3 Replies Latest reply on Aug 17, 2015 6:35 PM by CMata_Intel

    Custom PCB + Edison Mini Breakout: I2C problems + Edison Rebooting

    martinianodl

      Hello,

       

      I built a PCB with some I2C ADCs (ADS1015) and a I2C Multiplexer (PCA9548) all of them connected to level shifters (PCA9306). I changed the schematic available at Sparkfun because I need more analog ports and I had to embed everything in one single board. I solder all the components and also the Edison mini breakout on the board and everything looks perfect.

       

      When I booted up a brand new Edison with the old firmware it gave me some warnings about the I2C but everything was fine until I configure the WiFi. During the configuration the Edison restarted. In order to try to solve this problem I updated the linux to the newest available at Intel's website and now during the boot it shows me the I2C warnings but it doesn't start the linux, it keeps reseting forever.

       

       

      I'm trying to figure out what is going on and I found a problem on my ADC schematic (see figure attached), where I'm connecting all the I2C outputs (HV_SCL and HV_SDA) of the ADCs to all four the level shifters. I don't know if it can be the problem.

      MainBoard Edison.png

      I hope someone could help me because I'm stuck with this problem and I can't test the components without this board.

       

      Thank you very much!

       

      I'm also attaching a picture of the board so you guys can see how everything is hooked.

      IMG_2465.JPG

      IMG_2467.JPG

        • 1. Re: Custom PCB + Edison Mini Breakout: I2C problems + Edison Rebooting
          CMata_Intel

          Hi martinianodl,

           

          How are you powering the board (Which pin/port are you using and how much voltage)? I have seen this behavior before when the board is having issues with the power lines. For example when it is being powered by a battery or a deffective USB port.

          If you use the breakout board with the Edison (without your custom PCB) are you able to boot the board?

          Try to flash the board with the flashall script

          This is in order to discard an issue with the power or the module.

           

          Now, if everything is working fine without the custom-PCB and you think that the bus with the output from the ADC's is giving you problems you can start trying to debug these lines.

          Are you getting noise from these lines?

          Which pins of the Edison are directly connected to the PCB? Are you testing the signals in these pins?

          I saw you are using GP19 and GP20 are you using something else?

          Are you using the same supply to power the ADCs/multiplexer and the board?

           

           

          Kind regards,

          Charlie

          • 2. Re: Custom PCB + Edison Mini Breakout: I2C problems + Edison Rebooting
            martinianodl

            Hi CMata_Intel,


            How are you powering the board (Which pin/port are you using and how much voltage)? I have seen this behavior before when the board is having issues with the power lines. For example when it is being powered by a battery or a deffective USB port.

                A: I'm powering the board with 2 Lithium Ion Polymer Battery - 3.7v 2500mAh using this circuit (Fast Multi-Cell Charger | Multi-Cell LiPo Charging | Adafruit Learning System). The Edison is powered using 7.4 on the Vin pin (J17 pin4).

                      I powered the Edison and the Board from an external power supply using 7.4v and it still reseting I also realize that is draining 0.67A while booting.

             

            If you use the breakout board with the Edison (without your custom PCB) are you able to boot the board?

                A: I soldered the breakout board on my board (I can't test with this one) but I have a spare that is working perfectly with the same Edison. It shows the I2C warning but it boots up.

                      The breakout board without the sensor is draining 0.12A during the boot.

             

            Try to flash the board with the flashall script

                A: I flashed using the Phone Flash Tool Lite and I will try using this one later.

             

            Now, if everything is working fine without the custom-PCB and you think that the bus with the output from the ADC's is giving you problems you can start trying to debug these lines.

            Are you getting noise from these lines?

                A: I'll debug the board today and try to send some feedback in the afternoon.

             

            Which pins of the Edison are directly connected to the PCB? Are you testing the signals in these pins? I saw you are using GP19 and GP20 are you using something else? Are you using the same supply to power the ADCs/multiplexer and the board?

                A:So, I'm using just a few pins of the Edison:

            MainBoard Edison.png


            As I said I will debug today and send what I got this afternoon. I'm using just the GP19 and GP20 for the I2C.


            I'm using a LMS8117 to regulate the 7.4v to 3.3v. I'm also using the 1.8v from the Edison and the V_sys (5v) from the breakout board.

                      The 3v3 is connected to:

                          - 1 x PCA9548

                          - Pull-up Resistors for I2C

                          - 1 x PCA9306 (Vref2)

                        - 1 x SN74AVC (VccB)

                      The V_sys is connected to:

                          - 4 x ADS 1015

                          - 4 x PCA9306 (Vref2)

                          - Pull-up Resistors for I2C

                      The 1.8v is connected to:

                          - 5 x PCA9306 (Vref1)

                          - 1 x SN74AVC (VccA)

                          - 5 x 10k resistor (button circuit)



            Thank you for the quick response!

             

            - Lucas Martiniano

            • 3. Re: Custom PCB + Edison Mini Breakout: I2C problems + Edison Rebooting
              CMata_Intel

              Hi Lucas,

               

              I apologize for the delay in my response, do you have updates in this?

              If you are using the VSYS line to power some of the components you could be having a problem with the current drained by this pin, the 1.8V should have pull-up resistors and being used for low current.

              Also, It's not necessary to connect the I2C lines to four different translators. If you use one it should work

               

              Kind regards,

              Charlie