How to find an embedded platform? - embedded

I am new to the locating hardware side of embedded programming and so after being completely overwhelmed with all the choices out there (pc104, custom boards, a zillion option for each board, volume discounts, devel kits, ahhh!!) I am asking here for some direction.
Basically, I must find a new motherboard and (most likely) re-implement the program logic. Rewriting this in C/C++/Java/C#/Pascal/BASIC is not a problem for me. so my real problem is finding the hardware. This motherboard will have several other devices attached to it. Here is a summary of what I need to do:
Required:
2 RS232 serial ports (one used all the time for primary UI, the second one not continuous)
1 modem (9600+ baud ok) [Modem will be in simultaneous use with only one of the serial port devices, so interrupt sharing with one serial port is OK, but not both]
Minimum permanent/long term storage: Whatever O/S requires + 1 MB (executable) + 512 KB (Data files)
RAM: Minimal, whatever the O/S requires plus maybe 1MB for executable.
Nice to have:
USB port(s)
Ethernet network port
Wireless network
Implementation languages (any O/S I will adapt to):
First choice Java/C# (Mono ok)
Second choice is C/Pascal
Third is BASIC
Ok, given all this, I am having a lot of trouble finding hardware that will support this that is low in cost. Every manufacturer site I visit has a lot of options, and it's difficult to see if their offering will even satisfy my must-have requirements (for example they sometimes list 3 "serial ports", but it appears that only one of the three is RS232, for example, and don't mention what the other two are). The #1 constraint is cost, #2 is size.
Can anyone help me with this? This little task has left me thinking I should have gone for EE and not CS :-).
EDIT: A bit of background: This is a system currently in production, but the original programmer passed away, and the current hardware manufacturer cannot find hardware to run the (currently) DOS system, so I need to reimplement this in a modern platform. I can only change the programming and the motherboard hardware.

I suggest buying a cheap Atom Mini-ITX board, some of which come with multi - 4+ RS232 ports.
But with Serial->USB converters, this isn't really an issue. Just get an Atom. And if you have code, port your software to Linux.
Here is a link to a Jetway Mini-Itx board, and a link to a 4 port RS232 expansion module for it. ~$170 total, some extra for memory, a disk, and a case and PSU. $250-$300 total.
Now here is an Intel Atom Board at $69 to which you could add flash storage instead of drives, and USB-serial converters for any data collection you need to do.
PC104 has a lot of value in maximizing the space used in 19" or 23" rackmount configurations - if you're not in that space, PC104 is a waste of your time and money, IMHO.

The BeagleBoard should have everything you need for $200 or so - it can run Linux so use whatever programming language you like.

A 'modern' system will run DOS so long as it is x86, I suggest that you look at an industrial PC board from a supplier such as Advantech, your existing system may well run unchanged if it adheres to PC/DOS/BIOS standards.
That said if your original system runs on DOS, the chances are that you do not need the horsepower of a modern x86 system, and can save money by using a microcontroller board using something fairly ubiquitous such as an ARM. Also if DOS was the OS, then you most likely do not need an OS at all, and could develop the system "bare-metal". The resources necessary just to support Linux are probably far greater than your existing application and OS together, and for little or no benefit unless you intend on extending the capability of the system considerably.
There are a number of resources available (free and commercial) for implementing a file system and USB on a bare-metal system or a system using a simple real-time kernel such as FreeRTOS or eCOS which have far smaller footprints than Linux.

The Windows embedded site ( http://www.microsoft.com/windowsembedded/en-us/default.mspx )
has a lot of resources and links to hardware partners, distributors and development kits. There's even a "Spark" incubation project ( http://www.microsoft.com/windowsembedded/en-us/community/spark/default.mspx )
What's also really nice about using windows ce is that it now supports Silverlight as a development environment.

