LeafLabs Garden » Topic: I want RET6 Mini or, better yet an F4 Mini.

LeafLabs Garden » Topic: I want RET6 Mini or, better yet an F4 Mini. http://forums.leaflabs.com/topic.php?id=1390 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:14:11 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://forums.leaflabs.com/search.php gbulmer on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=3#post-8493 Sun, 04 Mar 2012 12:13:08 +0000 gbulmer 8493@http://forums.leaflabs.com/ MediumKahuna - <blockquote>Even so, it will be hard to get a BGA on a DIY board. </blockquote> Yes, it is hard to make good plated-through vias using DIY techniques (can be done, but expensive), and without vias it will be very difficult to route the 176 BGA. Unless there is a great insight, I wouldn't try. I'd use a commercial PCB. <blockquote>If you make all the balls sit on plated through holes (or at least the ones you need to connect to) shouldn't you be able to reflow a ball from the back side? </blockquote> AFAIK, industrial PBCs use 'microvia' technology to put a via through a BGA pad. I believe microvia diameter is 0.006" or less, and it is drilled with a laser. I don't believe they use normal drilled vias within BGA pads. The articles I've read use high-quality PCB tolerances to route the outer rows of the grid on one layer, then inner rows with blind or buried vias on multi-layer boards. AFAIK, they aren't reflowed from the back side, but the top as normal. If, as you suggest, some pins are unused, then it might be practical to get power into the middle of the 176 BGA on only a double sided board. If it's doable (for testing purposes) on a double sided board with fine tolerances, then a 4-layer board could have pure power and ground planes, and no buried, blind or micro vias, which would keep costs down, and make it easier to test. I found these references: <a href="http://pcdandf.com/cms/magazine/95/3760" rel="nofollow">http://pcdandf.com/cms/magazine/95/3760</a> <a href="http://www.fairchildsemi.com/an/AN/AN-5026.pdf" rel="nofollow">http://www.fairchildsemi.com/an/AN/AN-5026.pdf</a> <a href="http://www.altera.com/literature/an/an114.pdf" rel="nofollow">http://www.altera.com/literature/an/an114.pdf</a> <a href="http://www.ti.com/lit/an/sprabb3/sprabb3.pdf" rel="nofollow">http://www.ti.com/lit/an/sprabb3/sprabb3.pdf</a> MediumKahuna on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=3#post-8487 Sat, 03 Mar 2012 16:22:18 +0000 MediumKahuna 8487@http://forums.leaflabs.com/ A BGA on a mini has one thing going for it: you only need to connect to 1/3 of the pins on the MCU. This solves the problem of getting the signals away from the BGA. Also, with with so many pins to choose from, you can make the ones you do use, less contentious. Even so, it will be hard to get a BGA on a DIY board. I know you guys are into making DIY boards and I will be too, on my next board but, I have a coupon (if you will) to get some boards made cheap. I get two trys (2 batches of boards). I going to use it to make a Mini with a full boat STM32F4, 100BaseTX, and any thing else I can cram on there. I think I can do it by putting a BGA on a 4 layer board with plated through holes. If you make all the balls sit on plated through holes (or at least the ones you need to connect to) shouldn't you be able to reflow a ball from the back side? I'm back to trying to fit some RAM on there too. siy on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=2#post-8482 Sat, 03 Mar 2012 09:38:33 +0000 siy 8482@http://forums.leaflabs.com/ The only intent of posting this video is to show that working BGA without special equipment is quite complicated and not very well suited for DIY-ers. At least for most of them. Of course, times are changing and while few years ago most DIY designs were based on TH components, today most of them using SMD components. Same may happen with BGA. P.S. The main obstacle for me in regard to BGA is need to have plated through holes. Most BGA's interesting for me can't be brought out in single layer even with 0.1mm spaces/traces (and so far 0.1mm is still above my process capabilities, although I'm very close to these limits). P.P.S. If you need any help with solder mask - don't hesitate to contact me, I'm ready to share any knowledge/experience I have obtained while working with them. gbulmer on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=2#post-8479 Sat, 03 Mar 2012 08:41:57 +0000 gbulmer 8479@http://forums.leaflabs.com/ siy - Thanks for the video. Was it intended to persuade me that I'll never be able to do BGA ?