6 POWER-ON SEQUENCE AND RESETTING
6.3 Treatment of pin GPIO
A few pins (PA 12, PA 13, PA 15, PA 25, PA 28, and PA 26) of the module will have
instantaneous high-level pulses before the chip fully works, and everything will be
normal after the chip works. For these pins, if they are directly used as driving light
sources or relays, in order to avoid the effect of burrs at the moment of power-on,
refer to the following processing:
Pull down a 1K resistor at an output port of a pin, and then connect a diode in series.
In this case, the voltage of a GPIO will drop to about 2.7V after passing through the
diode. The red box represents the original drive tube on the customer’s baseboard.
A diode D1 and pull-down 1-KΩ resistor need to be added.
If a lamp is directly driven, pull down a 10-KΩ resistor on the grid of the positive MOS.
If a lamp is not directly driven and a PWM signal will not be sent until the module is
officially launched, there is no need to add a pull-down resistor and diode.
If a relay is driven, you can change the diode to a resistor of 0 Ω according to the
actual situation.
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