Thaks for the hint. I didn’t realize the category. Grbl-LPC is indeed not usable for 3d printing, but the board would also be interesting for laser modders, if pinout was clean.
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Just as an FYI, the Prusa Buddy board has integrated TMC drivers, although if bought from Prusa the stock bootloader only loads firmware signed by Prusa. There are versions from third parties that don’t have this limitation and are also cheaper.
I’m planning a Prusa Mini clone build, but I’ll probably use SKR Mini.
Thanks! I think they let you cut a warranty-voiding line to load your own firmware? Do you happen to know which TMC chips they are using? (I should start listing original and clones as separate lines in the table since clones aren’t necessarily quite the same thing.)
Yes, there is a breakable tab to enable unsigned firmware. The drivers are TMC2209.
I’ve not had any issues with the board (I have Prusa Mini), the LCD display is quite nice as it can display a preview of the GCode file for you when you forget what the heck flooble_PLA_0.2mm.gcode on that USB stick actually is (which is most of the time for me 
).
Not sure it is worth the cost for a budget printer though. I might try one of the clone Buddy boards, I am waiting for feedback from people who have bought the Mini clone kits.
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This evening, I got the dreaded TMC CONNECTION ERROR and one of my A/B motors isn’t turning, so one of the 2209s on my BIGTREETECH SKR Mini E3 V1.2 died. BIGTREETECH Direct SKR Mini E3 V2.0 (which has some added features, I think including protection against thermistor short circuits) is $45, but right now BTT on Amazon have a 5% off and free “BIGTREETECH DIRECT TFT35 V2.0 Smart Controller WiFi Display” and I can get it Monday and get the printer working again over the holiday break. So I’m not committed to staying on the BTT boards but as things go it is a cheap enough fix.
I also noted that there is a FYSETC board with 4 TMC2209s for $29 and added it to the matrix, but there wasn’t a lot of information on the Amazon page.
In the long run, I think I want to upgrade to something different but can’t decide what yet. Too many other things to think about.
Edit: Received the V2.0 today. Among other changes, it no longer exports STEP/DIR/EN signals for external steppers, making it harder to repurpose. It also doesn’t have a jumper to select “SPREAD” mode. I’m hoping that doesn’t matter. Thermal management looks better than the V1.2.
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The spread cycle versus hybrid is now set with uart not with the jumper. The thermals on the version 2 is a lot better. I’ve been liking BTT recently because they actually put a reasonable amount of information out on their github. Unlike most Chinese manufacturers. And they update the display regularly, I run a skin on mine to make it so it isn’t so ugly, but it’s a really usable interface.
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Ah. In my clone of git@github.com:bigtreetech/BIGTREETECH-SKR-mini-E3.git I did git pull and then diff -uNr firmware/V1.2/Marlin-2.0.7.2-SKR-mini-E3-V1.2 firmware/V2.0/Marlin-2.0.7.2-SKR-mini-E3-V2.0 and that brought enlightenment. 
I expect to be flashing this shortly.
I note that they are still showing the heat sinks on the chips instead of on the back of the board as I’ve recently learned probably makes more sense.
Maybe I’ll rebuild firmware for the old V1.2 with the dead TMC chip without TMC support and use it to drive monocle 
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I didn’t know that the 2209s run cooler than the 2208s, but that’s at least what this article says:
In particular, this:
The flexible and stealthy TMC2130 has 400 (bottom) and 500mΩ (top) (100mA 25°C supply=24V) mosfets, and runs hot – needing a larger heatsink to keep it working.
TMC2208 is a later generation, with 280mΩ (100mA 25°C supply=24V) mosfets, – although some folk say they still run hotter than A4988, but there is a lot of hearsay in the 3D print world, and I haven’t tried them, so maybe they are similar, or maybe StealthChop requires the mosfets to operate partially in linear mode, or maybe when people use them at 12V the transistors do not achieve 280mΩ.
Anyway, just introduced, the TMC2209 has 170mΩ (200mA 25°C supply=24V) mosfets – which must cut dissipation to some extent, and might even mean heatsinks can be done away if they are directly on a large pcb with plenty of copper – thick layers and lots of layers.
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Just added the Duet 3 Mini 5+, which has 5 TMC2209s. Looks like it’s not in stock yet so I haven’t found US pricing.
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Added two more BTT boards, one of which is 120Mhz and 5x TMC2209.
Might want to throw in the TH3D EZBoard that my buddy Griffin designed. It’s out of stock for now, but it does meet the criteria of the topic :).
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Oh I had meant to make this a wiki… Got a best link I should use? Happy to add it, I’d love this to be comprehensive!
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So TH3D says that they release GPL source to customers, which I guess implies that they only release it to customers. Does this mean that they have forked Marlin? I see that upstream Marlin has BOARD_TH3D_EZBOARD but I don’t know how that relates to what they provide to customers. If upstream Marlin doesn’t build “right” for some reason on the TH3D, we should probably make it clear in the table that it’s a fork. I’m confused here and would like to make sure the table isn’t confused. 
Also do you know what the CPU frequency is?
I don’t know about that - they have their own firmware build site, I’ve been able to freely download their Unified Firmware, and I was under the impression that stock Marlin has a board entry for the TH3D EZboard.
The LPC1769 is 120mhz but I do not know if the firmware runs it at 100 or 120mhz. Since the chip is capable of 120mhz, I would grant them that - they are paying more for the proper one, after all (the LPC1769 over the 1768 that many Aliexpress boards use to save cost).
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Yeah, stock Marlin definitely has it defined. Was just curious whether it was correct. Sounds like it is.
I tried to update with CPU and CPU frequency called out separately for each board. Not sure that anyone is going to buy a Prusa Buddy for a non-prusa printer and then break the tab to put their own firmware on it, so that probably doesn’t matter too much.
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Are you sure the Bigtreetech SKR mini E3 v1.2 has the LPC1768 and not STM32?
This one shows STM32…
https://www.aliexpress.com/item/4000378818588.html
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Oops. I even quoted from Marlin… STM32F103RC
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I’d only checked because it’s a nice size and price for my K40 experiments with LinuxCNC/Remora.
Currently using MKS Sbase v1.3 which does not have TMC drivers though.
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