Saturday, September 14, 2019

Mega Enigma Progress: M4 Works

The four rotor M4 Enigma Machine is working 100%. Now lets get the other 20 machines working.

An interesting thing about this simulator is that it is continuously calculating the path through the rotors for the current key pressed.

The hardware allows for multiple key presses and the software is written to use this functionality. For example, if the key A is pressed, the rotors are advanced when they stop, the result of encrypting that letter is shown. If another key is pressed, the rotors stay put and the result of encrypting that letter is also simultaneously shown on the plugboard.

As in the real machine, the keys must be kept pressed until the rotors stop spinning to illuminate the lampfield. Releasing the key immediately turns off the lampfield. Brief key presses advance the rotors, but do not illuminate the encrypted result.

Another thing that is possible is changing the rotors while a key is pressed. The lampfield is updated to show the new encrypted result for the same key with the current rotor position.

If two keys are pressed and the rotors are changed, the two lamps in the lampfield are updated.

A feature that is still not implemented is turning off the lampfield if a key and its encrypted key are both pressed. Let's say that C is pressed and it encrypts to F, if the F key is also pressed without releasing C, both the C and F lampfield lights should turn off since the Enigma Machine circuitry connects the lamps to the rotor maze through the normally closed contact in the key, pressing that key opens that contact.

The plugboard is also continuously scanned, inserting (or removing) a plug while a key is pressed will update the lampfield if that plug is part of the encryption path.

These features make this simulator one of the most electrically accurate out there.

A bonus feature is that the Mega2560 Pro Mini  at the heart of this project uses the same ATMEGA16U2 as the Arduino UNO for USB connectivity. If you happen to have an External Lamp Field for your original Touchscreen Arduino Enigma, it will work with the Mega Enigma as well.




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Source code:
https://gitlab.com/arduinoenigma/megaenigma

View more pictures on Instagram:
https://www.instagram.com/explore/tags/megaenigma/



Sunday, July 28, 2019

Programmable Seven Segment LED Tester is complete

The conclusion to https://arduinoenigma.blogspot.com/2019/06/a-seven-segment-led-tester.html

Here is the finished Seven Segment Tester. All of the available Arduino Nano pins, except for analog input pins A6,A7 and Serial Port pins D0 and D1 are connected. This leaves us with 18 pins to bring to the 3M Zero Insertion Force (ZIF) socket. Any display up to 9 pin DIP can be tested.

Here are some pictures of the device testing a 16 segment display, a 7 segment display and a 3 digit 7 segment display. The common cathode and common anode versions are programmed as test patterns.

Once the Arduino is programmed, the device can work standalone using a 9v battery.














The base is a reused enigme simulator box lid. 


The OSHPark render of the bottom of the board.


A render of the top of the board. 


The boards as they came from Oshpark.com



Here is a video of the test patterns for a 16-segment LED display and a three-digit seven-segment display.


This design may also be used to test IC, it can supply power and ground to the device under test, put values on some pins and verify that the output from the chip is correct.

Saturday, June 1, 2019

A Seven Segment LED tester

The seven segment displays required for previous projects had, on rare occasions, defective segments. In order to test them all, some contraptions were devised.

Here is a calculator without the displays soldered. Testing the display involved inserting the display in the PCB and running a special program that cycles through all the digits.



This is another rig to test a single seven segment display for the Art Installation Project. This one simply illuminates all the digits simultaneously. The Arduino UNO is simply providing 5V and all the digits are hardwired with jumper wires.



Faced with the prospect of testing the 16 segment displays for the Mega Enigma, building another single purpose jig was not an attractive option.


Most of the Led listings on AliExpress shows the displays being tested on some sort of ZIF socket. We will set to build something that works like that.




The following socket was found:


Here is the datasheet for the socket, we'll design a PCB based on these dimensions and adjust it later if needed.

And here is a preliminary PCB design. It is a very simple design where the bottom 9 pins on the socket are connected to an Arduino Nano.




Here is a preliminary design for a laser cut base. This design shares an edge between two pieces to minimize laser cutting time and therefore cost.


Once the socket arrives, the design for the tester and its base will be finalized. This will be a low cost tester, notice only the bottom 9 pins are wired, and that is good enough for the 16 segment displays. A later design might use the Mega Pro Mini and wire all the segments in the socket.

Tuesday, May 21, 2019

Hackaday Prize 2019

We have three projects running on the Hackaday Prize 2019 this year. 
Two are Enigma Simulators. One, the Z30 has never been made into a physical simulator before.

This year, for every skull you give to these, projects, we get $3, so this is a simple way to show support for these projects. If these get enough skulls, we can order the PCBs and parts for free!!!

Thanks!

https://hackaday.io/project/165684-nano-z30-a-numbers-only-enigma-machine-simulator

https://hackaday.io/project/165559-at-mega-enigma-a-2560-pro-mini-enigma-simulator

https://hackaday.io/project/163549-a-seven-segment-art-installation

All of our projects:
https://hackaday.io/projects/hacker/72667

Saturday, May 18, 2019

Enigma Simulator PCB almost ready for production

The design of the board is almost ready for production. It's been fully routed, all the connections verified, a routing mistake has been found and fixed and the mounting holes are in their final location. All that's left to do before production is some more double checking and cleaning up the bottom silkscreen. Still waiting on the 16 segment displays to arrive, so there is time to check this.


We have the opportunity to do the vias under a key trick again. It is harder to hide all the copper by routing it on the bottom layer on this design, and there are a couple of vias in the display area that are not hidden under a display module. Let's just think that all of these imperfections give this board some character.



