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6.3.3
Fan Control
The cBC uses the PWM (FAN_PWMOUT) signal to adjust the rotational speed of the fan without changing the fan’s input voltage. Additionally,
the FAN_TACHOIN signal provides the ability to monitor the system’s fan RPMs (revolutions per minute). For accurate RPM reading, the
FAN_TACHOIN signal must receive two pulses per revolution. Therefore, a two pulse per revolution fan or similar hardware solution is
recommended.
Note
1. Use a four-wire fan to generate the correct speed readout. For the correct fan control (PWMOUT, TACHIN) implementation, see the SMARC
Design Guide Specification.
2. PWMOUT and TACHIN pins are shared with GPIO 5 and 6 respectively. The conga-SA7 does not support fan control if these pins are used
for GPIO functionality.
6.3.4
Power Loss Control
The cBC has full control of the power-up of the module and therefore can be used to specify the behavior of the system after an AC power loss
condition. Supported modes are “Always On”, “Remain Off” and “Last State”.
6.3.5
Watchdog
The conga-SA7 is equipped with a multi stage watchdog solution that is triggered by software. The conga-SA7 does not support external
hardware triggering because the SMARC Specification does not provide support for external hardware triggering of the watchdog. For more
information, see the application note AN3_Watchdog.pdf on the congatec GmbH website at www.congatec.com.
Note
The conga-SA7 module does not support the watchdog NMI mode.
6.3.6
Enhanced Soft-Off State
The conga-SA7 supports an enhanced Soft-Off state (S5e)—a congatec proprietary low-power Soft-Off state. In this state, the CPU module
switches off almost all the onboard logic in order to reduce the power consumption to absolute minimum (between 0.05 mA and 0.09 mA).
Refer to congatec application note AN36_Enhanced_Soft_Off.pdf for detailed description of the S5e state
