An early test result, showing text and millseconds since power-on.
About a year ago, I bought a few 11 digit, 7 segment red LED displays from Active Surplus up on Queen Street in Toronto. (Excellent store. If you’re into hacking stuff at all, it’s well worth the trip. Look for the monkey on Queen street to find their entrance.)
This past week, I wasn’t sure what to do at Interlock on Tuesday night, but I had recently re-found these displays, so I figured I would finally get them working. I hit Radio Shack to get a Seeed Studio Arduino Shield ($10 with a mess of components, probably the best deal in all of Radio Shack.)
The display with a header soldered on, and the shield with its assorted parts.
I was all set to figure out how to reverse-engineer the pinout on the bottom of the display; I googled for the LED module, and found specs on those, and then on a whim, decided to check on the entire module board, a Rohm LU-3011, and found the jackpot, this post about figuring out the pinout. It suddenly became very easy to do this project.
The two key things gleaned from that above post, which I have mirrored here, are this table of enables for each of the 11 digits:
| Digit |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
| Pin |
1 |
2 |
3 |
4 |
6 |
8 |
10 |
12 |
14 |
16 |
18 |
and this image, showing the pin mappings of the segments:
Mapping of the segments to the pins on the header.
The basic way these displays work is that all of the 7 segments (plus one decimal point) are all tied together to the pins specified above. Then the anodes for each of the displays are broken out to the pins in the table above. So to draw a ’7′, you would set all of the segments to LOW, except for pins 11, 19, and 7 which you set HIGH. Then to turn on a specific digit, let’s say digit 11 (rightmost), you set the digit enable pin 18 to be an output, and set it LOW. Set all of the other digit enables to be inputs (tri-state, not low or high), and only position 11 will show a “7″. You repeat this for all of the 11 digits in the display, and you can display 11 full digits from just those 19 pins.
In my code (available below) I start at digit 1, and work down to digit 11, enabling each one, in turn, showing its segments, waiting 1 millisecond, then disable that digit, move on to the next one.
I soldered a pin header on the display, and built up a shield to plug it into.
All of the digit enables wired up. The top ones are a bit messy. Sorry about that.
I wired it up such that the digit enables and segments are wired directly to IO lines on my Arduino. This used all of the IO lines, minus the D13 pin, which has an on-board LED.
The code that I wrote (available below) lets you do arbitrary digits per character, so that i can do (primitive) alphanumerics, or do animation patterns, etc. I also store the decimal point as a separate character going in to the display code, so “3.141″ is five ascii characters going in, but a flag is set on the ’3′ position saying that this digit should also display its decimal point, so it only consumes four digits in the display.
just testing out all of the segments and digits
For now, it displays a nice clock and some animations on my desk, but I plan on changing it around a little in the near future. I want to use the D13 line as one of the segment enables (probably decimal point) and move the segment enables off of the Serial Receive line. That way i will be able to control it via serial to display patterns, animations or text content. Since the hardware serial port is hardwired to 0 and 1, and I will be using the TX line for the LED displays, I’ll have to instead use the Software Serial, with only its Receive line mapped to an IO pin, and its Transmit line mapped to junk. I’ve done this before and it works well.
The code for this project is available in my Geodesic Sphere github repository.
This post is also available on my personal project blog thing.
from BleuLlama on May 17th, 2013
0 Comments
Transcription of the talk given at BarCamp Rochester on April 20th, 2013, by Skip Meetze.
Hello. My name is Skip. I’m an inventaholic. I am compelled to invent things for reasons that I can not control. I would like to welcome you to Inventaholics Anonymous.
Over the past 40 years, I have followed a path familiar to many people with my affliction by accumulating as many patents as I could. But with the help of my new friends at INTERLOCK, I have overcome those tendencies, and I am proud to say that I have moved on to the sober world of hackers and makers. A world known as the Open-Source Hardware Movement.
