Older blog entries for Pizza (starting at number 144)

I made it onto LWN.net's top kernel contributor page!

This week's (Linux Weekly News)[lwn.net) (kernel)[http://lwn.net/Articles/563977] page has information on the upcoming Linux 3.11 release. (Note that this page will be opened up for non-subscribers next week. Subscribe to LWN. They are awesome. Just do it. I'll wait)

I came in at #7 on the top contributor list, with 15,510 lines of code added/changed thanks to the ST-E CW1200 driver getting mainlined. This represents a whopping 1.6% of the overall churn for this kernel release.

While I wasn't the original author of the cw1200 driver (credit for that goes to Dmitry Tarnyagin), over the past couple of years I've rewritten large chunks of its core and substantially tweaked the majority of what's left -- and this mainling effort has taken the better part of a year to accomplish.

But I digress. Getting onto that "top contributors" list was one of those personal/professional milestones that I never expected to attain, especially now that $dayjob has taken me out of the WiFi/802.11 and Linux kernel hacking realms in favor of WPAN ICs with a healthy dose of microcontrollers on the side.

Syndicated 2013-08-22 14:20:42 from Solomon Peachy

linuxaldl hacking continues

My linuxaldl fork now supports bitfield and lookup table data types, though I'm still quite a ways off from testing anything. Further digging into the Pin-E (aka 160bps) signalling shows that it doesn't use RS232-compatible framing:

[160bps pin-E serial interfacing] (http://wbo2.com.au/~techedge.com.au//vehicle/aldl160/160serial.htm)

To make a long story short, a viable solution is to clock the serial port to 10x the actual bit rate, and treat each "byte" received as a single bit, which we'd then translate into 9-bit sequences to decode.

Unfortunately this is completely incompatible with how linuxaldl handles the pin-M (ie 8192baud) protocol, so it looks like I'll need to figure out the best way to do this and probably throw away a couple of prototypes. So it looks like the plug-it-in-and-see-what-happens test is further off than I'd hoped.

Anway, time for bed. Tomorrow I need to put this on hold so I can hunt down a BUG trigger with the cw1200 driver on some SPI hardware. That and I may have some $dayjob work to take home with me too.

Syndicated 2013-08-22 04:11:16 from Solomon Peachy

ALDL hackery, oh my!

One of the upsides to my truck's recent woes is that I ended up with a cable capable of interfacing to its onboard computer. Unlike the "modern" mostly-standardized OBD2 spec (that all 1996+ vehicles were mandated to support) this thing utilizes a GM-specific interface called Assembly Line Diagnostic Link, or ALDL.

General Motors used ALDL between 1982 and 1995, through two major revisions -- 160 baud unidirectional, and 8192 baud bidirectional.

Unfortunately, the physical interface is where the standardization ended -- The logical datastream could be specific to a particular computer, year, model, and drivetrain combination. Oh, there were sometimes additional streams (on physically different pins) for the antilock brake and transmission computers.

All in all, it is quite a mess to deal with, and one that not even General Motors cares about any more. The old Tech1 testers they used to use (and the even rarer data cards) command a pretty steep premium on eBay these days. Cue the aftermarket!

The CD that came with the data cable included various windows-based tools and a pretty comprehensive list of datastream definitions. Initially I used WinALDL to decode the ALDL stream out of my truck. It is fairly old and no longer maintained, which was a problem given that it didn't support the exact datastream my truck spat out. More advanced tools exist (such ass TunerPro), but they target an entirely different audience -- folks trying to reprogram the PROMs in the PCM.

But that's enough background information. Not wanting to have to fire up a Windows instance to talk to my vehicle, I got to thinking that someone out there had to have written an open-source ALDL tool, I did a little poking around and came across LinuxALDL. Unfortunately it turned out to be woefully incomplete -- Its author got things to the point where they WorkedForHim(tm) on his re-engined '88 Fiero, then pretty much abandoned things as they stood.

LinuxALDL was written for the newer 8192 baud bi-directional interface, and while some effort was made to support multiple stream definitions, it wasn't quite completed. It also lacked support for all data types that the ALDL interface exposed.

