HDMI out needs CEC, HPD and I2C?

    Hi, we are building a wearable router. Now a new customer requests came in asking to connect an external HDMI to AV converter. As the pins for HDMI_CEC, HPD, SDA and SCL are always reserved for both CAN interfaces, I'm wondering if this signals are mandatory to drive a HDMI device.


    Alternative would be to use the DSI_A interface, but then a DSI to HDMI bridge IC bus be added.

    The default pin settings are defined by our PicoCore "standard". Which means if you use the pins with these signals, then other PicoCores and also future PicoCores will be pin compatible. But of course you are free to use a different function, with the risk of losing compatibility to future modules. Which means we cannot guarantee this functionality on the same pins on other PicoCores.

    • HPD is actually rather important, as it detects if a cable is plugged in and a display is connected.
    • CEC is only necessary if you want to remote control other devices over HDMI. For example a TV can control a BluRay player (Play, Stop, Pause, Fast Forward, etc.) by sending appropriate commands via CEC.
    • SDA and SCL are also important to read the EDID info, i.e. the list of possible resolutions that the display supports. However the NXP driver can use any I2C port, so it is not too important to use exactly those two lines.

    If you want to use these HDMI signals, it is possible to use other pins for the original function. For example I2C_A (J1_4/J1_6) is also available on UART_A_RTS/CTS (J1_14/J1_16) or CAN_B (J1_4/J1_6) is also available on UART_D (J1_34/J1_36). So if you need any of the signals that are required for HDMI, send us an E-Mail with all your required signals and we can check if we find a matching pinmux setting for all your signals.


    Please note that HDMI/DVI output is a hardware option on PicoCoreMX8MP. You have to purchase the right variant (V3I or V3XI) to have HDMI/DVI at all. Also note that HDMI on this CPU does not support HDCP! However it does support ARC and eARC (also referred to as HEAC) on DSI_B_DATA3_P/N. As we only use the DVI part of HDMI, we may not have proper support for all the additional HDMI signals in our device tree. So you may need some extra work to get this running.


    Your F&S Support Team

    F&S Elektronik Systeme GmbH
    As this is an international forum, please try to post in English.
    Da dies ein internationales Forum ist, bitten wir darum, Beiträge möglichst in Englisch zu verfassen.

    Thanks for the very broad explanation.

    As we talk about video output, I'm curios if do you support DisplayLink on USB 2.0 and USB3.0. This could be another good option to get VGA, DVI and HDMI video outputs without using DSI or onboard HDMI. Will open another topic for DisplayLink.

    No, we do not support DisplayLink on USB. As far as I understand, this requires support from the hardware, so I believe this is not possible on NXP's on-chip USB ports.


    Your F&S Support Team

    F&S Elektronik Systeme GmbH
    As this is an international forum, please try to post in English.
    Da dies ein internationales Forum ist, bitten wir darum, Beiträge möglichst in Englisch zu verfassen.