FAN_0 not working?

  • According to the COM-HPC module schematics, the FAN_0 header should be controlled by the MMC - I presume according to the SoC temperature. However, I just tested it and despite getting up to over 80C the fan never started running. I've connected the module's fan to FAN_1 for now.

    Under Linux, 'sensors apm_xgene-isa-0000' displayed:


    SoC Temperature:  +87.0°C

    CPU power:        45.44 W

    IO power:         19.28 W

  • Hi Rebecca,

    Thank you for contacting I-PI forum. After I confirmed the hardware circuit design of  COM-HPC module, the fan signals provided by the module to carrier are optional design. The preset fan function is provided by fan header on top of the module. It need to do a rework on the module to provide the fan signals to COM-HPC carrier if customer need FAN_0 header could works.



  • @Rubio Tsao Thanks. What connector is used to plug into the module fan connection? It's much smaller than the headers on the carrier.

  • Hi Rebecaa,

    Please refer to the link of the module fan connection for your reference.

    vendor P/N:HW12-004-R0S-00
    Description:Wafer,4pin,Right Angle(90 degree),SMD,pitch=1.25mm, color=white



  • Luckily Rebecca gave me a heads up on this on Twitter, so I didn't make the same mistake. But I see that your getting started guides still indicate using FAN_0, and that should probably be fixed until you rework all boards going out. Would you mind revising it so others don't have problems? Thanks!

    I.e. step 4 here needs to be corrected:

  • I noticed the same, with the fan connected to FAN_0 it was not spinning and the module was getting warm. I moved it to FAN_1 and now it spins as expected.

  • @Olof Johansson Based on Ian's reply at I'm planning to create a few adapters to connect to the module's JST connector so if anyone wants one I can send one to them.

  • Hi Rebecca,


    As the current FAN_0 does not have a PWM signal due to an optional BOM on the module board, and only the module's BFAN_1 is activated in previous.

    The new BOM will activate both FAN connectors as FAN_0 on the carrier board and BFAN1 on the module.

    And we will be preparing a converter cable for all clients who have ordered the AADK/AADP to connect the FAN to the module's BFAN_1.

    For the converter cable usage:


    Before the cable arrives, we recommend plugging the fan cable into the following FAN connectors:


    FAN1, 2, with fan speed controlled by temperature as FAN table below.

    1 under 30 degree > 40%

    2            30 degree > 50%

    3            35 degree > 60%

    4            40 degree > 70%

    5            45 degree > 80%

    6            50 degree > 90%

    7            56 degree > 100% 


    FAN4, 5, with a 100% PWM output at all times.




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