So, I picked up the code and started hacking away. I've already completed a pile of code cleanups (with more to come), partially implemented support for the low-speed 160-baud interface, and am currently improving the data stream support so I can get niceties like decoded coolant temperature and open-/closed-loop operation flags.

These two things are my main motivation for this work, since the dashboard's temperature gauge isn't linear and I need to know what the actual temperature is, and if the computer is transitioning to closed-loop operation. Even though the PROM I have in there now is tuned for lower temperatures, the truck may actually be running too cool with the electric fans I put in after the radiator blew out last summer. We shall see.

I hope to have things in shape to plug it into the truck tomorrow and see if anything useful comes out. Given that my truck uses the old 160-baud interface, I'll never be able to do anything other than watch/log the data coming out, so once I have both the GUI and command-line datalogging working, I'll probably walk away once I fully expose/decode the my truck's datastream.

Oh yeah, the code. If anyone is intereted, here's my work-in-progress fork of LinuxALDL:

  http://git.shaftnet.org/cgit/users/pizza/public/linuxaldl.git/

Syndicated 2013-08-21 04:08:59 from Solomon Peachy

More microcontroller woes

My good experiences with STMicro's STM32 family and bad experience with the Freescale development "philosophy" got me curious; Where do the other Cortex-M vendors fall along that spectrum?

• STMicro -- Provides straightforward zip files of libraries and code examples.
• Freescale -- Provides an eclipse-oriented environment/code generator as part of a ginormous download, with no meaningful access to libraries or example code. Certian components are windows-only.
• Atmel -- Provides a ginormous development environment only, apparently built on Visual Studio so it's Windows-Only.
• Energy Micro -- Provides a windows-based tool (built using MinGW!) that lets you obtain the core libraries and examples. and the "software download" link on their site is broken.
• NXP -- Provides a straightforward zip file of libraries and code examples.

In other words, Cortex-M vendors are still more tilted towards the tradtional "our-way-or-GTFO" microcontroller vendor approach embodied by Freescale, but they're tending towards the greater openness that ARM is trying to achieve with first CMSIS and now mbed.

In other news, I have my CMSIS microcontroller development framework up and running. It currently supports ARM Cortex-M0, M0+, M3, and M4 cores and the full STM32 (ie F0/F1/L1/W1/F2/F3/F3) family. Adding additional platforms should be pretty easy as long as the vendor supplies a CMSIS port. I'll be adding Energy Micro and NXP ports later today, I hope.

You can find it on my site's git repo

All components, including the (modern GCC/Linaro) toolchain, are suplied in source form and the environment builds and links everything for you.
All you need to do is supply a main() function and take it from there.

Why go through this effort? First, there's no meaningful code or documentation out there on how to leverage the (vastly superior IMO) Unix/GNU toolchain and workflows when workring with Microcontrollers. Tools (even compilers) and development environments tend to be highly proprietary and require inferior operating system platforms. They also tend to target rapid prototyping (And thus have a ton of handholding that gets in the way when you know what you're doing) and tightly lock you in to using that particular vendor's platform, encouraging highly non-portable and non-resuable code. They also tend to encourage horrible development practices.

Heh, I think I've just re-articulated ARM's rationale behind their mbed project. My effort isn't entirely overlapping however; ARM's leveraging C++ to target the rapid prototyping folks first, effectively abstracting all the hardware away, but I'm targetting experienced developers, who want a bare-metal C-oriented approach so you know exactly what's going on.

I don't know how far I'll take this thing; it's almost to the point where it's sufficient for my needs, but I'm releasing it to the world in the hope that others find it useful. I know I'd wished for something like this when I first started hacking on microcontrollers!

Syndicated 2013-08-04 17:50:20 from Solomon Peachy

Freescale vs ST-Micro

Tonight I tried downloading the documentation and sample source code for both Freescale's KL25Z "Freedom" board and ST-Micro's STM32F4 "Discovery" board.

STM's site has its navigational quirks, but all documentation and standard peripheral librares were readily available, with no registration, no hoops, no fuss. Everything I need to build a sample project with four different toolchains is now saved on my workstation.