A routing mistake was found on the menu button located below the enigma logo. It was wired to the exact same select line/return line combination as the B key, so if unfixed it would have registered as pressing B. 

The fix was simple, the select line above the existing via was unused. All that was needed was to move the via to the next select line. The fix in Fritzing was easy: right click on the bottom wire going from the button to the via and "Delete Wire", right click on the via "Convert Via to Bendpoint", right click on the bendpoint, "Remove Bendpoint". Then create a bendpoint on the next wire, right click on the bendpoint "Convert Bendpoint to Via", drag a wire on the bottom layer from the button to the newly created via and use the parts inspector to set it as "Super Fine (8 mil)" on the bottom layer. 


The resulting fix:


Here are the pin assignments. The 17 pins used to control the display segments are also used to read the keyboard using the KEY1L, KEY2L and UPDNL input pins used as sense lines. This layout allows keys on different sense lines to be pressed simultaneously without corrupting the display. Any single button on the keyboard can be pressed simultaneously with the up/down buttons used to change the rotors. This gives an extra measure of realism by allowing some of the wiring checking procedures on the Merkblatt to be performed. 


The silkscreen labels on the bottom layer need to be cleaned up. This will probably be done last.


Here is the top copper layer. Mostly horizontal lines. The angled lines going to the six lamps on the bottom right stay clear of the silkscreen labels. Six vias are visible on the display area. There will of course be tented. These vias will probably disappear under the shadow of the displays.


Most of the routing action is happening on the bottom layer. To get this clean routing, the board was wired in the following order:

0) layout the components, giving the keyboard and lampfield the characteristic diagonal slant. Place the displays and the up/down select buttons on the right side of the display they control. Place the Arduino Mega 2560 Pro Mini on the top right corner of the board and place a menu button on the top right corner as well.
1) connect the bottom pins of the keys using the top layer
2) connect the bottom pins of the LEDs using the top layer
3) connect the common pins of the up/down select keys using the top layer
4) connect each pin of the (4) 16-segment displays together on the top layer. Weave the traces around and through the display pins. Do not connect the common pins on each display. Those will be individually run later.
5) on the bottom layer, using vertical lines, connect a lampfield LED to the corresponding button in the keyboard (Q light to Q key, W lamp to W key...).
6) on the bottom layer, connect the bottom pins of the top two LED rows together (single trace going from Q to A. This works out to 17 LEDs on one common pin (LED1L).
7) on the bottom layer, connect the bottom pins of the top two keyboard rows together (Q to A again)
8) Starting with pin 2 (leave pins 0 and 1 unused so the Mega2560 serial port works), run traces on the top layer from each of the display pins to the Arduino.
9) Using the bottom layer, connect each LED on the top two rows to individual segment pins on the seven segment displays.
10) Using the bottom layer, connect each LED on the third row to individual segment pins on the seven segment displays.
11) The six LED on the bottom right of the lampfield were too far away from selection lines and long horizontal lines with slants at the end were run on the top layer. The traces are kept away from silkscreen legends. Once those horizontal traces are closer to the left edge of the board, they are run vertically using the bottom layer to the selection lines. Some of the vias are hidden under the displays.
12) Using the bottom layer, route the 2 common sides of the lamp field leds (LED1L, LED2L) and the 2 common sides of the keyboard (KEY1L, KEY2L) to the Arduino. The common side of the Up/Down select buttons (UPDNL) was too close to Arduino pin 46 and was wired horizontally at this point.

Now, all the LEDs and buttons on the main board are wired and this is a functional simulator. By observing the vertical on bottom layer /horizontal on top layer discipline, plenty of space around vertical traces exists to run individual pins to the plugboard connector at the bottom of the board. It is just a matter of selecting a group of 5 or six pins on the Arduino and planning how to route them to the single row connector at the bottom without crossing wires. At some point, we ran out of space to run plugboard wires without using the top layer. A spot was selected under the G key to place a few vias and cross to the other side of the board.

The last thing to do is find a spot to solder the battery wires, the power switch and connect them to the VIN/GND pins on the Arduino.

And by methodically breaking down this task into simple manageable steps, this board is hand routed.


This is how the displays are interconnected. The DRC is not entirely happy with the traces going in between pins, but as long as the red spots look minimal like that, this will manufacture ok.



The holes are placed to support 3mm standoffs. Since board size costs $$$, there is no extra blank space around. The board will sit inside the enclosure walls, not on top.

After a talking to fellow Enigma Simulator Designer @lpaseen (www.meinenigma.com), transient suppression diodes were incorporated into the design of the board. Attention was paid to not placing solder joints on the plug labels.




One of the last steps is to determine that every pin on the Mega2560 is connected to a single pin on the display, a single Up/Down key, and a single LED (which in turn connects to a single key in the keyboard).

The common lines running across the bottom of the LED and keys go into individual pins on the Arduino,

Arduino pin 18 drives Display pin 10 (segment D2, the down key on the rightmost display, LEDs Z, and B, keys Z and B (not shown).

Arduino pin 27 serves as the common (LED1L) for the leds on the top two rows.




Next, map the plugboard connections, double check some more and hit submit...

Saturday, May 11, 2019

Enigma Simulator Fully Routed.

Everything is fully routed and DRC is somewhat happy. About the only thing left to do before ordering the PCB is to finalize the location of the mounting screws.

The next step is to find out what pins connect to each key. When designing this board, the amount of pins was verified to be sufficient, but they are not assigned, instead each device is routed to the most convenient pin and then the software is designed to account for the pin routing.










We don't use the breadboard or schematic view, go straight to routing and check the work very carefully.