Hi, As promised I tried 'scoping my Cubieboard 2 running MPD today. This is the frst time I have tried to 'scope a SOC board.
No matter how and where I grounded my 'scope probes, I was unable to measure the noise on the analogue output stereo connector, because the whole area of the Cubieboard was swamped with bursts of HF switching noise, generated by the Cubieboard itself. The noise was present when the Cubieboard was running, but the MPD app was not started. I even tried floating the 'scope and using two probes in differential mode, one to the ground plane, the other to audio signal, but I was still swamped by the HF clock noise of the A20, I think being picked up in the high impedance 'scope leads. I have NO idea how to achieve meaning full measurements of the noise floor for the ADC and audio output stages! All I can say it is a bl**dy wonder that MPD works as well as it does in that sea of noise, Power supply noise is minor compared with the SOC electrical noise. I will try to find the proper method of 'scoping SOC boards, the literature must be out there somewhere. cheers Patrick -- View this message in context: http://voyage-linux.34677.n3.nabble.com/Cubieboard-2-and-MPD-and-NO-external-DAC-tp4025840p4025854.html Sent from the Voyage Linux mailing list archive at Nabble.com. _______________________________________________ Voyage-linux mailing list [email protected] http://list.voyage.hk/mailman/listinfo/voyage-linux
