LED Matrix Generator for EAGLE

Ted Yapo is designing a display for his  LED Oscilloscope Mk. II and decided to automate the process:

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16×32 Display Design

I painstakingly drew the schematic for 512 LEDs in this display, then endured the drudgery of laying out the board. The whole process took about 45 seconds. Yes, I wrote a few Eagle User Language Programs (ULPs) (elapsed time after the scripts were written and debugged). The previous time I wrote one was last century to lay out a circular LED clock face. I figured it was about time I regained those skills.

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The EAGLE ULPs are on GitHub:

led-matrix-generator

 Eagle scripts for LED matrix display generation

LED Matrix Generator for EAGLE

Protosnap

We’re huge fans of Sparkfun’s old school ProtoSnap kits. These include a small support tab with traces running between different sections of the board. They’re great for kit designs, allowing for both immediate out-of-box functionality, and eventual customization.

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Due to our shipping and panelization process, this type of board is not fully supported, but can be fabricated with careful consideration and experimentation.

Design Considerations

These designs are almost always unique, since the number of shapes, sizes, and orientation varies wildly. The design also may need adjusting based on the intended user.

in orientation, intended usage, and shape. As a result, a bit of experimentation is always going to be required. However, here’s a few design tips to get things going.

  • Always ensure that after snapping, you can connect the boards together easily. A small header pinout near the tab works most of the time, but some designs might work best with a special connector.
  • Tab width is critical. If the tab is too narrow, it will not hold the board together well. Too wide, and it becomes difficult to break apart. 3-5 trace/hole pairs works best.
  • Hole size / pitch. The best tabs have between 20-30 mil of material between the holes. A hole size of 25 mil generates pretty good tabs.
  • Design permitting, having multiple tabs with 2-3 holes is better than one huge tab with 6 or more connections.
  • Adding traces on both top and bottom of a tab is likely to result in difficult snapping. Consider instead using more tabs, or adding instructions to score the traces.
  • Tab and board placement: Remember that your users has to remove these! If the boards are badly positioned, the tabs aren’t “snapped” as much as they are “twisted”. This can result in unusual failures.

Designing for Failures

Since these typically are for kits, the most likely failure that will occur is a pulled up trace. This is when the trace on the two boards doesn’t break, and starts pulling up traces inside your layout. Not good. Fortunately, the design can account for this in several ways.

Any of these techniques will generate a “stress concentration point” for a pulled up trace. This will cause a the trace to tear in a well-defined place, ensuring that it won’t affect your board.

The simplest one simply having vias near the tab, as seen on the sparkfun board above. A ripped up trace will usually break at the edge of the via pad.

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Another option is to actually narrow the trace near the board edge. This takes up less space than a via, but still provides a good weak point in a desirable location. However, make sure you don’t go too far below the design rules!

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The last option is less ideal, but may suit certain layouts. Simply jog the trace, creating a 90° bend or two.

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Indicating on the design

Here’s the measurements on our typical support tabs. Your design may require different configurations, so these are a rough guideline.

Typical tabs have the following features

  • 20-25 mil drill hits
  • 20-25 mil between the edge of the drilled holes
  • roughly a 40 mil drill pitch
  • 2-5 holes per tab (3-4 recommended)
  • Holes tangent to the original board outlines

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Note, the milling tool will add a 34 mil corner radius on the tabs. As a result, you can place the outermost holes tangent to the tab edge.

Failure modes (and how to cope)

  • Pulled up traces? Need to add a break closer to the edge, or score the board before snapping. Try to handle this on a design revision before a full kit.
Protosnap

Friday Hack Chat: Eagle PCB Design with Matt Berggren

Eagle is a household name for all Hackaday regulars. Here’s your chance to learn about upcoming features, get your ‘how do I do this in Eagle?’ questions answered, and get your wishlist items heard. Join us on Friday at 12:00 PST for a live Hack Chat about the Eagle PCB Design software. Hosting this week’s…

via Friday Hack Chat: Eagle PCB Design with Matt Berggren — Hackaday

Friday Hack Chat: Eagle PCB Design with Matt Berggren

Building Beautiful Boards With Star Simpson

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Star Simpson, creator of Circuit Classics, gave this excellent talk at Hackaday Supercon:

Building Beautiful Boards With Star Simpson

Over the last decade or so, the cost to produce a handful of custom PCBs has dropped through the floor. Now, you don’t have to use software tied to one fab house – all you have to do is drop an Eagle or KiCad file onto an order form and hit ‘submit’.

Building Beautiful Boards With Star Simpson

ESPTool: WiFi Security Swiss Army Knife

Daniel Grießhaber created this convenient tool to test your WiFi Security against attackers:

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ESPTool

Demonstrate how easy it is to crack a WiFi Password or jam your WiFi so you can’t access the internet.  Designed for education and self-tests.

ESPTool has the following hardware:

  • SSD1306 based OLED Display, connected via I2C
  • microSD Card Socket connected over the SPI interface
  • 3 general purpose buttons
  • ESP8266-12E Module
  • TPS63031 Buck-/Boost-Converter with an input range from 1.8V – 5.5V
  • MCP73831 Single-Cell LiPo Charger Chip
  • CP2012 USB to UART converter Chip

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The design files and source code are available on GitHub:

images11dangrie158/ESPTool

ESPTool: WiFi Security Swiss Army Knife

Open Source AIS Transponder

Automatic identification system (AIS) is an automatic tracking system used on ships.  Peter Antypas designed a low-power AIS transponder:

images1 Open Source AIS Transponder (Class B)

This is the first ever (that I’m aware of) attempt at creating an open source AIS transponder

Hardware:

On the hardware side, the design is based on two Silicon Labs 4463 transceiver ICs and an STM32F302CBT6 ARM Cortex M4 microcontroller. One of the SiLabs ICs acts as a transceiver, while the other IC works as a receiver only. In receiver mode, each IC tunes to a different channel. When a transmission is scheduled, the ICs swap channels if the transceiver is not listening on the next transmit channel. This configuration may be construed as a violation of the AIS specification, but it makes for a much simpler PCB layout and negates the need for a 3-position RF switch.

Software:

There are two programs that need to be installed on the flash. The bootloader and the main application.

petera650 has shared the boards on OSH Park:

RF side of AIS transponder

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Order from OSH Park

Logic / digital side of AIS transponder

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Order from OSH Park

Open Source AIS Transponder