I'm using the MKR motor shield since a while and one thing that i don't get solved is how to stop the motors spinning for a about 1 or 2 seconds when powering the shield. Since i'm using this shield for a robot with wheels its kind of annoying to hold the robot in my hands everytime i switch it on. I was already searching in the boot-loader of the shield (don't know if this is the right place to look for). So if anyone could point me out to where i can either comment out those specific lines or change some methods i'd really grateful.
Thank you very much!
This is caused by the activity of the boot loader, during that time all the pins are inputs and this can cause the pins to float and command the motors to run.
The cure is to fit pull down resistors of about 10K to each of the motor control pins. But in the case of a motor shield there should be an enable pin for the whole controller, so this must be pulled down ( or high depending on the shield’s circuit ).
Can you get the schematic of this shield as this is a design point that should have been addressed.
Thank you Grumpy_Mike for the help and fast response. Overall i really like this shield but i just can't get why this behaviour/functionality hasn't been adressed right out of the box. I can image numerious (if not almost all) usecases where you don't want to have motors spinning without any control right away after switching on. Besides the resistor-solution you've mentioned i was thinking about adding a mosfet-solution controlled by another controller. I'm not super experienced on that to be honest but it makes sense right?
Well you are still left with the same problem, that of pins that are meant to be outputs are fot a short time inputs.
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