First Patent: The Stepcounter
In many ways, being an inventor has scarred my life. In the early 1970s I squandered all the funds I could beg or borrow (at least I didn’t steal), and I blew it all on my first patent. The Stepcounter was a research device to measure the activity levels of laboratory animals. My wife wanted to make the down payment on a house. Thanks to my addiction, we rented for 25 years before we bought our first house.
Kenneth Brown, the author of a book called Inventors at Work asked my old friend, the late Bob Gundlach an important question during an interview: “Is it better to be an inventor working for a large corporation, or would you rather be working on your own?” I can relate to Bob’s answer: “Being an inventor on your own is a good way to go broke! Being an inventor in a corporation is a very fortunate happenstance.”
But even within a corporation you run into the Not Invented Here Syndrome. If you offer a solution to improve a product that is outside of your assigned responsibilities, you will probably be rebuked with something like “No thanks. I’ve got my own ideas and I know what I’m doing. Go work on your own assignment.”
vue-stand
I graduated from Xerox a few years ago and in 2010, my friend Ken and I invented a stand for iPads that we called the vue-stand. It would hold your iPad at a comfortable eye-level. As a human factors engineer I have spent decades designing easy-to-use products, and I thought that we were onto something. After we spent thousands of dollars to do a pilot run at manufacturing and did a little test market, I couldn’t help remembering Bob’s words of wisdom. People didn’t buy the vue for reasons we now understand. We decided not to keep throwing money at trying to market a dead horse, so I bought out Ken’s interest in our company, and I continue selling off my inventory online without promotion. That inventory will cut my losses, but it will not cover my investment.
Last summer something happened that changed my life: A couple of guys from this Hackerspace called INTERLOCK Rochester gave a talk at AppleCIDER, a local Apple Computer Users Group. They demonstrated a little desktop 3D printer that they had built themselves. I was blown away.
I knew about Stereolithography and CAD (Computer-aided design). Xerox engineers had made rapid prototypes using that technology for decades. But specialist operated those machines, and they had talent and training that I didn’t have. Furthermore, the machines cost more money than an individual could afford.
Now, people are building these little machines that can even build parts to replicate themselves. And people are sharing their designs and discoveries for other people to build upon. The source code for anything built on these little industrial robots can be shared online at a site called Thingiverse.com.
They call the shared technology RepRap for replicating rapid prototyping. The designs are evolving unbelievably fast because people are sharing with each other! What a sobering thought!
I don’t plan to get any more patents. Now I have a reprap machine, and I have joined the people who share ideas in a Hackerspace.
I used to think of hackers as being the bad guys who stole identities and maliciously created computer viruses and things like that. Now it has come to mean people who take an existing good idea and hack on it to make it better.
iPad on a HandleStand
For instance, I have hacked-up an iPad accessory that I call the HandleStand. I took a protective iPad case that I bought on Amazon for $8 and hacked it. I drilled two holes and attached a pair of hinged handles to it with screws. The case I chose also allows me to attach a Keyboard that protects the front of my iPad.
The handles open up to make a stand that allows the iPad to tilt at any angle. Great for making videos or calling people on FaceTime with the iPad camera that can be pointed in any direction. By the way, it also holds the iPad at a comfortable eye level just like the vue-stand. But it is better for all these reasons.
Where can you buy this HandleStand and how much does it cost? Sorry, but you can’t buy one. You can get the source code from Thingiverse however, and if you can get access to a 3D printer you can make your own! You can even hack it to make a better one!
You don’t have a 3D printer? Well come on over to INTERLOCK on any Tuesday or Thursday night and we will help you hack one up.
I must admit that getting these little printers to run is a bit tricky sometimes. They are complex electronic devices that run on an open source micro-controller called Arduino. The hardware and software are made from the contributions of many-many people, and instructions don’t necessarily keep up with the latest developments. A lot of things can go wrong, and Murphy’s law does apply.
But hackerspaces are springing up all around the world where people help each other with things like that. So you should join the world of hardware hackers. Free CAD software has gotten so easy to use now that even I could learn it.
Pretty soon most people will know how to design using CAD just like now most people can make Powerpoint presentations. Perhaps it won’t be long before most people will have access to a 3D printer. I built one from a kit for a little over $500. Or you can get a MakerBot already assembled for $2000.
