Random Noise On Digital Pins

[tonyman1106]

I am getting random noise on the logic analyzer, by simply pluging in a male to female jumper wire 

[attila]

The Digital IO pins by default, when not driving from Pattern Generator or Static IO, are inputs.

Having the inputs floating, without external drive or pull, can capture radiation pulses. Connecting wire to it will act like an antenna, capturing more noise.

[tonyman1106]

what would cause this problem, This is the first time i  have seen it and i only had for a month.

[hamster]

I get a similar issue on my Rigol scope, where unconnected pins on the logic analyser picks up noise. It is because the inputs have high impedance, minimising the power they take from the circuit under test. Because of this a little bit of noise generates quite a lot of voltage in the probes.

 

The cause is most likely just due to the physics of 'fast' logic signals and poor grounding (due to the use of flying leads. You could add additional ground leads, and maybe twist the signal and GNDs around each other. You could try making a bit of make-shift shielding, and either shied the cables with the actives, or shield the unused leads. (e.g. wrap the bundle in tin-foil).

 

One source of RF noise is anything that deliberately spews out RF signals - e.g. move your cellphone to the other end of the bench (been there, done that!).

[tonyman1106]

I change the USB port it was plugged into seem to have helped