Freescale's site was better organized, and easier to find information, but they take a very different philosophy when it comes to actually obtaining what you were looking for. First, you have to register, supply a ton of information, and agree to a clickthrough license that basically states you may not actually be allowed to do anything with the code you're downloading.

To top that all off, as I type this their site's CDN is basically shot.
All downloads are glacially slow, with occasional bursts of 4-8KB of data followed by the connections dropping. Even the documentation download wasn't working.

Then they don't have any simple standalone development tools; instead you're stuck either downloading a quarter-gig customized Eclipse package (aka "Procesor Expert Software, Microcontroller Driver Suite").

Assuming I ever get this stuff downloaded, in order to get what I want (namely the CMSIS and peripheral library definitions their MCUs require) I'm going to have to do some serious spelunking since my goal is to use GNU toolchains to create a codebase that isn't completely tied to a single MCU vendor. Or hack, a single MCU from a single vendor, which is what the Processor Export suite seems to accomplish.

No wonder ARM is trying to push the mbed platform; Despite ARM's earlier efforts to standardize ARM MCU programming with CMSIS, Freescale aptly demonstrates the penchance of MCU vendors to shoot themselves in both left feet. mbed standardizes things at a much higher level, effectively abstracting out (and therefore commoditizing) the entire MCU, even the I/Os, generic peripherals, and more esoteric things like clock setup.

Freescale, you have failed. For all your talk of your "freedom" platform, you're doing a piss-poor job of enabling someone to do, well, anything useful with your hardware. (This is especially true for experienced MCU developers!)

In contrast, STM does a pretty good job here; they provide a full standalone peripheral library, including sample applications to drive each peripheral that tie into several different toolchains. They also provide several full-up applications and link to 3rd-party samples, including ensuring that FreeRTOS has first-class support for their parts.

Anyway. Time for bed. Maybe I'll actually get a hello world project generated for the STM32F4 tomorrow. It's obvious that the KL25Z is going to take a lot more work, and I'm beginning to not care enough to put forth the effort.

Syndicated 2013-08-03 04:44:17 from Solomon Peachy

Gutenprint/CUPS unified dyesub backend committed; what's next?

I just committed the unified 'gutenprint+usb' CUPS backend into the upstream gutenprint tree. It ends a two-week-long flurry of slicing and dicing the old standalone backends into a cohesive whole, including fixing the inevitable pile of regressions.

There were also a small pile of (non-regression) bugfixes that made it in, plus the ability to deal with printers that report no serial number (I'm looking at you, Shinko S2145)

Additionally, support for the Kodak 6800 was beefed up, and full support for the Kodak 6850 was added.

This commit pretty much wraps up my task list relating to printers, barring bug reports and/or another printer showing up on my doorstep.

Meanwhile. My next meaty software project is likely to be microcontroller-oriented (ARM Cortex-M series). It's still in the planning stages (a glorified science project) but coming out of it will be skeleton project that others can re-use.

My motivation for this is that if you're entering into the microcontroller world after being used to a typical F/OSS workflow (ie gcc+make+gdb) it's a bit of a shock to discover that IDEs and proprietary tools/libraries are usually crammed down your throat, and there's a dearth of information out there on how to set up a modern hello world project that is written in pure C, is well-documented, and doesn't rely on proprietary bits or third-party "magic handwaving happens here" binaries.

It'll include a modern GCC C/C++ toolchain (via crosstool-ng), debugging support (via OpenOCD and GDB), and a basic FreeRTOS example/port. All of this will be supplied in source code form, even the toolchain.

I haven't decided on how to license this framework, but it'll probably be something ultra-permissive (eg MIT/X) rather than the copyleft (GPLv3) I normally use for software I write.

Syndicated 2013-07-27 12:41:31 from Solomon Peachy

The Kodak 805 works!

I just received the replacement Kodak 805 in the mail. I plugged it in, added its USB ID to the Kodak 1400 backend, and kicked off a test print.

It worked perfectly... and there was a distinct lack of smoke escaping!

