I was very frustrated with my failure to get the TMC2660 board variation running. I checked and double checked the connections, alas the steppers would not move at all.
I purchased one TMC2660-BOB kit from digikey and started experimenting with it, instead of my board. At first, I had the same failure – the stepper would not move at all. The software was a very simple Arduino sketch – what would be that wrong. Since the kit was designed by Trinamic, the hardware should be proper. Alas, no luck. I declared the TMC2660 chip cursed and moved to my soldering machine project.
Yesterday I decided to give the test jig one more try. After a few failed attempts. I spotted an error in the Arduino code – I was passing the incorrect CS pin in the driver setup. DUH!!! After a quick fix it was working.
Then I moved back to my original goal to test the thermal dissipation ability of my TMC2660 PrntrBoard design. I connected my board and started to torture test the motor driver. Unfortunately I was not able to run the driver past 1.5A RMS, which is a shame. I’ll try using a different motor with higher coli resistance. Anyhow here is an image from my thermal camera of the top of the ship:
The chip has no heat-sink and runs at 54C. This is not bad at all. much cooler than the TMC2130 version. The board seems to be dissipating quite a bit of the energy.
Here is a picture of the bottom of the board:
The bottom is at 45C in the center, which I think is quite good thermal conductivity of the board layers.
I feel good about the board thermal capabilities. If I add heat-sinks on the top and the bottom it should be able to run at 2A RMS and above with active cooling.
I dusted off my trusty pick and place and made one of the newly received TMC2660 driver boards.
Since it’s the first time I test this setup I populated only one of the driver chips – the X axis.
Alas it was all in vain. After fighting with it for several days, the motor would not spin properly. Either my stepper driver configuration so completely busted (although I double and triple checked) or the driver chip is fried. One of the phases works, but the other sends no current to the stepper motor.
Also I was trying to fit some automotive fuses on the board – you know for protection. Alas the fuse holders I ordered are very flimsy and don’t fit the fuses at all. Ordered a different set, but have to wait.
I spent a lot of time getting the PrntrBoard tmc2130 version to work. I’m at the point where I’m quite happy with it and don’t see major further changes. The tmc2660 branch did not get a lot of attention in the mean time.
So I spent a weekend completely re-designing the tmc2660 board. I ported all changes from the tmc2130 version. There is now a dedicated ground plane layer and routing it much easier.
I opted to put all drivers on one side of the board. Unfortunately limiting the size to 10x10cm (or 3.9×3.9 inches), I could not fit all drivers in one row. Hopefully cooling would not be major PITA as it was on the tmc2130 version.
Here is a screenshot of the 3D rendering of the redesigned board:
Please excuse my mistake, the top row of power connectors is facing backwards. Fortunately these are symmetrical and I can simply solder them the other way.
Here is a view from the top:
I used very aggressive layout for the connectors and I ended with some spare space in the middle of the board. I was thinking to add two automotive type fuse holders for extra protection. I haven’t quite settled on what fuse holder to use. Here are two renderings with the footprints in KiCAD:
And view from the top:
All changes have been pushed to my GitHub design repository page. The version with the fuses is in the tmc2660-fuse branch.