I no longer spend a lot of money trying to sell inventions, I give them away and save a lot of money. My designs can no longer be stolen from me. I’m publishing the source codes on Thingiverse and I am happy that people are downloading them for free.
People tell me that I’m missing an opportunity to make money on my inventions… I don’t care. I’m an inventaholic.
from MacGyvrBot on April 21st, 20130 Comments
If you have access to a 3D printer you can make this!
This is an Open-Source design, and the STL files can be downloaded from Thingiverse: http://www.thingiverse.com/thing:64811
* * *
The HandleStand is hacked from an inexpensive protective case by adding a pair of 3D printed handles.
As the name implies, the accessory provides both a handle and a stand function for the iPad, but it is also quite portable, and the handle can be folded out of the way.
The assembly also accommodates a shoulder strap, a magnetically attached “Smart Cover” or keyboard.
* * *
The A-Frame stand gets the iPad screen up to a comfortable eye-level. A recent study at Harvard concludes: “Head and neck posture during tablet computing can be improved by placing the tablet higher to avoid low gaze angles (i.e. on a table rather than on the lap) and through the use of a case that provides optimal viewing angles.” http://iospress.metapress.com/content/x668002xv6211041/fulltext.pdf
* * *
“But how can I print a handle big enough for an iPad on my little printer that has a 6″ x 6″ bed?” you ask.
Well the answer is: “solvent bonding”… I use Oatey cleaner that is sold in hardware stores to be used on plastic plumbing pipes.
* * *
The trick is to design the device in pieces that are small enough to be printed, and they also must fit together precisely. Then you print them in ABS plastic which can be bonded with solvent to form a solid piece of plastic!* (Please see the WARNING below!)
* * ** * *
I carry my HandleStand with me everywhere!
* * *
With the HandleStand, an iPad can be adjusted to any position about the horizontal or vertical axis, so it is great for FaceTime or shooting video.
The iPad is protected when conveniently carried using the handles or when on a shoulder strap or when folded and stuffed into a backpack or briefcase.
* * *
Instructions
The iPad HandleStand is made up of parts that are small enough to be printed in 3 runs on a PrintrBot LC (which has a usable print area of 120mm x 130mm). The plastic parts are solvent bonded to create handles that are too large to fit on the printer bed.
The Hinge Set contains 2 brackets and 2 sets of A-Frame hinge members. The brackets are screwed onto a polycarbonate protective cover such as the Poetic Basic Smart Cover Slim-Fit Case.
Each bracket is also screwed to a pair of the A-Frame hinge members with o-rings providing the controlled friction for the hinges. Locknuts insure that the hinges stay adjusted and don’t come off.
The Hinge Set takes about 2hr to print on a Printrbot LC with ABS. Handles each contain 3 handle parts and a Microbeaner, and they take about 1hr 20min for each to print (for a total of about 5hr printing time). ABS is recommended because it allows the parts to be solvent bonded together. If PLA or other material is used, then superglue (cyanoacrylate) can be used to bond the parts.
* * *
A shoulder/neck strap that is made from printed “microbeaners” and Parachord can be attached.
* * *
Parts list:
-(1) Hinge Set (containing 2 brackets and 4 hinge members).
-(2) Handles (each containing parts for a 3-piece handle and a MicroBeaner for the shoulder strap).
-(1) Polycarbonate iPad case that snaps on at the corners such as amazon.com/PoeticBasic-Smart-Cover-Slim-Fit-Crystal/dp/B007JBN6NQ
-(2) Stainless steel 6-32 x ¾” oval phillips machine screw (attach hinges to brackets)
-(2) flat-head 6-32 x ⅜” machine screw (attach brackets to polycarbonate case)
-(4) 6-32 lock nuts with nylon inserts
-(4) #6 o-ring provide friction for hinges
-(4) #41 o-ring provide friction against a table
-(1) ⅛” parachord 5’ long
* * *
Tools:
-Drill with ⅛” bit and countersink bit
-Solvent to bond ABS such as Oatey cleaner (yellow label white can) made for ABS plumbing pipe (or use acetone or superglue)… See warning below!