I've used the jetway boards / daughter cards that Chris mentioned with success for various projects from embedded control, my home router, my HTPC front end.
You didn't mention what the actual application was but if you need something more industrial due to temperature or moisture constraints i've found http://www.logicsupply.com/ to be a good resource for mini-itx systems that can take a beating.
A tip for these board is that given your minimal storage requirements, don't use a hard drive. Use an IDE adapter for a compact flash card as the system storage or an SD card. No moving parts is usually a big plus in these applications. They also usually offer models with DC power input so you can use a laptop like or wall wart external supply which minimizes its final size.
This http://www.fit-pc.com/web/ is another option in the very small atom PC market, you'd likely need to use some USB converters to get to your desired connectivity.
The beagle board Paul mentioned is also a good choice, there are daughter cards for that as well that will add whatever ports you need and it has an on board SD card reader for whatever storage you need. This is also a substantially lower power option vs the atom systems.
There are a ton of single board computers that would fit your needs. When searching you'll normally find that they don't keep many interface connectors on the processor board itself but rather you need to look at the stackable daughter cards they offer which would provide whatever connections you need (RS-232, etc.). This is often why you see just "serial port" in the description as the final physical layer for the serial port will be defined on the daughter card.
There are a ton of arm based development boards you could also use, to many to list, these are similar to the beagle board. Googling for "System on module" is a good way to find many options. These again are usually a module with the processor/ram/flash on 1 card and then offer various carrier boards which the module plugs into which will provide the various forms of connectivity you need.
In terms of development, the atom boards will likely be the easiest if your more familiar with x86 development. ARM is strongly supported under linux though so there is little difficulty in getting these up and running.
Personally i would avoid windows for a headless design like your discussing, i rarely see a windows based embedded device that isn't just bad.

Take at look at one of the boards in the Arduino line, in particular the Arduino Mega. Very flexible boards at a low cost, and the Mega has enough I/O ports to do what you need it to do. There is no on-chip modem, but you can connect to something like a Phillips PCD3312C over the I2C connector or you can find an Arduino add-on board (called a "shield") to give you modem functionality (or Bluetooth, ethernet, etc etc). Also, these are very easy to connect to an external memory device (like a flash drive or an SD card) so you should have plenty of storage space.
For something more PC-like, look for an existing device that is powered by a VIA EPIA board. There are lot of devices out there that use these (set-top boxes, edge routers, network security devices etc) that you can buy and re-program. For example, I found a device that was supposed to be a network security device. It came with the EPIA board, RAM, a hard drive, and a power supply. All I had to do was format the hard drive, install Linux (Debian had all necessary drivers already included), and I had a complete mini-computer ready to go. It only cost me around $45 too (bought brand new, unopened on ebay).
Update: The particular device I found was an EdgeSecure i10 from Ingrian Networks.

