Hi Seb,
On Sat, Feb 5, 2011 at 1:48 AM, Sebastien Lelong <[email protected] > wrote: > Hi Vasile, > > Thanks for your feedback too ! > > Are you saying it's possible to make such a board only 20% greater than > Xbee ? I could try to redesign it, but the bottleneck will pin header > connectors. > true, you've chosen a header which is a compromise between size and space. > Also, on my first tries, there were many many vias, and I tried to have as > few as possible. Going that small will mean more vias. Is this a problem ? > For instance, PIC's datasheet says caps near xtal should on the same side. I > tried to respect this. > of course but you can use as well a SMD crystal on the micro side or on the opposite side as well > > What about the fuse ? Do you think it's properly positioned ? Since there > are many power source options, I can't put a fuse for each... > well, I dislike your style of powering board (JP3 and JP7 both ON by mistake could kill your USB) but that is, usually the fuse is protected by the micro or by the regulator, however one smd fuse (thermal or breackable) is enough, but I'm affraid yours will not protect something... About jumpers, a good board has the smallest possible number of jumpers and variable resistors... even using 1-2 transistors instead of 3 jumpers is often better (mostly when the board is designed for beginners). > > Cheers, > Seb > > 2011/2/5 vasile surducan <[email protected]> > > >> >> On Fri, Feb 4, 2011 at 8:59 AM, Sebastien Lelong < >> [email protected]> wrote: >> >>> Hi guys, >>> >>> >>> So...I'm back, after several tries. >>> >>> It was possible to keep most features, specifically providing 2 voltages, >>> 5V and 3.3V. This was quite a mess though, mostly Xbee requires 3.3V, and >>> possibly voltage shifter on inputs (datasheet says it's not 5V tolerant, but >>> some report it is in reality). So I removed 5V regulation, and kept only >>> 3.3V, making this board more 3.3V devices friendly. If Xbee isn't wanted, >>> then one would just put an AMS1117-5V instead of 3.3V version. >>> >>> I worked again on power supply inputs. There can be 4 sources: USB (5V >>> regulated to 3.3V), external (5-9V regulated to 3.3V), serial (no regulation >>> so must output 3.3V, quite rare), and battery (direct, no regulation). I put >>> a fuse after the regulation part. >>> >>> Since I had some room left, I added a microSD slot, though I still wonder >>> how I'll solder it... :) It's on the bottom side. If replacing 3.3V >>> regulator with a 5V one, again SD-card won't work. >>> >>> I doubled shield/breadboard connectors to allow breadboard + shields at >>> the same time. User could also solder some wires to plug the board to >>> external daughter, using external connectors/holes. Shields can also be on >>> top or bottom, both, etc... >>> >>> I may also add another pin header which would include supplied voltage, >>> making it available to shields/breadboard (voltage coming from USB, >>> external, ...). >>> >>> Anyway here's the result, see attached files: schematic, PCB, PCB top, >>> PCB bottom (some comments are wrong, sorry). >>> >>> >>> Feedback appreciated. Highly ! >>> >> >> Your designs looks better and better. However there is HUGE empty space >> on your board. Look for example the footbal field between the crystal and >> the micro. >> When using SMD one of the reason is miniaturization. But your board is >> still huge. >> You cand do it with only 20% larger than the xbee itself? >> >> Vasile >> >> >> >>> >>> >>> Cheers, >>> Seb >>> >>> >>> 2011/1/30 vasile surducan <[email protected]> >>> >>>> >>>> >>>> On Sat, Jan 29, 2011 at 10:49 AM, funlw65(Vasi) <[email protected]>wrote: >>>> >>>>> I think you will need to design two boards. One supporting USB uCs and >>>>> second for serial uCs. Keep 1206 smd components, otherwise you must >>>>> provide the board assembled. And this is because of 5x5mm limit. >>>> >>>> >>>> >>>> >>>> >>>>> Try >>>>> to see how many features