Over the last few weeks I have been responding to Robbie King's questions about reference design issues (See Patching functions and libraries and USB line termination in mbed LPC11U24). Robbie is turning his mbed NXP LPC11U24 design into a PCB level design, and so wanted to make sure he was building the right thing. It occurred to me that there are probably lots of other mbed users making custom PCBs to take their prototypes to the next level, but we don't often hear about it.
For custom PCB prototypes I have been using Seeedstudio Fusion PCB Service. The one shown here is an LPC11U24 breakout for testing the mass storage boot loader. At 5cm x 5cm, it only cost $9.90 for 10-off, and as I wasn't in a hurry (I have plenty other things to do here at mbed HQ!) the $3 delivery option was fine. The whole thing was $14 delivered.
Seeedstudio recently introduced a gift certificate feature on their site, and have offered some gift certificates for sponsoring some PCBs.
If you'd like to showcase what you've been working on, and maybe win a gift certificate, drop us a line at firstname.lastname@example.org, and tell us a little about the design you're working on, why it is cool, and why you should get your PCBs for free! I'll keep entries open until 18th October (you have a week!), after which we'll award the certificates. Once the PCBs are made, you'll have the opportunity to write a guest blog article showcasing your design!
If you missed Martin Smith's post in the forum about E.R.I.C the robot dog, you might just want to take a look at this:
It is an awesome project, not just because of the finished product, but because the wide range of skills showcased. These range from embedded software development and debug, to the very theoretical/mathematical pursuit of image processing algorithms, to the mechanical aspects of the design with the AX-12 servos, and of course CAD/CAM design, leading up to milling things out of aluminium!
I'd spoken with Martin before a couple of years ago, so didn't feel shy about asking him to do a bit of a write-up. As he'd already kept a very detailed on-line notebook (which I spent a good deal of time reading through!) all I was really asking for was an overview.
As a part of this project Martin has also documented and published under the default MIT license a library for the AX-12 servos used by ERIC. I'd previously make a prototype version of this library, so it was nice to see it given the love and attention it deserves.
I think congratulations are in order to Martin for pulling off such an awesome project, and documenting it so thoroughly.
If anyone else has produced a project of similar quality (either as part of their studies, just for fun, or even as a prototype design in their job) and would be happy to share it in this sort of detail, please drop me a line email@example.com.
But now, it's over to Martins pages :
Asking other mbed users a question, answering those questions and being able to learn from previous questions should be getting easier. We've just released a beta of our new Question and Answer area.
The new area allows users to post questions which other users can vote for. Hopefully voting will mean that interesting questions are easier to find.
Answers can be posted and the person that posted the question can accept an answer. The ability to mark answers as accepted will mean that it is easy to see what worked when reading through old questions and it means that finding unanswered questions will be much easier.
The Question and Answers area is currently only available to beta users but it's easy to enable beta mode if you want to join in. If you're not keen to become a beta tester then you can expect to see the new area in the next few weeks.
The first samples of the mbed Application Board are back from the manufacturers, L-TEK. There are a few minor tweeks to make before we press the "GO" button for full production, but the tests so far have worked great.
The three lucky winners who will get one of these application boards in exchange for writing a driver and associated cookbook page are, in no particular order :
- Erik Olieman - MMA7660 3-axis +/1 1.5g Accelerometer
- Peter Drescher - C12832 Graphics LCD Screen
- Matthew Shoemaker - LM75B I2C Temperature sensor
A big thanks to all the people who applied - Keep your eyes out, we may well do another competition for "the most interesting application"!
Over the coming weeks, libraries, "hello world" examples, cookbook pages and so on will start to appear for the application board, along with the schematics and all of the support materials you'd expect. I'm aiming for it to be available in time for the Christmas rush ;-). I will be working with all your favourite distributors to get it on the shelves and arrange pre-ordering.
In the mean time, a few people asked about the Xbee socket. This has been designed to accept the popular Xbee Zigbee module or the RN-XV wifly module. We've also made sure that the USB Host socket can be powered externally so that a Vodafone USB Modem can be used. That's a whole lot of wireless communication!
Keep your eyes out for the announcement when they become available, and in the mean time, check out the fully loaded board, complete with Wifi!
For those interested interested in the the minor tweek to be made...
There was a slight error in the footprint for the MMA7660 accelerometer. Some of the copper pads were in the wrong order - very frustrating for a board that was otherwise electrically perfect (Arrrgh!!). If you want to see how I proved the fix, here is a photo from down the barrel of our microscope. That's enamel coated wires from the PCB pads, onto the pads of the devices' DFN-10 3mmx3mm package. I like the occasional challenge!
After a busy year at mbed HQ, I've picked up again on an earlier plan to make a lab board for the mbed NXP LPC1768. Read more about the original concept the blog post entitled On the mbed Whiteboard
Meanwhile, this is the before and after...
We're expecting this to retail at something around $50.
Write a driver, get one free!
The first samples are currently being manufactured so its time to have a little fun. We are offering 3 lab boards free in return for writing one of the 3 peripheral driver libraries required.
These are the 3 peripherals need a good cookbook page
- 128x32 Graphics LCD, Backlit, SPI Interface, Newhaven C12832
- 3 Axis Accelerometer, +/- 1.5g, I2C Interface, Freescale MMA7660
- Temperature sensor, NXP LM75B, I2C Interface
A good cookbook page includes (among other things) :
- Peripheral driver library (Documented with Doxygen, published under default MIT License)
- Hello world program (written by the user, published under default MIT licence)
An example of a good cookbook page is Nokia-LCD.
The other features of the board are :
- Socket for Xbee (Zigbee) or RN-XV (Wifi)
- 5 way navigation switch
- 2 x Potentiometers
- 2 x 3.5mm Audio jack (Analog In/Out)
- 2 x Servo motor headers
- RGB LED, PWM connected
- Speaker, PWM connected
- USB-B connector (keyboard, mouse, MIDI)
- USB-A connector (Flash drive, Bluetooth, GSM Modem(UK Only))
- RJ45 Ethernet connector
- 1.3mm DC Jack input (Powering USB-A and Servo headers)
So, if you are interested in getting one of the 3 first lab boards, email us at firstname.lastname@example.org. Tell us which part you want to write a library for, and send link(s) to examples of your work that's already published.