Related

Hacking computer hardware to do experiment control

I am a physicist, and I had a revelation a few weeks ago about how I might be able to use my personal computer to get much finer control over laboratory experiments than is typically the case. Before I ran off to try this out though, I wanted to check the feasibility with people who have more expertise than myself in such matters.
The idea is to use the i/o ports---VGA, ethernet, speaker jacks, etc.---on the computer to talk directly to the sensors and actuators in the experimental setup. E.g. cut open one side of an ethernet cable (with the other end attached to the computer) and send each line to a different device. I knew a postdoc who did something very similar using a BeagleBone. He wrote some assembly code that let him sync everything with the internal clock and used the GPIO pins to effectively give him a hybrid signal generator/scope that was completely programmable. It seems like the same thing should be possible with a laptop, and this would have the additional benefit that you can do data analysis from the same device.
The main potential difficulty that I foresee is that the hardware on a BeagleBone is designed with this sort of i/o in mind, whereas I expect the hardware on a laptop will probably be harder to control directly. I know for example (from some preliminary investigation, http://ask.metafilter.com/125812/Simple-USB-control-how-to-blink-an-LED-via-code) that USB ports will be difficult to access this way, and VGA is (according to VGA 15 pin port data read and write using Matlab) impossible. I haven't found anything about using other ports like ethernet or speaker jacks, though.
So the main question is: will this idea be feasible (without investing many months for each new variation of the hardware), and if so what type of i/o (ethernet, speaker jacks, etc.) is likely to be the best bet?
Auxiliary questions are:
Where can I find material to learn how I might go about executing this plan? I'm not even sure what keywords to plug in on Google.
Will the ease with which I can do this depend strongly on operating system or hardware brand?
The only cable I can think of for a pc that can get close to this would be a parallel printer cable which is pretty much gone away. It's a 25 wire cable that data is spread across so that it can send more data at the same time. I'm just not sure if you can target a specific line or if it's more of a left to right fill as data is sent.
To use one on a laptop today would definitely be difficult. You won't find any laptops with parallel ports. There are usb to parallel cables and serial to parallel cables but I would guess that the only control you would have it to the usb or serial interface and not the parallel.
As for Ethernet, you have 4 twisted pair with only 2 pair in use and 2 pair that are extra.
There's some hardware that available called Zwave that you might want to look into. Zwave will allow you to build a network of devices that communicate in a mesh. I'm not sure what kind of response time you need.
I actually just thought of something that might be a good solution. Check out security equipment. There's a lot of equipment available for pc's that monitor doors, windows, sensors, etc. That industry might what your looking for.
I think the easiest way would be to use the USB port as a Human Interface Device (HID) and using a custom built PIC program and a PIC that includes the USB functionality to encode the data to be sent to the computer and in that way be able to program it independently from the OS due to the fact that all mayor OS have the HID USB functionality.
Anyways if you used your MIC/VGA/HDMI whatever other port you still need a device to encode the data or transmit it, and another program inside the computer to decode that data being sent.
And remember that different hardware has different software (drivers) that might decode the raw data in other odd ways rendering your IO hardware dependent.
Hope this helps, but thats why the USB was invented in the first place to make it hardware and os independent.

how can build single board computer like Raspberry Pi for run OS?

