I have been trying to find information how do management pins function on Toradax SMARC iMX8M Plus Module. The list of pins I am interested in is specified bellow:
Watchdog pin(chapter 3.19 in SMARC 2.2 Specification)
WDT_TIME_OUT#
Management pins (chapter 3.21 in SMARC 2.2 Specification)
Since I can not find any info about this MCU in datasheet, I am assuming that this MCU runs some proprietary firmware. So I guess there should be documentation explaining how exactly the MCU drives all the before mentioned signals.
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Based on the SMARC iMX8M Plus datasheet, the management MCU handles several control signals as you’ve observed in the block diagram. Here’s what the documentation reveals about these pins:
Pin Assignments and MCU Control
The datasheet confirms that many of the management pins you’ve listed are indeed controlled by an MCU on the module(1). According to the pin assignment tables:
Boot Select Pins (MCU-controlled):
BOOT_SEL0# (P123) - 10kΩ pull-up resistor on module(1)
BOOT_SEL1# (P124) - 10kΩ pull-up resistor on module(1)
BOOT_SEL2# (P125) - 10kΩ pull-up resistor on module(1)
FORCE_RECOV# (S155) - 10kΩ pull-up resistor on module(2)
Management Pins (MCU-controlled):
RESET_OUT# (P126) - 100kΩ pull-down resistor on module(1)
RESET_IN# (P127) - 10kΩ pull-up resistor on module(1)
POWER_BTN# (P128) - 10kΩ pull-up resistor on module(1)
SLEEP# (S149) - 10kΩ pull-up resistor on module(2)
VIN_PWR_BAD# (S150) - 10kΩ pull-up resistor on module(2)
CHARGING# (S151) - 10kΩ pull-up resistor on module(2)
CHARGER_PRSNT# (S152) - 10kΩ pull-up resistor on module(2)
CARRIER_STBY# (S153) - 100kΩ pull-down resistor on module(2)
CARRIER_PWR_ON (S154) - 100kΩ pull-down resistor on module(2)
BATLOW# (S156) - 10kΩ pull-up resistor on module(2)
Unfortunately, the current SMARC iMX8M Plus datasheet does not provide detailed documentation about the MCU firmware behavior or how it specifically manages these signals. The datasheet notes and pull-up/pull-down resistor values indicate MCU control, but the specific firmware logic is not documented in the available sources.
For detailed information about how the MCU firmware handles these management signals, I recommend visiting the Toradex Community or GitHub to inquire about MCU firmware documentation or request additional technical details from Toradex support.
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Yes, some management pins on the Toradex SMARC i.MX8M Plus module are controlled by the onboard MCU, while others are controlled by the i.MX8M Plus SoC, as you can see in the module’s datasheet (Tables 9–10).
thanks for quick response. SMARC standard is strict in some cases and vauge in others. So if MCU runs proprietary firmware, than I need more clarification. If we begin with Boot Pins. SMARC standard specifies 3 boot selection pins(SMAR Specs 2.2):
