Hi,
Motor producing more noise which is affecting other digital circuits.
How do you know about this?
EMI noise may be very complex.
It may be transmitted as electromagnetic wave per air. Then a decoupling capacitor won´t help.
It may be transmitted per wire, then you need filter devices that are useful for HF. A standard 470uF electrolytic capacitor usually is not suitable for HF.
Look for HF surression capacitors or EMI filter capacitors.
The noise may be transmitted by the wire to the motor: --> make this wire as short as possible, use shielded wire, use common mode filter choke, use HF filters close at the controller.
The noise may be produced by the controller (maybe by not having enough dead time at the half brides), it may be caused or not properly suppressed because of poor PCB layout.
Without knowing the source, the bahaviour of noise, the wiring, the PCB layout ... it´s impossible to give good assitance. It´s just guessing.
--> find the source of the problem. Rectifiy the source of the problem rather than curing the symptom.
If you need further assitance, then:
* give scope pictures
* photos of the application and wiring
* PCB layout
* schematic
* software
Klaus