my question is : how can build single board computer like Raspberry Pi for run OS ?
user ARM micro processor and debian arm os , can use USB and etc.
like raspberry pi and other single board computer
i search but find nothing for help me !!! :(
The reason you can find nothing is probably because it is a specialist task undertaken by companies with appropriate resources in terms of expertise, equipment, tools and money.
High-end microprocessors capable of running an OS such as Linux use high-pin-density surface mount packages such as BGA or TQFP, these (especially BGA) require specialist equipment to manufacture and cannot reliably or realistically be assembled by hand. The pin count and density necessitates the use of multi-layer boards, these again require specialist manufacture.
What you would have to do if you wanted your own board, is to design your board, source the components, and then have it manufactured by a contract electronics assembly house. Short runs and one-off's will cost you may times that of just buying a COTS development or application board. It is only cost-effective if you are ultimately manufacturing a product that will sell in high volumes. It is only these volumes that make the RPi so inexpensive (and until recently Chinese manufacture).
Even if you designed and had your own board built, that in itself requires specialist knowledge and skill. The bus speeds on such processors require very specific layout to maintain signal integrity and timing and to avoid EMC problems. The cost of suitable schematic capture and board layout software might also be prohibitive, no doubt there are some reasonably capable open source tools - but you will have to find one that generates output your manufacturer can use to set-up their machinery.
Some lower-end 8 bit microcontrollers with low pin count are suitable for hand soldering or even DIP socketing, using a bread-board or prototyping board, but that is not what you are after.
[Further thoughts added 14 Sep 2012]
This is probably only worth doing if one or more of the following are true:
Your aim is to gain experience in board design, manufacture and bring-up as an academic or career development exercise and you have the necessary financial resources.
You envisage high production volumes where the economies of scale make it less expensive than a COTS board.
You have product requirements for specific features or form-factor not supported by COTS boards.
You have restricted product requirements where a custom board tailored to those and having no redundant features might, in sufficient volumes be cost-effective.
Note that COTS boards come in two types: Application modules intended for integration in a larger system or product, and development boards that tend to have a wide range of peripherals, switches, indicators and connectivity options and often a prototyping area for your own use.
I know this is an old question, but I've been looking into the same thing, possibly for different reasons, and it now comes up at the top of a google search providing more reasons not to ask or even look into it than it provides answers.
For an overview of what it takes to build a linux running board from scratch this link is incredibly useful:
http://hforsten.com/making-embedded-linux-computer.html
It details:
The bare minimum you need in terms of hardware ( ARM processor, NAND flash etc )
The complexities of getting a board designed
The process of programming the new chip on the board to include bootloaders and then pointing them to a linux kernel for the chip to boot.
Whether the OP wishes to pursue every or just some of these challenges, it is useful to know what the challenges are.
And these won't be all of them, adding displays, graphics and other hardware and interfaces is not covered, but this is a start.
Single board computers(SBC) are expected to take more load than normal hobby board and so it has slightly complicated structure in terms of PCB and components. You should be ready to work with BGA packages. Almost all of processors in SBCs are BGA (no DIP/QAFP). Here is the best blogpost that I recently came across. Its very nicely designed and fabricated board running Linux on ARM processor. Author has really done a great job at designing as well as documenting the process. I hope it helps you to understand both hardware and software side of SBCs.
A lot of answers are discouraging. But, I would say you can do it, as I have done it already with imx233. Its not easy, its not a weekend project. My project link is MyIMX233.
It took me about 4-5months
It didn't cost me much, a small fine tip soldering iron is what I used.
The hard part is learning to design PCB.
Next task would be to find a PCB manufacturer with good enough precision, and prototyping price.
Next task would be to source components.
You may not get it right, I got the PCB right by my 3rd iteration. After that I was able to repeatedly produce 3 more boards all of which worked fine.
PCB Design - I used opensource KiCAD. You need to take care in doing impedance matching between RAM and processor buses, and some other high speed buses. I managed to do it in 2 layer board with 5mil/5mil trace space.
Component Sourcing - I got imx233 LQFP once via mouser, and once via element14.
RAM - 64MB tssop.
Soldering - I can say its easy to mess up here, but key is patience. And one caution don't use frying pan and solder past to do reflow soldering. I literally fried my first 2 processors like this. Even hot air soldering by a mobile repair shop was also not good enough.
Boot loading image - I didn't take much chance here, just went with Archlinux image by olimex.
If you want to skip the trouble of circuit designing between RAM & processor, skip imx233 and go for Allwinner V3S. In 2017/2018 this would be easiest approach.
Bottom line is I am a software engineer by profession, and if I can do it, then you can do it.
Why not using an FPGA board?
Something with Zynq like the Zybo board or from Altera like the DE0-Nano SoCKit.
There you already have the ARM core, memory, etc... plus the possibility to add the logic you miss.

What's the best description for "embedded hardware system"?

