PicoScope 7 Software
Available on Windows, Mac and Linux
Spikes on logic analyser trace
Spikes on logic analyser trace
Hi,
Hopefully this is in the right place. I am looking at some digital signals for a LED matrix display.
I am not sure if these little spikes are actually pulses or noise being captured. They are in the region of 10-15ns where the clock high pulse width is 400ns, they also do not make sense where they happen. A0 is the row select so should not change until 160 clock pulses (number of columns). The ones on D3 / D4 LED colour are after the falling edge so again do not make any sense.
Bob
Hopefully this is in the right place. I am looking at some digital signals for a LED matrix display.
I am not sure if these little spikes are actually pulses or noise being captured. They are in the region of 10-15ns where the clock high pulse width is 400ns, they also do not make sense where they happen. A0 is the row select so should not change until 160 clock pulses (number of columns). The ones on D3 / D4 LED colour are after the falling edge so again do not make any sense.
Bob
- Attachments
-
Re: Spikes on logic analyser trace
What threshold levels have you used for the digital inputs ?
Is your GND grounding solid ?
You can also use 1 analog input on 1 of the digital inputs with strange spikes so you can see what the analog signal does when the spikes appear.
Benno
Is your GND grounding solid ?
You can also use 1 analog input on 1 of the digital inputs with strange spikes so you can see what the analog signal does when the spikes appear.
Benno
Re: Spikes on logic analyser trace
Hi Benno,
I put all 4 of the GND signals to ground, that made it better, I then changed the threshold from 5v to 4v and it is now giving me what I was expecting.
I am not sure if the extra ground connections made the difference but not going to remove them. What I do not understand is why lowering the threshold made it better, I would have thought it would have been worse.
Regards,
Bob
I put all 4 of the GND signals to ground, that made it better, I then changed the threshold from 5v to 4v and it is now giving me what I was expecting.
I am not sure if the extra ground connections made the difference but not going to remove them. What I do not understand is why lowering the threshold made it better, I would have thought it would have been worse.
Regards,
Bob