In other news, I've fixed the last of the bugs in the Shinko/Sinfonia CHC-S2145 backend, resynced everything with Gutenprint, and now it's time to start unifying the various backends.

This ought to be fun. And by fun, I mean fun. Yeah, I need a life..

Syndicated 2013-07-18 00:14:35 from Solomon Peachy

And the Dyesub printer train continues

The Shinko/Sinfonia CHC-S2145 driver and backend are functionally complete, though bugs remain with the auxilliary commands. I must say it's nice seeing the printer spit out one of my photos in only few seconds, knowing that I wrote much of the driver code. The auxilliary commands work, but there's still something wrong with my handshaking since the printer hangs after the response comes back.

I still have little idea as to the printer error codes, but I found some docs via google that at least enumerate the various errors that are displayed on the printer's LCD screen.

Today I distracted myself a bit and spent some time reverse-engineering the spool format and printer protocol used by the Sony UP-DR150. I committed the initial cut at a backend, and if it turns out to work, I'll go ahead and add that to gutenprint as well.

I find myself wondering if I should just unify all of those disparate backends into a single 'gutenprint-usb' backend that handles everything.
I'm already up to five backends, and that number will only grow.

While all the backends basically do the same thing, there isn't very much directly common code, and trying to genericize the almost-but-not-quite common bits will make things much more complex without really buying us anything. That said, presenting the system with a single executable may be the right way going forward.

The Sony UP-DR200 and DNP DS40 may soon gain improved support as well.

In other news, I had a report of a crash with the CW1200 driver when trying to use Monitor mode. Unfortunately in the process of moving I seem to have lost all of my serial cables -- so I can't get a console on my development board and recreate the crash in a full debug-enabled environment.

I need to do someting about this ASAP.

Syndicated 2013-07-14 21:19:57 from Solomon Peachy

cw1200 driver is officially mainlined

As of about eighteen hours ago, the ST-E CW1100/CW1200 WLAN device driver was merged into the Linus's mainline linux tree, culminating more than a yearlong effort to get the driver into shape.

I'm now trying to get official permission to have the necessary firmware included in the linux-firmware tree. This is stymied by ST-E's recent implosion and the fleeing of all of my former contacts, but I'm told the WLAN group will live on, most likely under the STMicro name.

There's also the open question of support for the CW1x50 and CW1x60 successor chips. I need access to hardware to do any meaningful development, and I have no idea where to obtain that.

Ah, it's a good day.

Syndicated 2013-07-10 13:51:08 from Solomon Peachy

Photo printer developments

Today, I picked up a 20 kilogram package from FedEx. Upon opening the more-than-a-litte-abused box, buried in the sea of foam peanuts was a tightly-bubble-wrapped bundle of high-end kiosk-scale photo printer -- A Sinfonia (nee Shinko) CHC-S2145.

It was express-shipped to me by LiveLink Technology, a photo kiosk solution provider based out of Merry Old England, for the express purpose of getting it to work with Linux (by means of Gutenprint). LiveLink bucks the industry trend by using Linux under the hood wherever possible, so by sponsoring this work they benefit through lower costs and greatly improved flexibility, and the community benefits from the native support of a truly professional printer.

The Sinfonia CHC-S2145 carries enough media to handle seven hundred prints at a time, spits out a 4x6" print in seven seconds, and will do so day in and day out. As a testament to their robustness, this one came heavily broken in to the tune of nearly 78,000 prints.

Anyway. I've already committed the initial support to Gutenprint, which now generates proper raw spool files that match the output of the Windows drivers. Unfortunately (as I've come to expect) this printer requires an intelligent, two-way backend, which will take a bit more time to put together. Fortunately I'll able to reuse large chunks of the backend code I've written for other dye-sublimation printers.

In other news, earlier this holiday weekend I polished most of the rough edges off of the Kodak 1400/805 Gutenprint code, and should have another '805 in a few days -- the seller agreed to send a replacement after the first one aggressively blew the magic smoke out of its power supply.

It's been a productive few days. But now it's time to produce some sleep.

Syndicated 2013-07-06 03:16:41 from Solomon Peachy