When I hear that, I always think about an mobile device. But why is the hardware "embedded" there? Isn't the whole device the hardware? Why is a personal computer no embedded hardware system?
In today's world embedded simply refers to a system with one or more of the following traits:
Single purpose (ie, not a general purpose computer, like your desktop)
Firmware rather than software - still software, but not as easily updated (flash, etc)
Hardware and software are designed together as a unit
Different, perhaps more rigorous testing as software updates are not desired
Real time computing
Memory integrated on the CPU
Microcontroller rather than microprocessor
Expected high reliability (you shouldn't have to reboot your dishwasher or microwave)
If it runs a program, but doesn't look like a computer, it's an embedded system.
That's my standard answer for friends and family. There's too many different types of embedded systems to get more specific.
I worked in the "embedded" area for a while and we considered anything that we had to write custom code for the hardware to be embedded.
If you have to work around the memory structure, write custom device drivers and anything that sits "directly on the metal" is generally "embedded".
If you're debugging it via a serial port - it's embedded.
It is called "embedded" because the computer is embedded as part of a larger device.
There is a very wide range of embedded systems.
At the low end are 8-pin PICs, for example there is a 12F629 in these diode lights. These costs cents and have very little memory.
The NXT by LEGO contains two controllers, a relatively big AT91SAM7S256 with a 32-bit ARM core, 256KB of flash ROM and 64KB of RAM, and a smaller 8-bit ATmega48 with 4KB of flash.
Currently I'm working on embedded systems for trains, these typically have a PowerPC with some hundreds of MHz clock, on the order of a hundred MB of RAM, run VxWorks or Linux and are connected by Ethernet.
I think there are still more powerful embedded systems for telecommunications, but I haven't worked on these.
As per Wikipedia:
An embedded system is a
special-purpose computer system designed to perform one or a few
dedicated functions, often with
real-time computing constraints. It is
usually embedded as part of a complete
device including hardware and
mechanical parts. In contrast, a
general-purpose computer, such as a
personal computer, can do many
different tasks depending on
programming.
Embedded systems are designed to do some specific task, rather than be a
general-purpose computer for multiple
tasks. Some also have real-time
performance constraints that must be
met, for reasons such as safety and
usability; others may have low or no
performance requirements, allowing the
system hardware to be simplified to
reduce costs.
Embedded systems are not always standalone devices. Many embedded
systems consist of small, computerized
parts within a larger device that
serves a more general purpose. For
example, the Gibson Robot Guitar
features an embedded system for tuning
the strings, but the overall purpose
of the Robot Guitar is, of course, to
play music.[2] Similarly, an embedded
system in an automobile provides a
specific function as a subsystem of
the car itself.
The program instructions written for embedded systems are referred to as
firmware, and are stored in read-only
memory or Flash memory chips. They run
with limited computer hardware
resources: little memory, small or
non-existent keyboard and/or screen.
From personal experience, if it's "headless" (i.e. doesn't have an output device like a VDU and relies on something like LED's), if there is a serial port used mainly for debugging and logging and if you often use a logic analyser for debugging, it's embedded.
"Embedded" has become a very diverse term.
I've seen and worked on designs that:
Simply toggled discrete I/O (including LEDs) at fixed intervals
Drivers for hardware solutions (e.g. webcams, wireless com)
Acted as communications translators for board-level I/O (SPI<->I2C<->Rs232<->USB)
[ insert multitude of appliances here ]
Human-controlled electronics (calculator-esque, phone-esque)
System level devices to coordinate actions of other devices.
I also like Dour-High-Arch's comment above:
"Another important difference is that embedded apps may run for years without intervention..."
"Embedded system" is a very broad term and I don't think that it is easy to have a single definition. The word "embedded" actually refers to an industry and not to a "hardware system". The description of embedded systems has changed over the years and it is definitely going to change in the future too.
In early days one would say the embedded systems were only programmed in assembly, but now C is common place and perhaps in the future other languages are used as well. CPUs are getting bigger and bigger, external memories are used all the time and they are many devices considered to be embedded that are not dedicated to a single task, applications can be added to them and the software is easily updated. Watches, gadgets, house appliances, automotive devices, PLCs, motor controllers, weather stations, system monitoring devices are all considered embedded. It is difficult to singe define them all.