-Use match or lighter to burn the cut ends of parachord
* * *
*WARNING:
-Use CAUTION during solvent bonding!
-Use eye protection.
-Work in well ventilated area!
-The solvent dissolves many things, and the wet plastic stains whatever it touches!
-Use latex NOT vinyl gloves!
-Use aluminum foil on work surface!
* * *
Notes:
-Use great care to go back and coat the whole part for a uniform glossy finish (especially if parts were sanded), but do one end and hang to dry (for a few minutes) before doing the other end!
-The solvent can also be used to heal delaminated parts, but BE CAREFUL!
-Countersink the holes drilled in the Poetic case so that the screw heads will not touch the iPad.
-A large rubber band can be added to keep the the Ultrathin Keyboard or Smart Cover closed while the assembly is being carried around.
Enjoy the HandleStand!
from MacGyvrBot on April 6th, 20130 Comments
I’m about to start making the skeleton for my animatronic Tiki-Room Macaw. Rather than futzing with drawing up detailed plans in some cad program, Iv’e decided to instead get the basic shape made, and then just build one out of foam core. My thought was that once I have the shape worked out, I’ll disassemble it and come up with plans for 3d printable parts that can be attached together, and eventually some vacuum formed parts as well for the head and beak, which need to be lightweight… although I’m starting to think that they could all be 3D printed, with a skin stretched over them for feathers and fur, after seeing the posts on Hack-A-Day about using acetone vapor to smooth out parts… anyway..
One of the things I was unsure of was the control linkages, and how the articulation points can be made. It needs to have a few points of articulation to match the birds in the Enchanted Tiki Room:
- Perch rotation – 270 degrees, spins the bird around (not shown)
- Lean – +20, -20 degrees, to lean forward and backward at the point where the legs connect
- Head yaw – +45, -45 degrees back and forth
- Head tilt – +15, -15 degrees up and down
- Beak – 30 degrees, could be all open or all closed (shown in the diagram as 15 degrees)
I was thinking that after I constructed the foam version, I could figure things out from there, but after seeing this post on Hack-A-Day with a “HOG Drive”, I realized I could leverage off of this design for the head linkages.
I chatted with Skip at Interlock, and by the end of this last Tuesday evening, I had two 3-D printed versions of this, using ABS, rather than the PLA material I am more familiar with. (Here’s the Thingiverse link for the design.) Since I wasn’t going to be mounting a motor, we (and by “we” I mean “he”) replaced the motor space with a flat plate with a mounting screw hole. He also replaced the back control arm with just a peg, since the bridge-like shape wouldn’t hold up properly on his printer.
The first print (on the left) has a failed control peg on the center disk. It was adding material onto printed material that didn’t cool yet, so it just kinda globbed up. This was improved by Skip by adding a second post, seen in the second version on the right. He also added some material around the screw holes in the frame, to improve durability.
After printing and having this in my hand, I’m realizing that it won’t quite work for me, although it does give me an excellent starting point. The center disk is too small to mount the head on. It’s only about 1 1/2 inches in diameter. I think I’d want something about 2-3″ in diameter, with plenty of mounting points and space for securing the head ,as well as space for wiring for the beak servo (or linear motor, or solenoid, or whatever). It really showed me the design considerations for actually constructing something, not to mention it really emphasized that whatever design I can think of, I can print… which is pretty futuristically awesome.
But the important thing is that I know have ideas to build on for the final version. I’ll still be constructing a foam core model, and I’ll be using this above design as a kick-off point.
(This post is cross-posted to my personal project blog as well.)
from BleuLlama on March 6th, 20130 Comments
One of the things that I’ve had to do for my re-purposing of the DB15 Stepper Motor controllers is to be able to reliably reprogram them. The early versions of the programmer consisted of just a wire harness with a DB-15 connector on one end, and leads that plugged into the headers on a standard Arduino board. It eventually progressed into an octopus-like wire harness that used another DB15 as the “host” Arduino. This worked well, but is cumbersome. In this post, I’ll highlight the basic circuit used, and the procedure for using it, specifically for this controller board, but the techniques are applicable to other ATmega based micros as well.