-) I should admit, the fact that a 176pin BGA is *smaller* than a 64pin LQFP is exciting. If Chris has perfected making DIY solder masks, then it might be feasible to DIY BGA, but fixing a board is still beyond my skills. I'll show Chris the video, and see what he thinks. He is more skilled, and with a much, much better touch than me. siy on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=2#post-8475 Sat, 03 Mar 2012 05:23:08 +0000 siy 8475@http://forums.leaflabs.com/ @gbulmer: quite impressive video <a href="http://www.youtube.com/watch?v=JB1InDsWCjQ" rel="nofollow">http://www.youtube.com/watch?v=JB1InDsWCjQ</a> siy on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=2#post-8474 Sat, 03 Mar 2012 05:18:51 +0000 siy 8474@http://forums.leaflabs.com/ @gbulmer, I've never used BGA in my boards (although I'm going to try), but I think it is doable as long as PCB has solder mask. From the other hand, my experience with MLF packages (they are closest to BGA among ones which I ever used) suggests that there might be problems even for PCB's with solder masks. While smaller packages (<32 pins) are quite simple to solder, larger packages often caused problems for me. And while MLF can be easily desoldered and soldered again with hot air gun, BGA will require reballing after desoldering which is quite complicated procedure (although still doable at home). I guess that coffee is absolute taboo before doing it :) siy on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=2#post-8473 Sat, 03 Mar 2012 05:09:53 +0000 siy 8473@http://forums.leaflabs.com/ @okie, few early prototypes of Mini64 were using microUSB socket, but they I decided to return to miniUSB for very simple reason: everyday use of microUSB did show that it's very easy to break it from PCB. This never did happen for me with miniUSB despite much heavier and much less careful use. gbulmer on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=2#post-8463 Fri, 02 Mar 2012 22:20:02 +0000 gbulmer 8463@http://forums.leaflabs.com/ MediumKahuna <blockquote>3) BGA. I've got some links here that say its possible to hand assemble a BGA. This solves any MCU pin count problems as the 176 pin BGA is smaller than a 64 pin sop. I haven't really looked at these links so I'm not sure I believe it yet. <a href="http://openhardware.net/Misc_Stuff/ToasterSMD/" rel="nofollow">http://openhardware.net/Misc_Stuff/ToasterSMD/</a> <a href="http://articulationllc.home.comcast.net/~articulationllc/sm0402.htm" rel="nofollow">http://articulationllc.home.comcast.net/~articulationllc/sm0402.htm</a> <a href="http://www.seattlerobotics.org/encoder/200006/oven_art.htm" rel="nofollow">http://www.seattlerobotics.org/encoder/200006/oven_art.htm</a> <a href="http://www.ustr.net/smt/oven.htm" rel="nofollow">http://www.ustr.net/smt/oven.htm</a></blockquote> I looked at those four links, and the browser Search didn't find 'BGA' in any of them. Did you not post one? gbulmer on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=2#post-8462 Fri, 02 Mar 2012 22:06:14 +0000 gbulmer 8462@http://forums.leaflabs.com/ MediumKahuna - <blockquote>STM32F417IGH6 in a 176 pin BGA, $12.00 DP83848I Ethernet PHY 8.00 TG110-S050N2RL Isolation Module 2.00</blockquote> Even if I felt okay making a board using BGA, I have less idea how to find and fix a bad BGA connection if its under the chip, but Go for it. MediumKahuna on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=2#post-8461 Fri, 02 Mar 2012 21:52:00 +0000 MediumKahuna 8461@http://forums.leaflabs.com/ STM32F417IGH6 in a 176 pin BGA, $12.00 DP83848I Ethernet PHY 8.00 TG110-S050N2RL Isolation Module 2.00 Miniture connector (still learning) They all fit on a 2" by .8" or even Maple Mini compartible board Better go, power has been out a while and I'm torturing my lead acids. gbulmer on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=2#post-8460 Fri, 02 Mar 2012 21:36:39 +0000 gbulmer 8460@http://forums.leaflabs.com/ MediumKahuna 1) Certainly 0805 and probably 0603 In my experience it is easier to start with a 0805 design, substitute 0603, and compress it than vice versa. I'll stick with 0805 or bigger to make it easy to hand assemble. 2) All SMD (which is probably all of the parts) on one side (maybe we could stretch this a little and put a chip or two on the other side). As soon as you put SMD parts on both sides, the simple 'toaster oven' or 'electric skillet' techniques become harder, which is what I want to avoid. My technique is to put through hole parts on 'the other side' to the SMD. This can free up space, and seems to work okay for switches, plugs & sockets, LEDs etc. Components on both sides will always be a bit more challenging. 