The following table contains known issues, scheduled bug fixes, and feature improvements for the Ixora Carrier Board.
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Customer Impact: In the off state, there is a potential backfeeding from the pull-up resistor of the WAKE1_MICO# signal on the carrier board to the Apalis SoM/SoC. However, as the pull-up resistor has a value of 10kOhm, the backfeeding current is small (up to 0.33mA). Therefore, there is no real impact expected.
Description: The WAKE1_MICO# signal is used to wake up the Apalis SoMs from the suspend state (sleep state). This signal is served with a regular GPIO (with wake capability). The IO rail of this GPIO is turned off during the off state. Therefore, by design, it is not possible to use the WAKE1_MICO# signal for waking the SoM up from the off state (the SoM can only be woken up from the off state by asserting the RESET_MICO# signal or via a complete power cycle). In the affected HW versions of the Ixora, the WAKE1_MICO# signal is pulled up to the 3.3V (always-on) rail. The 3.3V (always-on) rail remains on, even if the SoM is shut down (off state). As the IO rail of the GPIO pin serving the WAKE1_MICO# signal is turned off during the off state, a small backfeeding current can occur in the off state from the pull-up resistor on the carrier board into the SoM/SoC. For the above reasons, it is recommended to pull up the WAKE1_MICO# to the 3.3V_SW (switched), which is turned off in the off state.
Workaround: The 10kOhm pull-up resistor on the carrier board (R146) can be removed, if the related internal pull-up resistor of the SoC is enabled or the wake function is entirely disabled. This eliminates the potential backfeeding over the WAKE1_MICO# signal.