The reason for doing all of this work. About 30 or so DB-15 widgets which can be repurposed as Arduino-compatible microcontroller boards. They don’t have all of the IO that a stock Arduino board has, but if your device only needs 6 IO (one of which is analog input), with a potential for another analog input, and 4 more digital outputs with a little work, they’re an excellent free resource at Interlock!
The ICSP (In-Circuit Serial Programmer) is basically a device that takes in a firmware image from a host computer, and uses SPI-based communications with a target device to shove that firmware image into place. For general Arduino use, you can shove the Arduino serial bootloader into place. This is about 1k (for the optimized bootloader aka “Optiboot”) of program space that sits on your micro, next to any sketch that you download to it. When the Arduino powers up or gets reset, this small bit of code will check for a new sketch to download. If it sees something, it will accept it, shove it into program memory and then run it. If it doesn’t, it simply skips over and runs whatever sketch has already been downloaded there.
The ICSP allows you to program in that bootloader. You can also use it to program in your sketch, if you need to reclaim that 1kbyte of space. I’ll get into that later on.
Okay. Let’s get into the hardware for a moment.
Host Connection.
Showing the basic construction for the Arduino-ICSP Host.
Target connection.
Showing how to hook up the D15 to the programming header above. These 6 lines can also be arranged in the 2×3 layout standard on Arduino boards as well, or wired directly to ATMega chips for other applications.
On the Arduino, the pins are mapped as such:
- Digital 13: SCLK (Orange)
- Digital 12: MISO (Yellow)
- Digital 11: MOSI (Violet)
- Digital 10: SS (Green) (Wired to RESET for the programmer, DB15 pin 4)
The circuit to wire up is pretty easy. On the host, there are three status LEDs that the packed-in “ArduinoISP” uses. Heartbeat shows you it’s alive, Programming shows you when it’s programming a target device, and Error tells you when something went wrong — which is also displayed on the host computer.
These three output should be wired through a 220 ohm resistor, to a LED, and tied to ground.
One other thing that may be necessary is to disable the reset circuit on the host Arduino. This is necessary because when the computer connects to the host Arduino-programmer, that micro will reset, and then quickly hop into the “check for new firmware over serial for itself” routine, as explained above. This may often cause failures with the host computer connecting and communicating with the programmer properly. If you disable the reset circuit here, it will never fall into this state, and will remain perfectly stable. The easiest way to disable it, if you’re building it up from scratch, is to disconnect the DTR/Serial based reset trigger completely, leaving the 10k pullup resistor tied to the arduino’s reset line. However, if you’re using a pre-constructed Arduino as the host, you can simply tie the reset line to +5v through a 120 ohm resistor.
Connecting the host to the target is also easy. The target device should be hooked up as a basic arduino — power, crystal clock, etc. Be sure that even if they’re on separate power supplies, that they at least have their grounds tied together. For ease of use, just power the target from the host completely. Past that, simply connect up pins 11, 12, 13 from the host to the target device. This will put both on the same SPI bus. This is how the data will get sent to the target device. Basically, this maps out as SPI-MISO, SPI-MOSI, and SPI-CLOCK. The only other connection you need to do is to hook up pin 10 from the host computer through to the RESET line of the target.
Step 1: hook up power, ground, serial IO, and reset circuitry.
The reset circuit is a 10k pullup resistor to +5v, and a .1uF cap to the reset line.
Next up will be putting a jumper to disable the reset line as explained above.
(Note: this picture is from a different build but shows the same first step)
The DB15 as seen here has pin 1 on the right. The pins are basically: 1) TX, 2) RX, 4) RESET, then +5 and ground on the bottom pins.
The Red LED is the power indicator. The resistor and cap for the reset circuit are visible, as is the jumper for disabling reset on the ICSP widget.