3) BGA. I am willing to believe folks can do it, but IMHO it is hard to debug and fix. So it isn't a good fit for SMD newbies. I'd love a home brew pick & place machine. If there were a viable machine, *starting* at sub $1000 (but maybe going up to quite a realistic price) I think quite a lot of colleges might get one to try. Four Layer I have no fundamental problem with using them for 'production', but I like to prototype with two sided because we can DIY them. I quite like using Eagle (I never thought I'd ever say that). I either need to buy Eagle, get comfortable with DesignSparks, KiCAD or some other Open Source ECAD package before I'll do 4-layer. I also think that by abandoning Arduino header compatibility, signal interaction, and hence analogue noise, is reduced. Further (I think) by changing a few signals, which will require new board files for the IDE, and new #defines for bootloaders, signal interaction can be reduced even more. So analogue noise might be better than folks expect. Think of it this way. By using a single layer signal layout (no signals crossing at all), and a carefully designed ground plane, you might get acceptable noise figures. Then by using a simple adapter to get to Arduino-header compatibility, you get the other two copper planes, but in a cheap, optional way :-) Seven, Pin functions Using my 56-pin layout, all signals for a 64pin part, except USB and main crystal oscillator, are available on a giant-DIL 1.2" pitch format using PCB design rules that we can DIY. I have done a quick (experimental) routing using commercial tolerances on 0.9" pitch. That gives 50 signal pins, 5V (USB), digital 3.3V & ground, analogue 3.3V & ground, and Vin. Rod and siy have shown that it can be shrunk even further. So, if you want 2x28 pins, I am confident you could have a 64pin STM32F4 on 2.8" x 1.0" PCB. Using Rod and siy's approaches, even smaller. We all have on-board power regulators. Siy has a beefy digital supply. I can't remember Rod's design. Inspired by siy, I might change my power regulator approach. Have a look at the data sheet, and see if that is enough for your non-Ethernet, non-external memory needs. Roughly, some pin-constrained combination of: 16 ADC channels, with any channel to any of the three ADC's 2 DAC 15 or more PWM (IIRC it was 15 PWM on STM32F103 medium density) 3 SPI 3 I2C 4 USART 2 CAN USB HS JTAG/SWD any pin can be digital I/O For me, the Arduino-headers are a second adapter board. That is almost the other two layers of a 4 layer board. Schools in the UK don't use LiPo's because they are quite delicate and dangerous (rarely explode, but do burn well, I'm told). Micromouse and small robot makers don't seem to put LiPo chargers on board because the robot is either not connected to anything that could charge the batteries, or they use several sets of batteries to keep the robot continuously active, so they have 'proper' LiPo battery chargers. Also, many use 7.2V or even 11.1V LiPo setups, making it quite complex. So I am not trying to get LiPo charging on anything. gbulmer on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=2#post-8458 Fri, 02 Mar 2012 20:41:44 +0000 gbulmer 8458@http://forums.leaflabs.com/ siy - <blockquote>... large 1.5-2X desktop lens with shadowless backlight makes soldering of 0603 extremely convenient. ...</blockquote> It isn't just my eyesight, it is the steadiness of my hand!-) No strong coffee in the morning for me :-( Unfortunately, schools in my local area don't seem to have a classroom-full of good desktop lenses. I know we don't have enough at the hackspace. Worse, teenage children can be a bit clumsy and uncoordinated, and older folks are less steady than they once were. So some will be able to do 0603, but their seems no purpose in designing boards which are too challenging. My current view is I'd rather make them bigger, and use easier to handle components, so that more folks can succeed. gbulmer on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=2#post-8457 Fri, 02 Mar 2012 20:31:37 +0000 gbulmer 8457@http://forums.leaflabs.com/ okie - I think we are exploring a different 'volume' of the requirements and design space from LeafLabs. siy and I are interested in making it easy and cheap to prototype using DIY boards. We've abandoned Arduino-compatibility, so we can reduce signal interaction compared to Maple trying to mimic Arduino headers. siy has been able to route a single sided PCB. So following his approach, a two sided board could have a carefully designed ground plane, which might have the potential to reach good noise levels. siy can get several 'turns'/day using DIY PCBs. Trying many prototypes may get there. A PCB designer, trained on high-end ECAD, has suggested to me that if I had access to state-of-the-art ECAD, it is likely good noise levels can be reached because that is what modern, high-end ECAD can help with. I've also spoken to a guy who 'quietens' boards. He believes he can identify small changes to a board to reduce noise because that is what he does for a living at an electronics company. I am no expert, but based on those conversation, I'm hopeful there may be several ways to get good results. One of my interest is developing boards that inexperienced folks can