Re: How is corrct from the attached diargam
You did not mention so far for what kind of application all the 6 motors will be used, but if there is the need of real time geometric calculations to be done by the uC ( eg not synchronized steps, but interspersed at non-integer rates ), the use of delays will ruin the operation - or at the best case, will dramatically reduce the maximum speed of motors . As mentioned above, you should use interrupts to generate the cadence of the steps.