Above you can see the version of this board that I fabbed up for Interlock. It has the FTDI header for connecting to the host computer, and used a pre-programmed DB-15 widget with the ICSP firmware on it. I know this sounds like a chicken-and-egg thing, but once you program your first device using a standard Arduino as the host, it makes sense to program one of these, and use it to replace that board instead. (especially when you have ~100 of them to spare. hehe)
The blue/white/red/white lines from the ICSP widget are equivalent to pins 10,11,12,13 on a standard host Arduino, and those go right into the cable down to the target device. Since pins 9, 8, and 7 were not all able to be broken out to the LEDs, I had to tweak the sketch a little. 8 is the LED on the ICSP widget itself, which is Yellow. The Yellow and Green LEDs on the board (along with their current limiting resistors) are wired up to Analog 2 and Digital 3 (pwm), and these ports are changed accordingly. 8 remains as the error LED, 3 became the green Heartbeat light, and A2 became the new yellow program light.
Ready to roll, with a target device plugged in!
Note the extra prototyping area. This can be for a ZIF socket in the future for other devices, etc.
The full circuit diagram for the D15-hosted programmer, connected to a D15 target.
(The wire colors are the same as the above for reference.)
Once this is all wired up, we can get some firmware down onto that thing. In our case, we have a device that isn’t directly supported by the Arduino IDE, so we need to configure that first.
Two things need to be installed. First is the board definition, second is the optiboot hex file. Both of these content files can be grabbed from my Geodesic Sphere repository. Full instructions are also there as for specific directories on Windows and Mac for doing this installation. The “readme” there shows the text block to drop into your “Boards.txt” file, and where to find that file. You will also need to drop the optiboot.hex file into the “optiboot” folder as well. Once these two steps are done, you can start up the Arduino IDE and you’re ready to program. Let’s also assume that we’ve already externally kickstarted this, and the “Arduino ISP” sketch is already on the host device, and is running properly.
Here’s where it gets confusing. What? You’re not already confused? HERE WE GO!
Fire up the Arduino IDE, and let’s set it for the D15 device. From the “Tools” menu, select “Serial Port” and select your FTDI interface’s serial port name. Next, from the “Tools” menu, select “ATmega168 at 7372800Hz (D15)” from the “Board” menu. This will tell the IDE what our target device is. Now, from the “Tools” menu, select “Arduino as ISP” from the “Programmer” menu. This is all one-time configuration stuff. Now, you can plug in a target D15 widget to the end of the cable seen above, and then select “Burn Bootloader” from the “Tools” menu. A bunch of lights should flash, and you’ll end up with the Arduino bootloader on the target widget!
On the above setup, it’s wired such that you can also use it to test the target. Disconnect the FTDI cable, disconnect the ICSP widget, and move the newly programmed device into the DB15 connector on the board. Adjust the jumper so that “RESET” is enabled. Now plug the DB15 cable back in. This is now the equivalent to using the DB15 as a barebones Arduino. Load up the D15_Test sketch included in the github repository mentioned above. Click the “upload” arrow button, wait a moment, and the LED on the target widget should be blinking. That’s it!
One alternate way you can use this is to program your Arduino code onto the target widget without installing the bootloader. These widgets use an ATMega 168, which has very constrained space, so this might be preferred for larger programs.
Hook it back up in the programmer configuration, with the ICSP widget on the board, the target on the cable, and the jumper set to disable RESET.
From the Arduino IDE, instead of just clicking the “upload” arrow button, hold down the [SHIFT] key, and the text will change from “upload” to “upload using programmer”. It may take a moment longer, but the end result is that you will see the LED blinking on the target widget.
You can use this to program other Arduino-like devices too (ATMega, ATTiny, etc). You will just need to breakout the 6 lines (MOSI, MISO, CLOCK, RESET, +5v, GROUND) to whatever pin header configuration or socket is necessary. Then you can just select the target device from the menu as appropriate (ATmega 168, 328, 5v, 3.3v, etc) and then select “Burn Bootloader” from the menus as above, and it will put the appropriate serial bootloader onto the device for you.
from BleuLlama on March 4th, 20130 Comments
