6 Replies Latest reply on Apr 17, 2015 6:14 PM by CMata_Intel

    Minimum Voltages for boot

    Maaaah

      We have been bringing up a custom board and got some hiccups on boot. 10~11 seconds into boot there's a spike in current draw and the voltage drops 0.3~0.4 volts. I don't have a FTDI shield and usually ssh in after boot so I don't have access to the log file to see where it stops. Has anyone plotted the voltage/current over boot. The hardware guide has a nifty Figure 7 of the cold boot sequence, but not a lot of it is broken out to test points from the hardware. I believe the documentation says that Edison will boot at 3.15 V, ours boots at 3.5V.

       

      thanks,

       

      j

        • 1. Re: Minimum Voltages for boot
          CMata_Intel

          Hi Maaaah

           

          Have you check the debug message with:

          root@edison:~# dmesg
          
          

          Are you using the Release 2 Image or are you using a custom image?

          Also, how are you powering the Edison Module? Are you using a reference from Section 5 or are you using your own configuration?

           

          Regards;

          CMata

          • 2. Re: Minimum Voltages for boot
            Maaaah

            Thanks for the quick reply,

             

            This is using Release 2. We have our own configuration with multiple batteries, so I can't say that it looks similar to any of the suggestions from Chapter 5. It'd be nice to see the current draw timed to the boot sequence. I don't have the equipment at my disposal, I can only write down the times and the current drawing from the DC supply or a fluke.

             

            As for dmesg, all I can get is the last good boot sequence, after I've pulled up the voltage and ssh'd in. Are previous dmesg log's kept around somewhere? I looked in /var/log/ where I expect something like dmesg0 or dmesg.log to be and I couldn't find -name dmesg (other than the program).

             

            Thanks again,

             

            j

            • 3. Re: Minimum Voltages for boot
              CMata_Intel

              Hi Maaaah

               

              Take a look at this thread:Edison boot log (dmesg and friends) I think it will help you. Also have you tried with systemd-analyze?

              Have you tried to do measurements manually in the board?

               

              Regards;

              CMata

              • 4. Re: Minimum Voltages for boot
                CMata_Intel

                Hi Maaaah

                 

                Did you check the other thread? Do you have updates in this?

                 

                Regards;

                CMata

                • 5. Re: Minimum Voltages for boot
                  Maaaah

                  Hi CMata_Intel,

                   

                  Edison pulled past 400 mA at some point. We are using multiple batteries with swapping, so there's a low, but appreciable resistance that pulls a 3.5 V battery too low. It was not visible on the first image we were using. It is reproducible across the WW05-15 images. I haven't had the time to track what causes such an enormous draw, I did see the SPI light up right as it would spike. That's all I can say.

                   

                  j

                  • 6. Re: Minimum Voltages for boot
                    CMata_Intel

                    Hi Maaaah

                     

                    The draw of 400mA is an expected behavior regarding to more functionality enable. If you want to reduce the power consumption, you can go back to Release1 image. Another option is building a custom image and remove the recipes you don't need. By design Yocto is very configurable for embedded systems and can be customized for the lowest memory, power, drivers, etc.

                     

                    Regards;

                    CMata