SkeptoLogic

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  1. On Windows, and on the original board, it always showed up as two, one that is used for the JTAG and one that is the serial port. It looks like something on my PC changed and it is only showing up as one for new boards. I traced the difference down to a setting on the USB controller A not having a "Load VCP" box checked in the advanced tab. If you are seeing only one comport, than it may be my original settings that were wrong all along.
  2. I have 3 basys3 boards, one I have used for some time, and two brand new. When I plug the new units in, the JTAG serial port shows up, but the user serial port does not show up. Switching back and forth between the new boards and the old board is consistant, and all using the same cable ( and I tried another cable that was included with a Xilinx board). The old board always has two ports, and the new boards both have only one. All boards show up with the USB Serial Device A, and USB Serial Device B under the USB controllers in device manager. The Hardware IDs for both A & B perfectly match between boards. The one serial port that does show up under Ports in device manager has the same hardware IDs that the B device has. The A device is not instantiating a serial port. In a desperate attempt to fix the issue, I turned on "view uninstalled devices" in device manager and uninstalled all digilent devices. Now all three boards have only one serial port enabled. Any ideas as to what could cause this will be appreciated.
  3. I am using the PMODAD5, and was trying to get bipolar results out. My settings are config = 0x840150 for bipolar, and 0x840158 for unipolar, and mode = 0x080402. I assumed the U/B* bit in the config register would control the data format, linear or "unipolar" vs 2s compliment or "bipolar". I expected that with a 2.5 volt reference, and about 2.5 volt input signal, that unipolar would result in numbers close to the unsigned mid-scale, like a lot of numbers around 7FFFFF and 800000, and that the bipolar setting would yield 2s complement versions of the same values, so I would get a lot of numbers around 000001 (+1) and FFFFFF (-1). Instead I found bipolar mode gives me unipolar numbers around zero like 800000 and 7FFFFF and unipolar mode gives me half zeros, and half small numbers like 000001. The data sheet is very vague on this topic and does not describe the encoding at all, so I have had to make some assumptions on what this does. I am hoping that others can confirm similar results or provide a better explanation of the control bit than is provided in the data sheet. Note: I am seeing numbers much greater than +- 1, but simplified this for the explanation. The numbers I am getting are +- 2^16, probably because the ADC is run off of my computer's USB power supply.