Forums

Has anyone designed a board running embedded linux?

Started by vorange February 4, 2007
Be it ARM, XScale, PowerPC, MIPS or any other kinda chip?

How difficult is it to design a small prototype board that can boot an
off the shelf embedded linux distro?  Its been something I've been
meaning to try but don't have enough info on how to go about it.

Where does one begin?  And how does a person build and mount these
chips onto the board when many of these chips are all BGA format?

Questions questions everywhere and not a drop to drink!

On Feb 4, 5:07 am, "vorange" <orange...@yahoo.com> wrote:
> Be it ARM, XScale, PowerPC, MIPS or any other kinda chip? > > How difficult is it to design a small prototype board that can boot an > off the shelf embedded linux distro? Its been something I've been > meaning to try but don't have enough info on how to go about it. > > Where does one begin? And how does a person build and mount these > chips onto the board when many of these chips are all BGA format?
The Atmel AT91SAM9260 is available in PQFP 208. It has an ARM926 core with MMU, and external memory interface, so it's suitable for Linux. It also has a ton of useful peripherals included. If you want to get started quickly, there's also a development board for sale ($560 at digi-key).
> Questions questions everywhere and not a drop to drink!
If you want to learn more about setting up the OS, there's an O'Reilly book that may be helpful ("Building Embedded Linux Systems" by Karim Yaghmour, http://safari.oreilly.com/059600222X )
On Feb 3, 11:07 pm, "vorange" <orange...@yahoo.com> wrote:

> How difficult is it to design a small prototype board that can boot an > off the shelf embedded linux distro? Its been something I've been
The more important question to ask first, is why must one begin this project? Whatever the end application is, it is likely that someone already sells a board that can be used as-is or with little modification. Having said that, there are plenty of Linux-capable SoCs - starting at low-end ARM7 devices and moving on up - that do not come in BGA packages. If you must use a BGA device, well... it's not a cheap path to do this at home (because of low yields) but you can use the toaster oven reflow method. There are special stencils sold for rework use that have just a single BGA[xxx] pad pattern on them; you manually put solder on the pads this way, then put the chip down, reflow it, and pray that it self-aligns properly. It is net cheaper to get an external prototyping house to mount the BGAs for you, though.
vorange wrote:

> Be it ARM, XScale, PowerPC, MIPS or any other kinda chip? > > How difficult is it to design a small prototype board that can boot an > off the shelf embedded linux distro? Its been something I've been > meaning to try but don't have enough info on how to go about it. > > Where does one begin? And how does a person build and mount these > chips onto the board when many of these chips are all BGA format? > > Questions questions everywhere and not a drop to drink!
Hi As a electronic hobbyist I have designed two prototypes using Renesas SH3-processor. As the 2.6-kernel already supported above mentioned processor, it was quite straightforward. I designed the board with two CF-connectors so that I could use CF-cards as filesystem and I still have another slot for WLAN or GPRS. As memory I use normal SDRAM. risto
On Feb 4, 6:57 am, Risto Sainio <say...@tee-online.de> wrote:
> vorange wrote: > > Be it ARM, XScale, PowerPC, MIPS or any other kinda chip? > > > How difficult is it to design a small prototype board that can boot an > > off the shelf embedded linux distro? Its been something I've been > > meaning to try but don't have enough info on how to go about it. > > > Where does one begin? And how does a person build and mount these > > chips onto the board when many of these chips are all BGA format? > > > Questions questions everywhere and not a drop to drink! > > Hi > > As a electronic hobbyist I have designed two prototypes using Renesas > SH3-processor. As the 2.6-kernel already supported above mentioned > processor, it was quite straightforward. I designed the board with two > CF-connectors so that I could use CF-cards as filesystem and I still have > another slot for WLAN or GPRS. As memory I use normal SDRAM. > > risto
This open project will be posted soon, still waiting for final decision. I won't have time to build the boards, so it's mostly COTS. But I use 2.6.16 with 200 Mhz Geode (1G Flash, 512M SDRAM), 50MHz Arm (64K flash, 8K SRAM), FTDI USB-Serial, Garmin GPS and Atheros USB-WiFi (may be GSM/GPRS). I am just going the build the pressure sensors, H-bridge controllers and others. Here is a picture of the Engine Processing Unit http://linnix.com/epu.jpg Everything runs off 5V @1A, except for the 12V DC motots.
On Feb 4, 11:59 am, "larwe" <zwsdot...@gmail.com> wrote:
> The more important question to ask first, is why must one begin this > project? Whatever the end application is, it is likely that someone > already sells a board that can be used as-is or with little > modification.
Hello, I would like to learn the process from the ground up. That way I can add and subtract circuits to the board as needed. With the COTS approach, I am powerless if the vendor does a vanishing act on me or if I want certain changes to the board. I'm doing this only for the sake of experimentation & learning btw, nothing commercial in mind.
> Having said that, there are plenty of Linux-capable SoCs - starting at > low-end ARM7 devices and moving on up - that do not come in BGA > packages.
Not that I want BGAs but the SOC's I've seen seem to come in such packages. So I may be forced to use it if I select such chips. Since I am an amateur, I'll avoid it for now. What non-BGA SOC chips can you suggest to me? I would like one where the schematics and software development tools are easily available and inexpensive or free.
> If you must use a BGA device, well... it's not a cheap path to do this > at home (because of low yields) but you can use the toaster oven > reflow method. There are special stencils sold for rework use that
Sounds like hell.
> pray that it self-aligns properly. It is net cheaper to get an > external prototyping house to mount the BGAs for you, though.
Did you mean to say "It is NOT cheaper..." or "It is MUCH cheaper" ? How much would an assembly house charge for mounting 3 or 4 boards with a BGA chip - any idea? Thanks PS : I thought I posted this message but my post got lost. If you receive it twice, just ignore one.
On Feb 4, 8:33 am, "Arlet" <usene...@c-scape.nl> wrote:
> The Atmel AT91SAM9260 is available in PQFP 208. It has an ARM926 core > with MMU, and external memory interface, so it's suitable for Linux.
Hello, thank you for your suggestion. But is there already a linux port for it? Really I'm looking for an SOC chip that is : a) easy to use b) has free/low cost software development tools c) boots linux d) has schematics I can refer to when building a simple board.
> It also has a ton of useful peripherals included. If you want to get > started quickly, there's also a development board for sale ($560 at > digi-key).
Wow that's expensive but I guess that's how development boards go.
> If you want to learn more about setting up the OS, there's an O'Reilly > book that may be helpful ("Building Embedded Linux Systems" by Karim > Yaghmour, http://safari.oreilly.com/059600222X)
I shall check his book out but first I need to get to the stage of deciding on what chip to use. BTW have you ever done any such project yourself? Could you share your experience for the benefit of the group? Thanks
On Feb 4, 2:57 pm, Risto Sainio <say...@tee-online.de> wrote:
> As a electronic hobbyist I have designed two prototypes using Renesas > SH3-processor. As the 2.6-kernel already supported above mentioned > processor, it was quite straightforward. I designed the board with two > CF-connectors so that I could use CF-cards as filesystem and I still have > another slot for WLAN or GPRS. As memory I use normal SDRAM. > > risto
You guys all sound like pros. A question : When you decided on the chip, what schematics/documents did you refer to to build your board? What process did you go through? Did you first work things out on a development board or did you just go straight for the kill and build the board from datasheets? Does Renesas offer basic/simple schematics to refer to when building a board of your caliber? I'd like to download your brain to my HD when you are not busy. Thanks
On Feb 5, 5:16 am, "vorange" <orange...@yahoo.com> wrote:
> On Feb 4, 8:33 am, "Arlet" <usene...@c-scape.nl> wrote: > > > The Atmel AT91SAM9260 is available in PQFP 208. It has an ARM926 core > > with MMU, and external memory interface, so it's suitable for Linux. > > Hello, > thank you for your suggestion. But is there already a > linux port for it? Really I'm looking for an SOC chip that is : > > a) easy to use > b) has free/low cost software development tools > c) boots linux > d) has schematics I can refer to when building a simple board.
Google for linux and AT91SAM9206.
> > It also has a ton of useful peripherals included. If you want to get > > started quickly, there's also a development board for sale ($560 at > > digi-key). > > Wow that's expensive but I guess that's how development boards go.
Depends. It's expensive when your time is free. If somebody's paying you for the time, it earns itself back quickly. It allows you to test the software without worrying about the hardware, and you can use the schematics as a reference for your own design.
> > If you want to learn more about setting up the OS, there's an O'Reilly > > book that may be helpful ("Building Embedded Linux Systems" by Karim > > Yaghmour, http://safari.oreilly.com/059600222X) > > I shall check his book out but first I need to get to the stage of > deciding on what chip to use.
The book can be read on-line, if you want to be cheap.
On Feb 4, 11:11 pm, "vorange" <orange...@yahoo.com> wrote:

> I would like to learn the process from the ground up. That way I can > add and subtract circuits to the board as needed. With the COTS > approach, I am powerless if the vendor does a vanishing act on me or
Many SoCs are on a short lifecycle anyway. Much shorter than for general-purpose parts. Most, if not all, SoCs are designed for some specific application market. Once that market moves on to new technology, non-core users of that chip are left in the cold.
> Not that I want BGAs but the SOC's I've seen seem to come in such > packages. So I may be forced to use it if I select such chips. Since > I am an amateur, I'll avoid it for now. What non-BGA SOC chips can > you suggest to me?
What are your requirements? One 20MHz CPU core with a segmented LCD controller, or a 3.2GHz CPU core, ten co-processors and eight gigabit Ethernet MACs on the one chip?
> I would like one where the schematics and software development tools > are easily available and inexpensive or free.
Most of the chips will have reference schematics available. All of the parts you will be considering will be supported on the software side by the GNU toolchain. Physically connecting your computer to the chip will cost you some money though - probably not much. Olimex for example make some very cheap JTAG bit-bangers for ARM parts.
> > pray that it self-aligns properly. It is net cheaper to get an > > external prototyping house to mount the BGAs for you, though. > > Did you mean to say "It is NOT cheaper..." or "It is MUCH cheaper" ?
I meant to say exactly what I did say: it is, net, cheaper. I.e. when you factor in the cost of replacing or reworking a failed homebrew attempt, it is overall cheaper to get a pro to do it for you.
> How much would an assembly house charge for mounting 3 or 4 boards > with a BGA chip - any idea?
I pay about $80-$100 per board including X-ray inspection. But I only ever do a very few this way.