Missing jumpers for thermal sensors out of the box + Questions about other chassis connections

  • Hi,


    Finally got around to installing my dev kit into a 2U Supermicro case here (CSE-826A).

    I noticed that the BMC didn't get any temperature sensor readings, and after ssh:ing in, it was constantly logging:

    <132>  2023-09-03T19:51:43.321225-04:00 localhost IPMIMain: IPMIMain - -  [639 : 735 WARNING][hal_api.c:302]hal_api.c : sensor number = 10, sensor name = REAR_TEMP, error = 1 -
    <132>  2023-09-03T19:51:43.321225-04:00 localhost IPMIMain: IPMIMain - -  [639 : 735 WARNING][hal_api.c:302]hal_api.c : sensor number = 11, sensor name = FRONT_TEMP, error = 1 -

    Taking a look at the schematics, it seemed like P2 and P3 should both be jumpered between pin 1 and 2, but only P2 had that on my board. P3 had no jumper installed (so neither 2-3 nor 1-2 bridged).

    Was this just a fluke for my board, or do they not come preconfigured for the general use case one would expect?

    And, furthermore - what's best practices for connecting other components from the chassis? Things available are:

    1. Lid open switch -- I see pin 19 on the front panel connector, I guess between that and (far away) ground. Annoying to not have a ground pin right next to it. :(
    2. There are a handful of LED connectors on the front panel pin header, but a lack of corresponding VCC pins to connect the other leg to. How's that expected to work?! Also, per the schematics they're not NC, some of them are in use.
    3. Schematics and documentation diverges -- see screenshots below.
    4. Not sure what to do with the i2c bus from the power supply (I'm guessing it's for power measurements and/or redundancy readings). And, even if connected somewhere, I'm guessing MegaRAC needs to be configured to know what to do with it. Any guidance there?
    5. Case has an "OH LED" connector, which seems to be a multi-porpose one for UID as well as for fault alerting. I suppose I had to pick one of the functions since the carrier has them separately. I went with UID for now.

    I2C connector from PDU. Connector reminds me of the old 4-pin audio connectors on CDROM drives back in the day:

    I2C bus connector from PDU board


    Here are the two screenshots of documentation vs schematics:


  • Hi Olof,


    Good to see you there,

    For JP2/3, both pins 1 and 2 should be connected. Before proceeding, please check if any jumpers are included in the packaging box or bag.


    You can find more information about JP2/3 in the carrier user manual available at this link:



    Regarding the lid open switch, there is indeed a CASE_OPEN_N on pin 19, as listed. It's a GPIO pin connected to the BMC. However, its function is not implemented because the carrier does not have an LED or buzzer for alert purposes. This feature is intended for customized carriers only.


    For the front panel LED, there are positive and negative pins for HDD_LED on pins 8 and 10, and for the system power LED, we recommend using pins 1 and 12 of the GP_SPI connector. You can refer to the COM-HPC Server Base Front Panel Connection using the following link after downloaded:


    Also, could you please specify which LEDs do not require VCC in your reference?


    While the schematics are made by our R&D team to be as detailed as possible, we advise primarily following the user manual. Some N.C. (No Connection) points are included for R&D testing purposes only, and they should be left unconnected. These points will not affect the majority of chassis connections, as listed in the front panel pins section of the manual.


    Regarding the I2C pins, we apologize for not providing information in this thread. Could you please guide us to the specific page in the schematic or user manual where you are inquiring about the I2C pins?

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