Reference Manual

The Digi Microcontroller Assist™ hardware
ConnectCore® 8X System-on-Module Hardware Reference Manual --
Preliminary
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If ‘wait for power key’ (W4PK) is chosen, the module will wait for a PWR_IO press before entering in
ON state when power is applied.
ON/RUN mode
In this mode, the PMIC is running at full power so all voltage regulators are generating the nominal
voltage for this mode. The CPU reset line is de-asserted and the processor is running at normal speed,
performing DVFS if the system was configured to do so. In this state, the SCU_PMIC_ON_REQ line is
asserted high, indicating that the module is ON.
Note that the specific state of the regulators (on/off) and the voltage in this mode are controlled by
the firmware running on the i.MX 8X processor. The PMIC starts with the default settings configured
on the OTP area, but once the software takes control itapplies the specific configuration
implemented in the firmware.
SUSPEND mode
The suspend mode (also known as suspend-to-RAM mode) is the low-power mode that allows the
module to preserve RAM content. When the module enters SUSPEND, the following actions take place:
n The processor goes into low power, disabling as much functionality as possible and keeping
active only the peripherals configured to wake the system from SUSPEND.
n The DDR memory is set to self-refresh mode to preserve its contents while reducing power
consumption.
n The PMIC goes into standby mode, configuring the regulators for this specific mode.
n The MCA goes into sleep mode, keeping active the peripherals that always run in low power
modes (like the RTC) and those configured to wake up the system (such as IRQs and power IO).
MCA GPIOs configured as outputs also keep their value.
OFF mode
The module enters OFF mode after a power-off event. In this mode:
n The PMIC is set to the OFF state and all the voltage regulators, except VSNVS, are switched off.
n The SCU_PMIC_ON_REQ line is asserted low, indicating that the module is in OFF state.
n The MCA goes into sleep mode, keeping active the peripherals that always run in low-power
modes (like the RTC) and those configured to wake up the system (such as IRQs and power IO).
COIN-CELL mode
In COIN-CELL mode, only the MCA is powered from the coin-cell battery, leaving the rest of the module
power inputs switched off. In this mode, the MCA remains in sleep mode, updating the RTC and
monitoring the following events:
n Tamper events that would be registered in the NVRAM memory of the MCA and would assert
the Tamper output if enabled.
n Power in MCA_VIN_DET, which indicates that power is reconnected to the system and it can be
powered-on.
Power IO signal/Power button
The MCA provides a signal (PWR_IO) to detect external events that trigger a transition between the
different power modes described in Power modes. The pin has wake-up interrupt/event capabilities, it
is active low, and it does not provide an internal pull-up. (The pull-up resistor, typically a 100K resistor
to VCC_MCA, must be added externally.) This signal is ideal for connecting a power button or the
output of a peripheral that controls the power state of the module and its transitions. The firmware