USB for embedded devices - designing a device driver/protocol stack

I have been tasked to write a device driver for an embedded device which will communicate with the micro controller via the SPI interface. Eventually, the USB interface will be used to download updated code externally and used during the verification phase.
My question is, does anyone know of a good reference design or documentation or online tutorial which covers the implementation/design of the USB protocol stack/device driver within an embedded system? I am just starting out and reading through the 650 page USB v2.0 spec is a little daunting at the moment.
Just as a FYI, the micro controller that I am using is a Freescale 9S12.
Mark
Based upon goldenmean's (-AD) comments I wanted to add the following info:
1) The embedded device uses a custom executive and makes no use of a COTS or RTOS.
2) The device will use interrupts to indicate data is ready to be retrieved from the device.
3) I have read through some of the docs regarding Linux, but since I am not at all familiar with Linux it isn't very helpful at the moment (though I am hoping it will be very quickly).
4) The design approach, for now at least, it to write a device driver for the USB device then a USB protocol layer (I/O) would reside on top of the device driver to interpret the data. I would assume this would be the best approach, though I could be wrong.
Edit - A year later
I just wanted to share a few items before they vanish from my mind in case I never work on a USB device again. I ran into a few obstacles when developing code and getting it up and running for the first.
The first problem I ran into was that when the USB device was connected to the Host (Windows in my case) was the host issues a Reset request. The USB device would reset and clear the interrupt enable flags. I didn't read the literature enough to know this was happening, thus I was never receiving the Set-Up Request Interrupt. It took me quite a while to figure this out.
The second problem I ran into was not handling the Set-Up Request for Set_Configuration properly. I was handling it, but I was not processing the request correctly in that the USB device was not sending an ACK when this Set-Up Request came in. I eventually found this out by using a hardware USB protocol analyzer.
There were other issues that I ran into, but these were the two biggest ones that took me quite a while to figure out. The other issue I had to worry about is big-endian and little-endian, Freescale 9S12 vs USB data format (Intel), respectively.
I ended up building the USB device driver similar to UART device drivers I had done in the past. I have posted the code to this at the following URL.
http://lordhog.wordpress.com/2010/12/13/usb-drive
I tend to use structures a lot, so people may not like them since they are not as portal as using #defines (e.g., MAX3420_SETUP_DATA_AVAIL_INT_REQR 0x20), but I like them since it makes the code more readable for me. If anyone has questions regarding it please feel free to e-mail and I can try to give some insight to it. The book "USB Complete: The Developer's Guide" was helpful, so long as you knew what areas to concentrate on. This was a simple application and only used low-speed USB.
While writing a device driver for any interface (USB, Parallel port, etc...) the code needed to be developed would depend upon whether there is any Operating System(OS), RTOS running on that Processor/Micro controller.
e.g. if thats going to run say WinCE - It will have its own Driver development Kit , and steps to be followed in the device driver development. Same for any other OS like Linux, symbian.
If its going to be a plain firmware code(No OS) which is going to control the processor/microcontroller, then it's a different situation altogether.
So based on either of the above situation u are in, one needs to read & understand:-
1.) The Hardware Specification of the processor/micro controller development board - Register files, ports, memory layout, etc.
2.) USB spec
3.) Couple of pointers i found quickly. Google shud be ur friend!
http://www.lrr.in.tum.de/Par/arch/usb/usbdoc/ - Linux USB device driver
http://www.microsoft.com/technet/archive/wce/support/usbce.mspx
-AD
I've used an earlier edition of USB Complete by Jan Axelson. Indeed very complete.
From the editorial review:
Now in its fourth edition, this developer's guide to the Universal Serial Bus (USB) interface covers all aspects of project development, such as hardware design, device firmware, and host application software.
I'm curious, why did you pick the 9S12? I used it at a previous job, and was not pleased.
It had lousy gcc support so we used Metrowerks
which may have been okay for C, but often generated buggy C++
had a lousy IDE with binary project files!
The 9s12 was also slow, a lot of instructions executed in 5 cycles.
Not very power efficient, either.
no barrel shifter, made operations that are common in embedded code slow
not that cheap.
About the only thing I dislike more is an 8051. I'm using an ARM CortexM3 at my current job, it's better than a 9S12 in every way (faster clock, more work done per clock, less power consumption, cheaper, good gcc support, 32-bit vs. 16-bit).
I don't know which hardware you're planning to use but assuming that's flexible, STMicro offers a line of microcontrollers with USB/SPI support and a library of C-code that can be used with their parts. -- I've used their ARM7 series micros for years with great success.
Here is an excellent site maintained by Jonathan Valvano, a professor at the University of Texas. He teaches four courses over there (three undergraduate, one graduate), all are about using a 9S12 microcontroller. His site contains all the lecture notes, lab manuals, and more importantly, starter files, that he uses for all his classes.
The website looks like it's from the 90's, but just dig around a bit and you should find everything you need.
users.ece.utexas.edu/~valvano/
Consider AVR for your next MCU project because of it's wonderful LUFA and V-USB libraries.
I'm working on a project using the Atmel V71. The processor is very powerful and among lot's of high end connectivity offered on chip is a USB engine that will do device or host modes for 480 Mhz or 48Mhz (not USB 3.0). The tools are free and come with a number of host and device USB example projects with all the USB stack code right there. It supports 10 end points and all the transfers are done via DMA so you have most of the processor horsepower available for other tasks. The Atmel USB stack works without needing an RTOS

GPS and Embedded Development - Where to find resources?

