[NTLK] Designing an Internal WiFi Board for MP2x00

[Jake Bordens]

The hardest component to solder is the voltage regulator.  See page 3 of the data sheet. (http://www.ti.com/lit/ds/symlink/lmz21700.pdf) for a picture of the component.

It looks just like a passive component on the completed board, but its really full regulator with am inductor on top.  I'm not sure how easy it would be to do by hand.  You really want the large ground pads to be soldered to the board for heat transfer.

I took the opportunity to learn about doing reflow myself, and it turns out its not too difficult.  Use a stencil to apply the solder paste, place the components, and bake in a modified toaster oven.  There are plenty of YouTube videos on it.

That being said, I'm always surprised when it actually works.  Given the small pads on the underside of the voltage regulator, I always expect it to fail, but I've assembled 2 full boards and 1 partial board and each time the regulator worked.

Also, I did get some solder bridges on the connector pins and the line driver IC after the reflow cycle in the toaster oven.  Those were easily fixed by hand with a soldering iron, some flux, and some copper braid.



On 5/10/15, 4:28 AM, "Matthias Melcher" <mm at matthiasm.com> wrote:

>
>> On May 8, 2015, at 2:28 AM, Jake Bordens <jake at allaboutjake.com> wrote:
>> 
>> I'm about done with my internal WiFi project.  Just a few more odds-and-ends to tie up, but the latest revision of the hardware and newton-side software works great (and with hardware flow control too).
>> 
>> More info here: http://retronewton.blogspot.com/2015/05/wifi-board-v11.html
>
>Very very cool! I love it. I can do crude SMD soldering and I would be willing to solder three boards if there is no time pressure. I'd love to keep one for myself.
>
>As for the software side of things, another possibility is a proxy web server that converts web pages "on the fly" from modern code into plain old HTML that the MessagePad can understand.
>
>Matthias
>
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