I have a problem with floating pins. I need a LOW on an "Enable" pin right from the start, so I place a PULLDOWN resistor between my "Enable" pin and GND.
Later I need a HIGH on the "Enable" pin. Is that possible?
Backstory:
I want to control a stepper motor using a stepper driver. The stepper driver "step" pin is floating when powering on the Arduino and the motor start to vibrate for about one second. And I dont want it to do that.
The stepper driver has an "enable" pin that need to be HIGH to make the steppers work. So I want to have a LOW on the "enable" pin right from the start and maybe 2 seconds later have a HIGH.
If I have understood you correctly then the usual way to hold a pin low at startup is to put a capacitor between the pin and 0V and a resistor between the pin and Vcc. At power up the capacitor will be discharged and will hold the pin low. After a short delay the resistor will pull it high.
Capacitor value maybe 1μF, resistor maybe 100k, but the values depend on how long you need to hold the pin low.
I could think of one or two, but I'd start with the solution or an RC network as @PerryBebbington suggested since it's simple and usually very reliable.
A with resistor pulled down Output can not be set to HIGH state afterwards via code?
Then I could pulldown the EN pin to GND with a 10k or 4,7kOhm and after the arduino has booted I could set a digitalWrite(enable, HIGH) on that pin? That doesnt work?