you can put on a single type of board. >>>>> >>>> >>>> all you need... >>>> >>>>> >>>>> Vasile >>>>> >>>>> >>>>> On Jan 29, 6:03 am, Sebastien Lelong <[email protected]> >>>>> wrote: >>>>> > Hi guys, >>>>> > >>>>> > Here's my last version, including a 500mA fuse (not resettable, but I >>>>> only >>>>> > have this one in my eagle lib), a rectifier diode for reverse >>>>> polarity >>>>> > protection, onboard LED moved to RC2 (CCP1 pin). Some remaining >>>>> "doubts": >>>>> > >>>>> > - which package would I need for the diode: DO-214AA, DO-214-AB or >>>>> > DO-214AC ? >>>>> > >>>>> > - I still have doubts about the power supply part. Initially, I >>>>> wanted to >>>>> > have power through USB or a battery. The board should handle 3.3V and >>>>> 5V, as >>>>> > an option. When using a battery, say 2 x 1.5V AAA cells, I'd need to >>>>> bypass >>>>> > all regulation (maybe even a pump like this: >>>>> http://www.sparkfun.com/products/9216). Using a rectifier diode will >>>>> also >>>>> > drop the voltage down and may not be compatible. But I could also use >>>>> a 9V >>>>> > battery, and thus need 5V and/or 3.3V regulators... and what if 3.3V >>>>> is >>>>> > bypassed, but not the 5V regulator ? Xbee board will be powered with >>>>> 5V, >>>>> > instead of 3.3V!!! You guessed it, I want many things and I'm not >>>>> sure which >>>>> > is most important at this phase. Any input, advices ? I think when >>>>> I'll >>>>> > start to create the PCB choices will be easier to make as I discard >>>>> options >>>>> > to gain room :) >>>>> > >>>>> > - I added pin headers, 2 x 14 pins, I may add another one dedicated >>>>> to >>>>> > power pins (like in Medium) if I get enough room (I doubt about it) >>>>> > >>>>> > In order to save some precious room, I'm thinking of (high priority >>>>> to low): >>>>> > >>>>> > - removing Reset-via-RTS option and make it always available (2-way >>>>> jumper >>>>> > saved) >>>>> > - remove two I²C jumpers, always make the board acting as a master, >>>>> and if >>>>> > not wanted, just don't solder the resistors >>>>> > - remove CTS jumper option (not used often ?) >>>>> > - remove power from serial module option, focusing on USB or >>>>> battery >>>>> > - keep only one regulator, adding an optional resistor to match >>>>> required >>>>> > 3.3V for Xbee when using 5V reg only. >>>>> > - move to 0603 smd components..... >>>>> > >>>>> > Any feedback highly appreciated! >>>>> > >>>>> > TIA >>>>> > Cheers, >>>>> > Seb >>>>> > >>>>> > 2011/1/25 mattschinkel <[email protected]> >>>>> > >>>>> > > > Maybe I should just use two different voltage regulator, one >>>>> AMS1117/5V >>>>> > > and >>>>> > > > AMS1117/3V3. Having only one component would have helped while >>>>> sourcing >>>>> > > > them. >>>>> > >>>>> > > On one prototype board I bought, there is only a AMS1117/3V3. They >>>>> > > assume you want to input > 5v and get 3v output. If you want >>>>> another >>>>> > > voltage you can put a jumper (just solder) to connect the >>>>> input/output >>>>> > > of the regulator so your voltage is whatever the input is. >>>>> > >>>>> > > Matt. >>>>> > >>>>> > > -- >>>>> > > You received this message because you are subscribed to the Google >>>>> Groups >>>>> > > "jallib" group. >>>>> > > To post to this group, send email to [email protected]. >>>>> > > To unsubscribe from this group, send email to >>>>> > > [email protected]<jallib%[email protected]> >>>>> <jallib%[email protected]<jallib%[email protected]> >>>>> > >>>>> > > . >>>>> > > For more options, visit this group at >>>>> > >http://groups.google.com/group/jallib?hl=en. >>>>> > >>>>> > >>>>> > >>>>> > jaluino_v03_bee_schematic.png >>>>> > 62KViewDownload >>>>> >>>>> -- > You received this message because you are subscribed to the Google Groups > "jallib" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<jallib%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/jallib?hl=en. > -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
