It works as it is, plese comment only if you have further improvements or want to discuss details
If you want to get the footprint for your design program I can mail it to you (Gerber or Diptrace libary)
3 orientation pins are sticking out further and rest in viases
6 Pins are connected on the driver design to the MCU pins for programming, any MCU that can be flashed with USBASP programmer
Glad I stumbled across this. I am working on a driver for the BLF Ultimate Lantern, and planned on adding reprogramming vias. I had no guidance on spacing or location, but it makes sense to make it compatible with this device. I know you are open to comments here, but any idea when this design will be complete? Also, I missed why the center to center spacing is not symmetrical for the hole on the far left. Is that part of the keying?
Also, for making it even more compact, what about having only 6 pins total and making some or all of them vias? For people who don’t have a key, vias are a lot easier to use than pads.
It’d be awesome to get a standardized BLF programming layout and key, so I hope to maximize the amount of drivers it can fit on while minimizing the barrier to entry.
making all programming pins viases blocks a bunch of area on small drivers likely make routing very hard if its packed with componets, with pads you are way more flexible, as they block that area only on one side
It is possible to remove one centering via where now 2 are, you can design the driver with just 2 centering viases
also tolerances play a big hole making it 6 viases, 6 pads are far more tolerant if pogo pins not aligned perfectly
0.91 is the solder Mask I cleared around the viases, fabs often fill the viases with solder mask if you have no clearance around them
also the fab has to produce from your gerbers there is no converting pitch 1.3mm to 50mil
also the 1.3mm was choosen so you can route a 6mil trace between the pads and pads and viases, if its 1.27mm you can not route it with the nessesary clerarance withoput making the pad and viases smaller
Agreed, no orientation pins required. This is not a tool for the un-initiated, placing it the right way is hardly rocket science.
The point of this is to facilitate ISP with the latest MCUs where external clips are not an option (no leads). Which was always a rickety arrangement, involving USBasps, headers, cables, clips etc.
Best if all pads are also vias, so self-locate.
Six pads/vias. No more. No extra “orientation” stuff, just obvious silk screen.
Frankly, this was all sorted out long ago, it’s not new, e.g. just google “pogo pin isp programming adapter” and follow the (unofficial) standard.
OK, I agree 0.1 inch spacing is quite large by modern standards.
But what is available at smaller pitch ? The smaller you go, the more esoteric the components become, and the method of assembling them. An FR-4 key is as basic as it comes, maybe a bunch of pins glued together with e.g. Sugru even worse. When I started this idea I suggested a 3D printed matrix to assemble things, I still think that’s the way to go for something reliable. But lets see where this goes.
Bottom line is that a standardised ISP connection on the accessible face of the driver is very desirable. If it can be connected with a click or a twist, even better. But a simple pressure contact with half a dozen pins on a standard pattern would be fine, even if only a couple are vias, for location.
this is why someone wrote me to use 2 traces so the pins self center themselfes while reflowing
with this method no worrying about it, just put solder paste and pins on the board and reflow it, perfectly aligned
on most of my smaller driver designs going with a 6 viases programming footprint wont work, because its literally packed by tons of traces on top, and also the spring pad and other stuff will limit it a lot where you can place the programming port
Problem with this is often below the MCU is something that blocks it like spring pad or so
here a driver example with 24mm size, not as small as a 17mm for example, I had no idea if its even possible to get the 6 viases on my 17mm or not
I thought about it why not make a 7 pin pattern which works for pads and viases, and modified it a bit
I have no experience with this so I can’t comment on the design, but being able to program the driver without having to remove anything is just awesome Lexel. :+1: :+1: :+1:
It might be possible to make the connector even smaller though, by moving that ground via into the old ground pad’s location. Or maybe it could be useful to re-add the ground pad, so the driver layout can use either the via or the pad (or both) depending on what fits easiest. Sometimes a really small board could end up using only one orientation pin, but that’s not necessarily a problem. Small boards would even have the option of omitting both guide vias if space or layout restraints are tight.
I found aligning it on 0.8mm pads with only one via would be hard, but yes generally you could say make at least 2 of the pads as viases so the key aligns to the other pads
I think some people are underestimating how small this thing is with only 1.3mm pitch
likely best would wotk get 2 of the outer connections as viases, which ones they are is less important, but I designed 2 pogo pins to be sticking out further on the key (- and 2. centering via)
the further their disteance is the less gets twisting an issue just notice if used only 6 connection pins the max distance is 2.6mm
also thinking about a key with a header for USBasp