build. Ideally, I would like to enable them to make a DIY PCB, then assemble the board. I'm also aiming for a layout I can embed into larger designs, so I constrain my routing options more than siy. Hence I am willing to compromise on noise to reach that part of my solution space. Edit: <blockquote>Also, do you all get the sense that it's time to switch to microUSB from miniUSB? </blockquote> Some folks have USB mini cables, and they are cheap and easy to get. Mini feel more robust a connection than micro, but that might be purely tactile and not real mechanically. I have not found any through-hole USB micro sockets, but I have found through-hole USB mini sockets. If you remember, several people pulled the USB socket off a Maple, so a through-hole socket seems to be a handy fall-back. I've had real problems finding a USB Micro OTG plug to USB A *socket* cable (plug USB Micro OTG plug into STM32F4-Discovery socket, and plug a USB flash stick into the A socket) MediumKahuna on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=2#post-8450 Fri, 02 Mar 2012 12:58:39 +0000 MediumKahuna 8450@http://forums.leaflabs.com/ Ethernet Digging. I popped up some options for on board Ethernet (100Mb): BGA MCU with MAC, 44 pin PHY, little transformer, mini connector. For 64 pin MCU chips we need a PHY and a MAC Chips with both come with SPI, SDIO, and High Speed USB (MCU host) interfaces suitable for STM32F415RG ish MCU. The STM32F415RG SPI only runs at 37.5 MHz so we'd only get 1/3 throughput. The SDIO looks promising but, I haven't found actual chips (need the chip set from a Cardbus NIC. USB NICs can go on or off the board but tie up our only High speed USB port. maybe we could make the OTG port look like a USB hub and so still have a least a high speed USB host along with the NIC. There might be an option for a brain damaged MAC that only does 100BaseTX full duplex (so it wouldn't talk to a Ethernet hub, only switches and other devices). This would be in the form of another micro on board). MediumKahuna on "I want RET6 Mini or, better yet an F4 Mini." http://forums.leaflabs.com/topic.php?id=1390&page=2#post-8449 Fri, 02 Mar 2012 12:32:31 +0000 MediumKahuna 8449@http://forums.leaflabs.com/ Requirements (Continued) Six, Hand board assembly (soldering to, way, old school types) I can't see anyway around a requirement for hand assembly. Thanks to gbulmer, siy we are homering in on what that means in terms of board design: 1) Certainly 0805 and probably 0603 2) All SMD (which is probably all of the parts) on one side (maybe we could stretch this a little and put a chip or two on the other side). 3) BGA. I've got some links here that say its possible to hand assemble a BGA. This solves any MCU pin count problems as the 176 pin BGA is smaller than a 64 pin sop. I haven't really looked at these links so I'm not sure I believe it yet. <a href="http://openhardware.net/Misc_Stuff/ToasterSMD/" rel="nofollow">http://openhardware.net/Misc_Stuff/ToasterSMD/</a> <a href="http://articulationllc.home.comcast.net/~articulationllc/sm0402.htm" rel="nofollow">http://articulationllc.home.comcast.net/~articulationllc/sm0402.htm</a> <a href="http://www.seattlerobotics.org/encoder/200006/oven_art.htm" rel="nofollow">http://www.seattlerobotics.org/encoder/200006/oven_art.htm</a> <a href="http://www.ustr.net/smt/oven.htm" rel="nofollow">http://www.ustr.net/smt/oven.htm</a> Maybe the next project should be a home brew pick and place and solder paste machine. Actually I have or could recreate all the code from a real, commercial, pick and place machine (including machine vision) which I developed for Universal in the early 90s. Universal is now defunct. Four layer board I've got a bunch of Nays and only 2 (counting me) Yays for a four layer board. I think of a four layer board as a two layer board with ground and power plans in the inner layers. We don't need to make the number of layers a requirement (we can drive off that bridge when we get to it) but its starting to look (to me) like we won't have a choice anyway (will have to go 4 layer to make layout work). Besides I have these great connections for getting the boards done. Seven, Pin functions Personally I just need all the analog I can get and a decent shot GPIO (besides on-board high speed interfaces). But, maybe there are some functions that the world just can't live without like serial, full speed USB, CAN, etc. Also the Lipo connector on the Maple is a nice touch to keep in mind. So, for starters (not in any order): 1) At least two channels for each of the ADCs 2) The DACs 3) decent shot of GPIO, PWM 4) A respectable Arduino interface. 5) digital, analog power and ground I'm assuming typical, on board power management (a couple of LDOs) Eight, I forgot what eight was for. Nine, 'cause I lost count. Ten, is for everything, everything...