I'm just starting to design some embedded devices, and am looking for resources.
What I want to be able to do is to connect a GPS receiver to a lightweight SBC or mini-ITX, x86-based computer, and track a remote-controlled vehicle's location/progress.
Ideally, this could morph into building some hobby, semi-autonomous vehicles.
But what I need to start with is a development board for GPS programming.
What boards/packages have you used, and where can I find [preferably open source] development for them?
OpenEmbedded is a good place to go to get started. A lot of embedded products use ARM and other processors, so cross-compiling is a big deal. Buildroot is another resource for building custom linux kernels for small systems.
You can also find lots of manufacturers with Single Board Computers (SBCs) that have tools to do what you want - do a google search for "SBC Linux" and you should have a gold mine.
LinuxDevices keeps a pulse on the linux embedded community and you should find several good articles there that lead you to products or software to help you.
Debian has an embedded build, but I haven't explored that.
There are several books on embedded linux available if you want to go that route.
The GPS receiver simply connects to a serial or USB port, and present an NMEA stream of data, which you can parse with GPSD and several programs can access it through GPSD. It's a very simple text based format.
I've used regular PC motherboards, and Atmel AT91 processors for embedded systems (with GPS, cellular, etc). There's a lot of information out there right now, and it's not expensive to get into. If I were to start a new project, I'd look at the AVR32 processors from Atmel - they are very hobbyist friendly, and provide a lot of community support for linux on the AVR32 architecture. They provide free GCC compilers and significant framework and examples if you want to go the OS-less route and have a single program running on the processer as well.
Good luck!
-Adam
"NMEA" is the keyword to be searching for when looking for this stuff. While I haven't done anything with this in a long, long time, here is a good source for some boards and other hardware:
http://www.sparkfun.com/commerce/categories.php?c=4
We have had good luck with Holux GPS recievers (designed for samsung q1). A farily simple connect over serial port and you can read the NMEA string.
What OS are you targeting? If it's Linux there are a lot of GPS libraries available (here's a good list). GPSd and GpsDrive are two of the more popular ones I've seen.
I haven't see any GPS devices specifically for lightweight/embedded use, but many of the consumer GPS devices have USB hookups available that could probably work (watch out for low end ones, they usually don't have the computer interface).
I suggest starting with a plain old c project that reads and parses NMEA from a serial port. You can do this in Windows or Linux.
I usually break down any project like this into a set of smaller projects like:
read and parse NMEA from serial
port
establish a serial /
network link from the remote device
to the tracking system server
integrate the components
Wikipedia has a good article on the NMEA protocol. As Adam points out it's actually pretty simple.
Circuit Cellar magazine often has projects like this as well.
Depending on what you want to do, there are various sizes of target to consider. Use Atmel AVR for small low power (battery) stuff. Perhapse use Linux on an old laptop if I just wanted to rough out the concept and needed WiFi (or cellular) for internet.
The laptop Linux prototype then could be trimmed down and ported to an embedded Cinux system for even lower battery usage and portability later on. (not as low as Atmel though).
If you are comfortable with programming in Linux I would recommend the Gumstix range of small computers - http://www.gumstix.com/
You could pair the vedex motherboard with the GPSstix expansion board tp make a tiny GPS receiver with a well supported programming environment.
I suggest GPSBabel to communicate with your GPS receiver.
GPSBabel
Handles waypoints, tracks, and routes,
Knows lots of format (this explains the name Babel),
Runs on Windows, Linux, OSX,
Free.
Some people here have suggested devices like the gumstix - embedded devices which cost $149 without GPS. I don't understand that bit. A off-the-shelf TomTom comes with running Linux on ARM, built-in GPS, lots of flash, battery and screen. It's hard to beat the price advantage that comes with mass production. For your hobby project, the map included is not needed, but who cares?