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RandomElectrons RELP-2 LaunchPad

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I was wondering about that myself. No placement is set in stone at the moment.


The only thing that might change the placement of components is a future RF booster board. 


Right now, I am fearful that the placement of the DC jack will degrade the performance of a WiFi, ZigBee or Bluetooth booster board. 


This board shape is only 100 mm x 62 mm so it really isn't that big.  I have created all of the Sick of Beige board shapes so I could use any of them if the need arises.


I think I am wanting to create order out of the chaos of board shapes.



I am open to suggestions. Is there any alteration(s) that you think would work better?

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It doesn't seem to matter yet.


I think that is why I am hammering out several designs all at once. I want to see what placement patterns develop and then optimize all the designs for consistency.


Ideally, I would like to have the USB, Reset button and the DC jack all on the same side. 


I suppose I could move all the LEDs to a different board edge.

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I am thinking of making some of my next designs in the sick of beige templates. (Thanks for making them for altium btw)


Are you sticking with mini-B over micro-B for any particular reason? I was just reading that the templates have mini-B mounting holes. So I guess it's a standard for the template.


I just thought that micro-B is much more durable over time than mini-B


If you moved all the LEDs into a row along the top-right edge you'd have room for the DC jack on the right edge.

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I don't know which USB connector is stronger. My gut instinct is that smaller == more fragile so I imagine that the miniB is stronger.


I do like the idea of moving the LEDs to the upper edge. On the first design, they are TX/RX traffic indicators so it seemed right to put them by the USB connector. Maybe I will revise that design too.


I am also wondering, should I design in your eZ FET Lite circuitry just to be complete?

Or should I stick with the 4 pin Spy BiWire port?


Maybe that is what @@bluehash was saying when he asked about the debugging functionality?

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I don't know which USB connector is stronger. My gut instinct is that smaller == more fragile so I imagine that the miniB is stronger.


In theory it's supposed to be the other way around. The micro USB connectors were designed after mini USB, and fixed some flaws in the physical design.


Mini USB was originally designed for up to 1000 connect/disconnect cycles, which is not a lot. Micro USB was designed for up to 10000 cycles (still not a lot, but probably good enough for most uses). One of the changes was to move the parts that are likely to fail from the socket to the plug. That generally makes replacement easier.


That said, mini USB does feel nicer to use due to the extra bulk. I've never broken a micro USB, but the plugs do feel liable to snap off whenever you use them.

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A debugger probably adds more cost than necessary. Most of the time I find myself only using the debugger for programming.


I now have a suggestion :D

You should add another button wired up to enable the USB BSL.


and on the ones with a USB > serial, connect the RX/TX lines to the USART BSL pins + RTS/DTR to the RST/TST programming pins.

The newest mspdebug has support for entering the BSL using these pins.

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Oh yes! You are right. I do have to add that.


Is there a document describing the Serial BSL activation wiring?

Maybe it is on a schematic somewhere?




Concerning the debugger, I really wanted a simple design. Part of me wanted to let people assemble this board if they wanted to. That's why I am using 0805 components on it. If I add the debugger then I increase the assembly complexity and unit cost. Why? It looks like the debugger circuit uses 0402 sized parts on it. I do not want to put those on by hand so why would any one else want to?


Crazy Side note to self: Create a contest where entrants design circuits using the smallest components they dare. It must be assembled by hand and must do something useful i.e.: design and build the tiniest launchpad board ever and make it spell out 43oh.com on an off-board I2C display. What do you thing @@bluehash?



Back to the debugger... I like the four pin SBW for its simplicity. I may create my own version of the debugger board and see if I can integrate it into these designs using a high density SMT board to board connector set. Something like Hirose or Samtec. That way, a person could plug it on, debug until happy then unplug before deploying permanently. I have a picture in my mind. I will have to craft something up to see how it might work.

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Just because the parts are larger doesn't mean it's easy to hand assemble.

You are right about adding cost. The 5529 is the most expensive part, and you need 2 if you have a debugger.


But you shouldn't fear the 0402 parts. They can easily be switched out for 0805, this is a demo I whipped up.



I would definitely be in for that competition! I have some 0201 parts I need an excuse to get mad at while attempting to tack them down. >:)


An external debugger does seem like a better way to go, keep individual board costs down.

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From the BSL programming guide ([Tipdf]slau319[/Tipdf])






Also, mspdebug allows you to specify your own entry sequence. (http://sourceforge.net/p/mspdebug/code/ci/d2f8592124a436ae88ac664715990adbf3bb48b7/)

Specify a BSL entry sequence. Each character specifies a modem control
 line transition (R: RTS on, r: RTS off, D: DTR on, d: DTR off). A comma
 indicates a delay. The entry and exit sequences are separated by a
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I think I found some BGA MSPs while designing my relaunchpads.

Those would be fun to route, eh?


I like the 0805s because I can solder them without a scope. But let's face facts. Soldering down hundreds of SMT parts sucks no matter what size they are.


I did a job once where I had to had replace a 9 ball BGA dual op amp chip on several boards. It was this device: http://www.analog.com/en/all-operational-amplifiers-op-amps/operational-amplifiers-op-amps/ada4691-2/products/product.html


In the end, I replace 375 devices by hand using a hot air wand and a stereo microscope. Painful but gratifying because they all worked after I was done with them.


I'll do my design research on my debug board idea and let you know what I learn.


Your debugger looks great with 0805s.

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