Friday, September 22, 2023

[HIRING]: Staff DevOps and K8s engineers

Position Company Location Salary
Staff DevOps Engineer Achieve Arizona $160k - $190k
CNO Platform Engineer ManTech Remote $108k - $180k
Staff Engineer LeafLink Remote $200k - $230k
Senior Software Golang Kubernetes Engineer NVIDIA Florida $176k - $333k
Developer Success Engineer Temporal Technologies Remote $130k - $180k

The highest salary listing of the past week goes to NVIDIA with $333k!

Saturday, September 16, 2023

Why did I blow my L6219 Stepper Driver?

Hi all. I've been developing a circuit with bipolar stepper motor driving a gear system on a mount. The gearing shaft doesn't have full 360 degrees range so gets "caught" on the mount itself on both sides. I managed to get my code working to control it, but mistakenly set my delay time way too short, and the motor quickly caught on the mount and stalled. Shortly after the magic smoke came out of the L6219. This might be a basic question, but I just want to 100% confirm the reason for the driver blowing so it doesn't happen again.

According to its datasheet, the L6219 is current-controlled (I set it to 500 mA max), and also has thermal shutdown. Given that, I would have expected the thermal protection to kick in. However it also says it has a peak current of 1A. I'm guessing the very sudden stalling of the motor caused it's back EMF to vanish, thereby shorting the driver's output before it had a chance to implement protection and shut off the outputs? I think I initially assumed current-controlled also meant current-limiting, but I'm guessing now that's not true at all?

Then, as a side question, how would I be able to safely rotate the motor until it catches on the mount (so that I know where its starting position is)? Would I have to do this very slowly and use a current-sensing resistor? Or is there another way?

Why did I blow my L6219 Stepper Driver?

Hi all. I've been developing a circuit with bipolar stepper motor driving a gear system on a mount. The gearing shaft doesn't have full 360 degrees range so gets "caught" on the mount itself on both sides. I managed to get my code working to control it, but mistakenly set my delay time way too short, and the motor quickly caught on the mount and stalled. Shortly after the magic smoke came out of the L6219. This might be a basic question, but I just want to 100% confirm the reason for the driver blowing so it doesn't happen again.

According to its datasheet, the L6219 is current-controlled (I set it to 500 mA max), and also has thermal shutdown. Given that, I would have expected the thermal protection to kick in. However it also says it has a peak current of 1A. I'm guessing the very sudden stalling of the motor caused it's back EMF to vanish, thereby shorting the driver's output before it had a chance to implement protection and shut off the outputs? I think I initially assumed current-controlled also meant current-limiting, but I'm guessing now that's not true at all?

Then, as a side question, how would I be able to safely rotate the motor until it catches on the mount (so that I know where its starting position is)? Would I have to do this very slowly and use a current-sensing resistor? Or is there another way?