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I used [[http://fritzing.org/|Fritzing]] to lay out a two-layer !SpiffChorder development board and submitted an order for the prototype to [[http://fab.fritzing.org/|Fritzing Fab]]. The fabrication cost for one unit, including international shipping to the USA, was roughly US$40. I'll post pictures once it arrives in a couple weeks and I have a chance to run tests, but here are some preliminary details: I used [[http://fritzing.org/|Fritzing]] to lay out a two-layer !SpiffChorder development board and ordered a prototype copy of it from [[http://fab.fritzing.org/|Fritzing Fab]]. The fabrication cost for one board (including international shipping to the USA) was roughly US$40, and I had it in my hands within a couple weeks. I soldered in all the components, wired it into my test keyer and everything checked out. I'm going to order a handful updated with the silkscreening depicted in the [[#Paper Placement Test|paper test]] below, and post updated pictures once those arrive. In the meantime, here are some preliminary details:
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= Condensed Board =
For implementation in tighter spaces, I plan to design a stripped-down board omitting CON1, removing lines for M1-3 and UC from CON3 and the associated R15-18, using an 8-pin array (Digikey part MSP10KH-ND) for R8-14, reordering the remaining lines on CON3 to support more direct paths through the PCB, and replacing the GND line from CON4 with VCC like I did on the perfboard layout (since CON3 exposes GND anyway). I may also go with lower-profile parts for C4 and X1 so that skipping the socket for IC1 and the screw terminals for CON2-4 allow the assembly to be about half as thick.

= ATmega32u4 =
Once I get more familiarity with AVR development, I'd like to roll up my sleeves and try my hand at implementing a !SpiffChorder clone on Adafruit's [[http://www.adafruit.com/products/296|Atmega32u4 Breakout Board]].

Printed Circuit Board Layout

I used Fritzing to lay out a two-layer SpiffChorder development board and ordered a prototype copy of it from Fritzing Fab. The fabrication cost for one board (including international shipping to the USA) was roughly US$40, and I had it in my hands within a couple weeks. I soldered in all the components, wired it into my test keyer and everything checked out. I'm going to order a handful updated with the silkscreening depicted in the paper test below, and post updated pictures once those arrive. In the meantime, here are some preliminary details:

Bill of Materials

So far I'm using the same BoM from the perfboard design, but I'll probably switch up CON1 with Digikey part 609-2845-ND (vertical rather than right-angle) so as not to block the lower-left mounting hole.

Paper Placement Test

Here's a paper test using a 1:1 scale printout of the silkscreen and solder mask together:

SpiffChorder paper test

Connector Detail

The 0.1" pitch right-angle screw terminal blocks I used are just slightly longer than 0.4" each. So as to be able to fit the four for CON3-4 directly adjacent to one another, I lightly sanded the facing sides until they fit snugly but evenly in a piece of perfboard. In an effort to make it easier to solder these evenly on the board, I attached their sides together with a tiny dab of quick-setting adhesive gel (being careful not to get it into the terminals themselves):

screw terminal sanding screw terminals glued

Condensed Board

For implementation in tighter spaces, I plan to design a stripped-down board omitting CON1, removing lines for M1-3 and UC from CON3 and the associated R15-18, using an 8-pin array (Digikey part MSP10KH-ND) for R8-14, reordering the remaining lines on CON3 to support more direct paths through the PCB, and replacing the GND line from CON4 with VCC like I did on the perfboard layout (since CON3 exposes GND anyway). I may also go with lower-profile parts for C4 and X1 so that skipping the socket for IC1 and the screw terminals for CON2-4 allow the assembly to be about half as thick.

ATmega32u4

Once I get more familiarity with AVR development, I'd like to roll up my sleeves and try my hand at implementing a SpiffChorder clone on Adafruit's Atmega32u4 Breakout Board.


back to The Man-Machine...

CCL: ManMachine/KeyerPCB (last edited 2012-07-02 21:40:29 by fungi)

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