Hello all,
I have a small device that has a SPI interface. My goal is that a user can communicate with the device via usb. An easy solution would be to use an arduino board between device and the user.
The problem is now that the device needs sometimes around 600ma/3.3v and I don't want to use an extra power supply for this.
My solution would be to use an arduino due that has a max current of 800ma via 3.3v pin and the user can power the board by using the usb 3.0 port of his computer.
Would that work or are there any other boards that I can better use for this project?
It would be nice to find a board that is not that huge as the arduino due.
Thank you
You say you don't want to use an "extra" power supply but you haven't said what the specification of the existing power supply is or why your "device" has to be powered from the Arduino.
Steve
You can use a 2nd USB port and a 3.3V LDO - just like external harddrive cases did some years ago.
Get an empty phone charger case that has two usb ports.
Rewire the board to pass power but to also conneconnect to the arduino.
@slipstick
The device is running at 3.3v. That's the reason why it has to be powered over the microcontroller or an extra 3.3v power supply. I want to avoid that extra power suppy because it would be not very user friendly. My idea was to power the whole thing over one usb 3.0 port.
@zwieblum
Do you have an example for these external harddrive cases?
@dave-in-nj
Thanks for the tip.
@all
Is there any reason why my solution with the arduino due would not work?
It's casings like this Neuhold Elektronik die Fundgrube für den Hobby-Elektroniker 6,35 cm (2,5") Festplatten-Gehäuse USB 2.0 zu IDE - you find them virtually everywhere. The usb cable has 2 USB-A plugs, so that sufficient current could be drawn for the hdd.
Thosty91:
I have a small device that has a SPI interface. My goal is that a user can communicate with the device via usb
No, if your Device has a SPI interface, the device will communicate thru the SPI protocol, right ?
BTW the DUE has a USB 2.0 peripheral (the Native USB port).
Thosty91:
The device is running at 3.3v. That's the reason why it has to be powered over the microcontroller or an extra 3.3v power supply.
USB provides 5V, so that a 3.3V converter is definitely required. You need an extra power supply if the 3.3V on-board regulator of whatever board can not supply the required current.
@ard_newbie
Yes, the device will communicate through the SPI protocol. That's the reason why I want to put an arduino board between the device and the user's computer.
Device <---SPI---> Arduino <---USB---> Computer
Ok, I understand the arduino due only delivers 800ma when powering over the power jack, right? Otherwise when powering over usb the max current is probably 400-500ma.
Which data sheet did you read for which board?
Sorry, there is no public data sheet for the device at the moment.
Arduino Due:
https://forum.arduino.cc/index.php?topic=560362.0
I think we can close the topic here. There is no way without an extra power supply or a second usb port.