I found this arduino nano shield. Before buying I would like to know your opinion is this will work and how is different from the sangaboard.
This looks a lot like v2 of the Sangaboard. Good spot! I would have thought it could be made to work, though the pinout may be different, so it might require some modification of the Arduino firmware to use the right pins for the motors.
The ordering of the pins within each motor may or may not be the same, but the three motors map to the same 12 digital outputs we use for the Sangaboard. So it’s possible you won’t need to change anything
It uses the same Arduino pins as the Sangaboard, but it does appear to be in reverse order for each motor. That probably just makes them rotate in the opposite direction if anything. There is a direction reverse software button in the web app anyway.
It is not clear how the 5V power for the motors is derived on that board. At first sight it is 5V taken from the Arduino, which would not provide sufficient current. There is no separate motor power pad visible. There is a 5V and GND on the lower connector, so it would at least be possible to remove the pin from the 5V output of the Arduino so that it does not connect to this board, then supply 5V for the motors to the 5V and GND pins on the edge of this board. It may be that the motor power is connected to VIN, which should be OK. Providing 5V on VIN on the board when the Arduino also has power from the USB connection to the Pi should not be a problem.
These are screenshots of the driver shield. more Information here. I think you are right. the 5v is coming from the USB. I could just cut the 5v cables from the stepper motor and use the external power source.
Wiring to each motor separately might be a bit of a pain. I would get a board and have a look at where the traces go on the underside, there is almost certainly a way to get an external 5V to feed the three motor sockets.
The developer just confirmed that is possible to connect external power to the 5v pins like this. Wondering what happens if I draw the power from the Rpi 5v pin. Need to experiment. Shipping coming on Thursday.
Hi @dgrosen I’ll be excited to see how you get on - if it works, it’s a much neater solution than the current nano-plus-three-boards version and I suspect others will want to order it! If the motor wiring is backwards, we should be able to figure it out in the firmware easily enough - do ping me and we can figure it out. It may actually just mean that the motors turn in the opposite direction; that wouldn’t need a firmware change at all, and should come out when you run the auto calibration.
I don’t recommend powering the motors from the Pi’s 5v pin, there is a real risk of messing with the Pi’s power line and blowing a fuse. It’s probably not terminal, but it will get pretty annoying I think, as you might cause the Pi to restart or get glitchy. I have, in the past, split the power from a reasonably over-specced 5V power supply (one of the offical Raspberry Pi ones) so that it powers the Pi and the motors in parallel (this means you don’t go through the polyfuse on the Pi, so there’s no risk of tripping it out), but that results in messy wiring. The Sangaboard v4 uses the 0v and 5v pins on the Pi to supply power, which should work neatly - but carries a significant risk that if you get it wrong, you blow up the Pi. I wouldn’t recommend that to anybody wiring it up with jumper wires, we only do it with the Sangaboard because it’s “HAT” shaped and thus quite hard to connect incorrectly.
So, if you can, separate power supplies are best - if you can’t it’s best to split it before the Pi. If you do try powering it from the Pi and don’t have problems with under-voltage, I would be very happy to hear about it! I suspect it’s relatively unlikely that doing that will destroy the Pi - but it’s moderately likely that you’ll trip the polyfuse and need to wait for it to reset.
I’ve been testing this shield for 2 weeks now and works fine. It is powered via the USB cable only. So far no fuse destroyed, no under voltage detected, no overheating either.
If this holds up is a good solution for me. I broke even with the upgrade, The official Rpi power supply is $7.99 and the Driver Shield $7.99 when you buy 4 of them. Furthermore, I got rid of a power cable and dont have to do the nasty wiring between the Arduino and the stepper motor drivers. Is a win, win, win for me
result! Well done. I imagine there will be a bunch of people who want to follow suit Have you figured out a nice solution to mount it in the base?
I forgot to take pictures before assembling. I used the new OFM box and modified the drawer to accommodate the shield. Nothing elegant. There has to be a better way. Added a support column, some support on the wall and moved the USB hole up. The screw holes are so small that I decided to use my hot glue gun to keep it in place. It works
drawer for driver shield.stl (219.9 KB)
I would love to buy some of these arduino motor shields, but it doesn’t look like the ebay seller ships internationally. Does anyone know where else these can be sourced? Thanks in advance!
The link took me to eBay in the USA. That is where I bought it and got them in 3-4 days. You can contact the company directly and ask. They replied to me on the same day.
Electreim (https://www.electreim.com/) seems to be an individual in the US and makes just a few boards of this type.
The ebay listing has only US as a shipping option, but does say contact seller for other shipping options.
Thank you! They wrote back quickly and made shipping to Canada available.
By the way, I will appreciate any better idea how to position the shield inside the box
The positioning looks good to me . Hot melt glue is remarkably common in fixing for electronic components. Without any sensible holes in the board you would need to have some complicated clamp to do much better than hot melt glue.
@dgrosen could you share your modified drawer? Posting it here is probably easiest…
The STL is at the bottom of the post with photos in, except that it seems to be missing the ‘tower’ clip on the side away from the ports.
By powered using only USB is it only using the cable connecting to the Arduino to the Pi?