Pick and place machines are a wonder to behold, as they delicately and accurately place part after part. Unfortunately, they have to have a similarly wondrous price tag. Luckily, they aren’t too difficult to make yourself as they share many properties of a 3D printer with some extra constraints. [Stargirl Flowers] released Starfish, an open-source pick-and-place control board based around an RP2040 to help people make their own.
She purchased a LumenPnP, and the itch to tinker became too much to ignore. The STM32 on the stock controller also happened to get fried, leaving an obvious opening to create a custom board. [Stargirl] chose Trinamic TMC2209 motor controllers to drive the three stepper motors. The power circuit is impressively overbuilt with a 3A fuse, a TVS diode for shunting voltage spikes, a P-channel MOSFET for reverse polarity protection, a low-pass filter for AC ripple, and a large 100μF capacitor.
The RP2040 is a good choice since it’s easy to get and has plenty of digital I/O. USB connects the board to the outside work and includes ESD TVS diodes to protect the board when connecting and disconnecting the USB port. Motors for vacuums are controlled by a 74HC2G34 buffer that drives enable lines to two MOSFETs. Solenoids are similar but with a high current peak and a much smaller current to keep them open. The DRV120 fits the bill as it is a single-channel relay with current regulation. I2C vacuum sensors are the same ones on the Lumen motherboard; they just required an I2C multiplexer.
It’s an extremely well-documented project explaining why each part was chosen and why. If you want to create an RP2040 project that needs to last, we consider this a guiding star. It’s all up on GitHub for you to take a look at.
This isn’t the first time we’ve seen RP2040 as part of a motor controller, and we suspect we’ll see more.
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