![]() ![]() ![]() In any case, a USB breakout would be useful. But you could test it that way and, if it works, solder in a couple of diodes to isolate the power supplies from each other. That's a little dangerous because someone might accidentally connect things up with an unmodified USB cable, causing the host's and device's power supplies to fight. ![]() One trick would be to use a USB cable with a cut VBUS wire, and then solder a jumper from your board's +5V to where the VBUS wire would have gone. I suppose it's also possible that the board designer uses the USB bus voltage to detect if the device is connected to a host. Works with any 1.5Mbps (low speed) or 12Mbps (full speed) USB device. For a low-speed device (almost certainly not yours - this is mostly used for legacy keyboards and mice), the USB D- line should be pulled high. This handy little lowcost USB isolator is exactly what you need to provide protection against harmful noise, ground loops, surges, and spikes. For a full-speed device (likely what you have), the USB D+ line should be pulled high with no USB cable attached. If the USB microcontroller they are using is getting power locally, off the top of my head the only thing I can think of that might go wrong is if they are using the bus voltage for the speed identification pull-up resistor. What exactly are you seeing that is making you want to use an isolator? Properly designed USB devices that are self-powered should be able to remain connected to a powered host (such as the RPi) without issue, whether the device is powered on or not. You should contact the printer's manufacturer and see what they suggest.Īpart from all of the above, I have to ask why you are having problems at all. If it also supports high speed, then you may need a way to force it down to full speed. USB devices negotiate speeds, so if your 3-D printer only supports full speed USB, you should be fine using the isolator and an RPi. Nothing will break, but you might get error messages. I don't know what will happen if the devices try to talk to each other at higher speed, but I doubt that the isolator handles the situation gracefully. Note, however, that the isolator only supports full speed USB data, not high speed: your data speeds will be limited to 12 Mbps. If this isolator is placed between the RPi and the printer, then neither will see each other's power supply. Best of all, this USB isolator even has its own isolated 5V power supply that can supply 100mA, making it perfect for your BitScope Micro USB! Protect your computer or laptop, use one of these in between your ports.Are you saying that the 3-D printer is connected to a Raspberry Pi via USB and that you want to isolate the power supplies of the two devices while allowing the USB data to flow intact? This device is designed to do exactly that. It was roughly the same price, has a higher speed, and serves a useful alternative function. ![]() It is particularly useful when paired with USB testing instruments, you need to separate or isolate your eath ground (thru the USB connector to the computer to the power plug) from your circuit for high voltage, accident-protection, or floating ground needs. I was looking at buying a USB Isolator however, I ended up buying a powered four port USB 3.0 instead. Not for high speed USB devices, often used for video cameras (check your product to make sure its low/full compatible) Based on Analog Device's USB isolators This handy little low-cost USB isolator is exactly what you need to provide protection against harmful noise, ground loops, surges, and spikes. Have some USB logic analyzer, multimeter or oscilloscope and bumping up against the frustation of a shared earth ground? The Offspring (known for being electrical engineers) wisely sang "Ya gotta keep'em isolated!" Power and signal isolation improves common-mode voltage, enhances noise rejection, and permits two circuits to operate at different voltage levels. ![]()
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