Verdin iMX8M Mini Issue Tracker

Customer Impact: A sudden change in the computer module input voltage might involuntarily activate the CTRL_PWR_BTN_MICO# signal that, by default, will initiate the software shutdown or wake the system from the sleep state.

Description: The circuit used to generate the CTRL_PWR_BTN_MICO# on the computer module is affected by a hardware bug that could cause this signal to be triggered involuntarily by a fast change in the input voltage. The Voltage needs to increase immediately by at least by 0.9V to trigger the signal. The CTRL_PWR_BTN_MICO# allows the implementation of a power button behavior like the ones used on regular personal computers and smartphones. Short pressing the power button powers up the system from the “Module OFF” state or wakes the system from the sleep state. If the module is running, short pressing the power button generates a software interrupt. Depending on the operating system settings, this starts a software shutdown or opens a menu that lets the customer decide what to do.

Workaround: The best way to mitigate this issue is to configure the CTRL_PWR_BTN_MICO# differently in the software. If this is not possible and it is necessary to test the behavior of a module where this issue has been fixed, please contact the support team. Future versions of this product will have a different assembly option that will solve this bug completely.

Customer Impact: The voltage level of the PCIe reference clock output (PCIE_1_CLK_N and PCIE_1_CLK_P) is too low and not PCIe compliant. For some PCIe peripheral devices, the voltage swing is too small for those devices to operate properly.

Description: The PCIe reference clock available at the module edge connector pins 226 and 228 is generated by the i.MX 8M Mini SoC. The clock signals are unintentionally terminated twice. There are 49.9Ω termination resistors on the module, and the SoC pins have internal terminations as well. This double termination adds too much load on the reference clock, leading to a wrong output level. The V1.0B versions of the Verdin iMX8M Mini modules are not affected by this issue since those feature an external PCIe clock source that requires the external termination resistors.

Workaround: Remove the two 49.9Ω termination resistors R28 and R29 on the Verdin iMX8M Mini module. The resistors are located on the top side of the module. For more information, please consult Errata #14 in the Verdin iMX8M Mini errata document.

Description: It is not possible to turn off the power rails of the Wi-Fi and Bluetooth module after they have been turned on.

Workaround: After booting the module, turn on the power rails for the Wi-Fi and Bluetooth module only if the radio is required. Keep the rails turned on or reboot the system if the rails need to be turned off again.

Description: Due to back feeding, the CTRL_PWR_EN_MOCI can have a residual voltage. This means the voltage remaining at CTRL_PWR_EN_MOCI can be too high (>0.3V) which can be interpreted as a high state by some input circuits.

Workaround: Make sure the input low threshold for the circuits that are connected to the CTRL_PWR_EN_MOCI signals are high enough or use the CTRL_FORCE_OFF_MOCI# for disabling the power rails in power-off-state.

Description: The CTRL_FORCE_OFF_MOCI# is on the V1.0 module a simple GPIO with an on-module pull-up resistor. Depending on the carrier board, the power can get killed during reset cycle or the power down does not switch off the rails in the expected order.

Workaround: In order to be able to perform a reset cycle without killing the power, on the Verdin Development Board the jumper for the CTRL_FORCE_OFF_MOCI# needs to be removed (pin A23 and B23 of X6). On the Dahlia, the resistor R96 needs to be removed for the same purpose. However, this workaround will disable the kill feature of the carrier board.

Description: It is not possible to access the JTAG Boundary Scan mode. The JTAG strapping on the module is not correct. An incorrect JTAG ID is read back.

Workaround: Not available.

Description: During a reset cycle the CTRL_PWR_EN_MOCI signal can go to an undefined state. For some time, the signal can be neither high nor low.

Workaround: If a defined state of the CTRL_PWR_EN_MOCI is required during the reset cycle, use a comparator circuit.

Description: Missing pullup’s on CAN SPI MISO signals might cause signal flickering. This could result in unecessary higher current consumption.

Workaround: There is no software or hardware workaround available for V1.0 modules. A weak external pullup will be added to V1.1 modules in order to avoid the MISO signal to float.

Description: The dedicated reset input of the boot eMMC on the module is not connected to the SoC. Therefore, the eMMC can only be reset by a power-on reset.

Workaround: If the eMMC needs to be reset, a complete system reset needs to be performed which includes a power cycle that triggers the power-on-reset of the eMMC.