gbulmer
Moderator
I was looking at the Maple rev3 Eagle CAD.
Just for giggles, I hit the Design Rules Check. Pretty nice.
Looking at the design rules, the clearances are 6mil. I tried 8mil (still under 0.25mm), and got lots of clearance errors on the pads for the STM32F. Did Okie 'oversize' the pads (which is what it looks like), or am I misunderstanding how Eagles Design Rules Check works?
This is low priority, just me being curious.
josheeg
Member
I am working on a open source maple done in kicad it is a free and open source program with design rule check and electrical rule check & autorouter etc.
Its video tutorials are good enough to get started but the manual that downlads with it is great also. You might have to click on the manual in synaptic package manager if you use linux. I would sugjest linux.
Free and open source hardware should be made with free and open source software and the learning curve is less than eagle I made 2 boards in eagle and 2 in kicad I won't ever go back to eagle.
the schematic symbol generator webpage is nice and the java footprint module maker helps also. Freeroute is the autorouter.
gbulmer
Moderator
josheeg - I agree with the "Free and open source hardware should be made with free and open source software" philosophy.
Otherwise we're just 'changing the master', and still fail to get freedom. Having said that I use Mac OS X, not Linux.
It is only recently that I've seen such positive reports about KiCAD. In fact, for me, LeafLabs decision to move is the clincher.
Previously a friend tried it (a while ago), driven by the open hardware on open software philosophy, and reported finding it better than Eagle, but still unpleasant compared to the proprietary tools which he was accustomed to. This coloured my view.
I am working on some boards, and my collaborator was okay with Eagle, but didn't want to go to KiCAD under our time pressure. But I hope to look at KiCAD before Christmas.
gbulmer,
Here's the calculation I get from the numbers on the datasheet for the recommended layout to get the spacing between the pads:
((7.8mm)-(16*0.3mm))/15 = 0.2mm = 0.00787401575in
The STM32 pad layout on Maple is identical to the datasheet's recommendations, which makes the space between the pads a little less than 8mils. I don't see how to derive what the width of the pins are from the package information, but they are probably narrower than the recommended pads, which means they probably are over-sized, if that's what you mean by that.
gbulmer
Moderator
Okie - thank you very much for answering. I realise you're very busy, so I appreciate you spending time on such a low-priority question.
I apologise, I should have updated my question.
I dug through 13587.pdf (STM32F103x8, STM32F103xB).
Your calculation exactly tallies with Figure 49 "Recommended Footprint" (for LQFP64), which shows pads are on 0.5mm pitch, but are 0.3mm wide, i.e. 0.5mm - 0.3mm = 0.2mm clearance.
Could anyone tell me if there is a way to look at the details of a package in an Eagle PCB .brd file (without the library)? That might have given me the answer without having to ask.
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