I have several questions on piloting servos with Jetson nano GPIO and PCA9685.
Jetson nano 2 GB (powered with USB adapter, 5V, 3A)
Board PCA 9685 hat (not Adafruit brand, but like this one : https://www.amazon.com/Servo-Driver-HAT-Interface-Pi/dp/B07XD8SLY3) / It is using the power from the nano.
two servos (HITEC HS-422) for Pan and Tilt.
First look :
Yes, it seems to work pretty well (I use the Adafruit servo-kit library, with GPIO). Servos are moving etc …
variation = range(0,180)
for degree in variation :
But …. At the end one or two things were not going so well … I don’t really know why.
Maybe someone can help me to find out a solution.
First : I would like the servos to move from 0 degree to 180 degree … & its is more 150 degree than 180, why ? Is it due to the input voltage which is lower than 5V (equal 3,3 V on GPIO ?). HITECH Spec : input should be between 4,8 and 6). Not sure, or maybe servos are built like this, not able to reach 180° ?
Second … I tried to change the speed of the servos … using a step time of 0,001 in the loop instead of 0,01 and … it crashed the nano (direct shutdown, ouille !!!) … maybe too much power needed for the servos.
I saw that for piloting the « servos », it is better to use an additional power supply … but how ?? I tried … to plug power directly on the servos and it is not working at all.
Servo + pin connected to the « + » of an external power source (3 battery AAA)
Servo ground pin connected to the « - » of an external power source.
Servo Signal pin connected to the pin of PCA9685 (0 or 1)
On PCA9685, It is also possible to plug VIN/GND but in that case, should I also need to power the nano with USB adapter, 5V, 3A … meaning two source of power at the same time … not sure the nano will appreciate.
Because, if I only plug the VIN/GND on the PCA9685 (no other source of power even for the nano), it also powers the nano …
What should I do ?
I saw the videos on www.toptechboy.com (AI ON THE JETSON NANO LESSON 32: TRACKING AN OBJECT WITH SERVOS IN OPENCV but he is not using additional power supply for servos)
Thanks a lot, if anyone can help.