I'm trying to power the adau1701 miniz evaluation board from a power supply independent from the computer. I connect the power supply cords to the barrel jack instead of the battery input pins as I messed the soldering points at the battery input pins. When the switch is turned on, the light on the board is lit, indicating that the board is powered. However, the output signal is pure white noise.
When I turn the switch off, and power the board using the programmer board and the USBi, connecting the jumper, the light is lit and the program I compiled to the board is running.
From the data sheet, powering the board either by USBi or by battery should have the same consequence, however, in my case, the power supply from battery messed up with the board, while the USBi power supply does not.
Can anyone help me with this problem? I need the board to be powered by battery alone.
Here are the pictures of my project:
Also, here is the program I compile to the board:
I'm new to sigma studio, and therefore the setup is modified from the example given from the data sheet. Again, can someone please help me?
In my experience, white noise is caused by something corrupt in the compiled program. However, your board works fine when powered via USB so there's one other problem I'm aware of. Did you obtain your ADAU1701MINIZ board recently (in the past 3 months)? If so, power it down and measure across its resistor R6 with an ohmmeter. R6 is located near the power jack. It's supposed to be 78.6 K ohms (your actual reading might be 20 K -- 50 K with the parallel paths). If instead you read less than 100 ohms, then your board is defective. It appears a few went out with R6 at 78.6 ohms. The discovery was initially described in this thread. My recent ADAU1701MINIZ also had this defect, fortunately I work for a contract manufacturer so I had our "surgeon" fix it. R6 sets the output voltage of regulator U2; this voltage is too high with the wrong value.
Thanks for your reply! I did obtain this board on Jun-July-ish. After I inspect R6, it does has a resistance of 78.9 ohms rather than K ohms, so my board does have defects. This has been confusing me for weeks! Finally I got an answer for this. What would you suggest to fix it? I think I need to fix this board as well.
Inspired by your point, I checked all the resistors on the board and I found that there are still some more defects: R15 and R20 are measured as 8.06 k Ohms instead of 8.06 Ohms which they ought to be; R7 measured as 6.14 k Ohms instead of 140 k Ohms. I think this is a problem that happens to all the chips during these 3 months.
R15 and R20 are supposed to be 8.06 K:
R7 is nearly impossible to accurately measure in-circuit, especially when R6 is incorrect:
Thus, the only resistor you need fix is R6. The others were fine on my board and are likely OK on yours.
Now for how to get it fixed: So far us two with this problem had the resources to fix it ourselves. Unfortunately, where R6 is on the board makes it a challenge to change. The engineer that works with me is rather good with SMD soldering, but he looked at the job and recommended I engage our rework dept. to fix it instead! Edit: I just noticed DaveThib's reply below so you've got a way to have this taken care of.
If you do not have the capability of changing the resistor where you are in the University, then send the board to me and I will get it fixed and send it back to you. Just include a short description and your full mailing address and phone number in case we need to contact you.
Since you are in the USA this is all easier to do.
804 Woburn St
Wilmington, MA 01887-3494
The same goes for everyone else who has this issue. Just contact me first so I know about it.
This problem was caught and I did request that all stock be recalled but I don't think anyone who purchased these was notified. It was caught fairly quickly so there were not a lot sold. Sorry you happened to get one. We will get you fixed up.
Thank you Dave!
This reminds me when my first USBi proved defective and an ADI support engineer personally arranged its repair. This level of service gets remembered -- we're on our third SigmaDSP product design and counting.