Have an issue where I am controlling some fets to control a motor. THe port pins turn the fet on/off through an npn transistor.

Issue is that at powerup the default state of the port pins before init is turning fet on.

IT takes a few milli seconds right now from when power is applied until init.c can reset port pins. If I could make it happen faster (sub milli second) that may be enough.

Aside from redesigning circuitry is there any other work around?

> I am controlling some fets to control a motor.

> Aside from redesigning circuitry is there any other work around?

IMO, I'd be leery of relying on timing to "correct" a control line.

Startup and shutdown conditions, besides the operational states, should be accounted for in your design. You have identified one startup issue. What about shutdown? If the motor is running (or not), what happens if the controller is turned off or disconnected or disabled? Is there a fail-safe requirement? Even if there is not a requirement, perhaps that would be a beneficial feature?

Regards

So can you pull the pin to the desire level with a weak pull up/down?

You could add assembler code in the reset handler in startup.s to configure the critical pins as outputs and state. This would be the minimal time, and doesn't need to get PLL's running, which normally sucks up some time.

As blue_z indicates this is a pretty sloppy way of doing things, you need a proper power-on-reset circuit, something that can hold things in a safe state until you have control of the system.

Thanks, this is what I was looking for.