9 Replies Latest reply on May 9, 2016 11:52 AM by Intel Corporation

    ID Pin Logic Level?

    ryansturmer

      What is the voltage level for the USB_ID pin on the Edison?  Is it pulled up internally to the 1.8, 3.3 or other voltage?

        • 1. Re: ID Pin Logic Level?
          Intel Corporation
          This message was posted on behalf of Intel Corporation

          Hi,

          Are you looking for the electrical ranges of the IC? If you do, take a look at:
          http://www.ti.com/lit/ds/symlink/tusb1211.pdf
          http://www.intel.com/content/dam/support/us/en/documents/edison/sb/edisonmodule_hg_331189004.pdf 

          If this is not what you are looking for, please let us know more about your request.
          Which expansion board are you using? Are you building a custom board? 
          If you want to know the USB_ID voltage in a specific stage of the schematic, please let us know.

          Regards,
          Charlie

          • 2. Re: ID Pin Logic Level?
            ryansturmer

            More specifically,

             

            In order to specify the "OTG Mode" of the USB, the USB_ID pin at the 70 pin hirose connector on the edison must be grounded externally.  This pin is pulled up internally to the edison, I assume, but to what internal voltage?  The TUSB1211 datasheet specifies the OTG ID pin maximum voltage as 5.25V, but what logic level is this pin pulled to by the edison? (Ie, if I measured the USB_ID pin on the 70 pin hirose connector with the edison powered, but nothing else connected - what voltage would i expect to see?  1.8V, 3.3V, 4.5V, 5V?

             

            -R

            • 3. Re: ID Pin Logic Level?
              Intel Corporation
              This message was posted on behalf of Intel Corporation

              Hi,

              If you measure the USB_ID pin on the 70 pin hirose conector, you should get 0V. The TUSB1211 is inside the Edison Module and there is no access to it.

              Regards,
              Charlie

              • 4. Re: ID Pin Logic Level?
                ryansturmer

                If grounding the USB_ID Pin is what puts the Edison in "OTG" mode - how is it possible that when the pin is floating, that the voltage on it should read 0V?  Shouldn't that pin be pulled up internally to some logic level, if dragging it down externally produces a software effect?

                • 5. Re: ID Pin Logic Level?
                  Bunsen

                  I measured this a while ago.  It is pulled up; if I remember correctly it's pulled up to 1.8V.  I don't have an Edison in front of me to check, but I can take a look when I get home tonight.

                   

                  Also, I see Intel has graduated from simply not telling customers anything useful about Edison to actively misleading them.  Way to solidify your position in the IoT market, guys.

                  • 6. Re: ID Pin Logic Level?
                    ryansturmer

                    LOL!

                     

                    That makes sense, I guess - I resorted simply to using an open drain buffer to drive the pin for my application, which has a voltage range that goes down to 1.6V - hopefully that covers all my bases!

                     

                    Thanks!

                    • 7. Re: ID Pin Logic Level?
                      Farit

                      While measuring,

                      1. was the USB chip inside of the Edison module selected and active or was it in the suspend mode with the pins in the tri-state mode?

                      2. what was the VBUS voltage?

                      3. what was the OTG_CTRL USB chip register setting for IDPULLUP? Was it disabled, weak pull-up, strong pull-up?

                      • 8. Re: ID Pin Logic Level?
                        Bunsen

                        I believe the USB PHY is active; I'm measuring with the Edison running normally.  VBUS is connected to nothing at the moment.  I have no idea what the PHY's internal registers are set to; that's being handled by, um, probably the linux kernel.  Since it's running and the system responds to grounding USB_ID by changing its USB behavior, I would have to assume that the IDPULLUP bit of OTG_CTRL is enabled.

                         

                        For the record, I measured my board and found USB_ID pulled up to 3.3V, not 1.8V.

                        • 9. Re: ID Pin Logic Level?
                          Intel Corporation
                          This message was posted on behalf of Intel Corporation

                          Hi guys,

                           

                          The TUSB1211 is inside the Edison Module and there is no access to it, with this I mean that you can’t physically see the IC.
                          I’m measuring the USB_ID by doing the following:
                          Using the Arduino Expansion Board, there is access to the 70 pins from the Hirose Connector, you need to use the TP pins. Take a look at the following schematic:
                          sc.png
                          The USB_ID is the TP4. You can measure the voltage in this pin. By using the microswitch, you can set the board to work as host or device, while working as a device the voltage is 3.40V ~ 3.39V and as a host 0V.  This measurement was made by using the Edison on its normal state (S0), and with the USB-OTGport connected to a PC, the VBUS (TP18) is 5V unless the USB is not connected and enabled with the microswitch; without the USB connected, the measurements for ID_PIN remains in the same values.

                           

                          Regards,
                          Charlie