In a discussion with @Jornel a mistake in the SimpleFOCShield v1.3.3 has been found. This mistake will be present only for the boards that have date 11/2020 on the bottom side of the board.
The effect of this mistake will probably not be noticeable for most of you guys, but in some cases such as the link before, it could produce some strange behaviors.
The reason for this error is a broken part of the ground plane shown on the picture in red. While tracing the capacitor C4 I accidentally separated this small part of the ground plane and left it floating.
Effects of this error
Floating part of the ground plane in red, for less noisy power sources, will probably not produce any problems, for a bit noisier power sources can cause that during the initialization phase of the driver (the time after driver is powered up and before the MCU is configured ) some noise appears.
The noise is caused by random enabling/disabling motor phases since the pull-down resistor R2 is not actually connected to the ground. After the
pinMode(enable_pin,OUTPUT) is called in the Arduino R2 does not have any effect any more. The
enable_pin will be initialized either to
HIGH and pull-down job is done.
The capacitor C1 should not produce any problematic behavior because we have the bigger 100uF CAP1 smoothing the power supply voltage before it.
Finally the C3 capacitor not being grounded properly will not smooth the VREF pin of the L6234 which can lead to some runtime errors. And mostly due to the capacitor C3 I would advise you to modify the shield to resolve this issue.
Modifying the shield
If you do encounter some problems which seem to be related with this problem there is a very simple way to resolve it. On the picture below you can see in red all the ground pins of the L6234 and all the ground pads of the C1, C3 and R2.
Basically all you need to do is connect one red pad (either R2, C3 or C1) to one GND pin do l6234.
Here is an example connection. In my opinion the simplest ones to connect are C3 and the topmost GND pin of the L6234. So I’ve just cut a small peace of wire approx 1cm in length:
And soldered one side to the ground pin of the C3 and the other to the top left pin of the L6234.
Github repository update
Ok guys, I am very sorry about this error it is really a simple and stupid mistake but it happened. Anyway if you have any problems due to this error and if you are in any way unable to fix it please contact me directly and we will try to find a solution together.