Build MY own Arduino-controlled camera slider!

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Build MY own Arduino-controlled camera slider!

Post by megamaking » Mon Oct 16, 2017 7:30 pm

I watched this a long time ago.

Recently I've decided to design and build myself a new camera slider for my new Panasonic G7. yes influenced by Tom again, but I've checked the closest competition is the Sony A6300 which has a serve overheating issue so it is a big no-no for me.

I thought it was a simple project both coding and design-wise, but man... I was wrong, I spent days iterating the designs and I still feel unsatisfied with it. Coding wise, I am a programmer/software engineer but this is my first time playing with Arduino/programming an MCU. I found out that driving a stepper motor with Arduino library is a FPITA, there are so many issues with it.

Arduino built-in stepper class is too slow to do anything useful and worse of all, it is blocking the entire program when it is stepping, other than I also ran into a weird quad-stepping issue, where I need 4 times the steps to complete a full revolution. Even my math told me that I was right 360/1.8 * 16 = 3200, I ended up needing 12800 microsteps on an A4988 with 1/16 microstep enabled. The quad-stepping issue was fixed with another 3rd party library called AccelStepper but it is still way too slow.

I've ended up taking a glance at Tom's code, he was right about he is not a programmer ;) but I found a gem with his code and realized what he was talking about regarding the needs to drive the touchscreen and stepper motor fast enough... While I get a rough idea of Tom's code working, I don't quite understand some of the parts due to the messy structure of the code. I ended up driving the stepper with Timer1 interrupt, with some simple condition statements in the callback, the STEP signal is continuously generated until there are no steps left. I managed to achieve about 130mm/s with the new code with a fixed period/interval compared with like 20mm/s with previous attempts... That being said, I am still trying to play with it to find a more elegant solution.

It makes you appreciate how amazing the Marlin/GRBL optimizing is.

It will be great if Tom is willing to provide some inputs.


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