I'm just not sure what to place between the MCP23017 and the TA7291S to make it happen.

    Maybe a NOT gate tied to one? A 74LS04?

    Last edited: Mar 17, 2015
  2. MaxHeadRoom


    Jul 18, 2013
    The typical stepper driver requires either a low or high for each direction and the step series of pulses to control rate or speed.