On Sat, 9 May 2020 23:33:40 +0530, in gmane.comp.hardware.beagleboard.user
Gattu Savanth <savanthgattu123-re5jqeeqqe8avxtiumw...@public.gmane.org>
wrote:
>Hi sir,
>so basically what i have done is i am unable to access gpio and pwm pins
>from adafruit python library.
>
To my knowledge, the BBAI does not permit run-time pin-muxing and
requires the pins to be configured using the u-Boot loaded device tree. The
Adafruit libraries probably assume BBB with run-time pin-muxing capability.
>so what i have done is pin multiplexing from the beaglebone ai survival
>manual.
>after pin multiplexing i have kept my servo signal pin in the P9_14 and i
>have tried to run the code in c language and there was small movements in
>motor and suddenly the beaglebone was switched off and from then onwards
>the board is not powering on.
>
Show use the code... Show us the wiring fully... Provide spec sheet for
the servo...
>*so that means my board has been damaged due to one pin*.How it can be
>possible.I have powered the servo from my 5v battery only i have just used
>P9_14 pwm pin thats it.due to this how the processsor will die.please what
>is the solution does repair is possible or what to do, i am really
>worried.the board is also quite expensive to buy again.I am very
>disappointed about the beaglebone ai.
>
I/O pins on the Beagles (all models) are limited to 3.3V (analog inputs
limit to 1.8V). If -- at any time -- your servo put 5V on the control line,
you have fried the processor. Lucky people may only fry the I/O buffer
circuit and the rest of the processor remains functional -- but a
significant 5V shorted to an I/O pin could do anything to the chip --
especially if it did not go through some sort of resistor network (5V at a
fraction of a mA might kill the pin, 5V at power-supply 1+A will kill it
all).
Granted, a decent servo shouldn't have feedback from V+ on the control
signal pin, and may even function when the power is 5V/GND with a 3.3V max
control signal (since position is by ratio of high/low, so long as the 3.3V
high is above any internal threshold
https://aishack.in/tutorials/servo-motors/ the pulse comparator should work
[Interesting... I'd been thinking the comparator may have just relied upon
integrating the PWM signal into equivalent voltage, and comparing that
voltage with the output of the potentiometer itself])
FYI, the earlier question was not "are you using an SD card to boot"
but was a request "will the card boot if you use an SD card instead of the
eMMC".
--
Dennis L Bieber
--
For more options, visit http://beagleboard.org/discuss
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