serial-text

Background and instructions for typekey, etc.

Registered by Loye Young on 2008-10-14

Correspondence between the maintainer and author of typekeys, a program supplied by serial-text.

Blueprint information

Status:: Not started

Approver:: Loye Young

Priority:: Undefined

Drafter:: Loye Young

Direction:: Needs approval

Assignee:: None

Definition:: Approved

Series goal:: None

Implementation:: Unknown

Milestone target:: None

Related branches

lp:serial-text

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Loye Young
<loye.young [at some email domain] like iycc.net>
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Re: serial barcode reader in linux 
8 messages
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Jiri Bohac
<jbohac [at some email domain] like suse >

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Mon, Jun 4, 2007 at 12:42 PM

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loye.young [at some email domain] like iycc.net
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Hi, 
 
> This is a very interesting and apparently elegant approach. I 
> apologize for my technical ignorance, however. I don't 
> understand how to make typekeys work. 
> 
> 1.  How is this program to be compiled? As a kernel module? A 
> device driver? 
 
It is a standard userspace program. Modern 2.6 kernels allow 
userspace programs to inject iput events into the kernel using 
the uinput device (/dev/input/uinput) 
 
You just compile it with 
 
gcc -o typekeys typekeys.c 
 
This produces a typekeys executable. 
 
> 2.  You say: 
> 
>  * Translates data from stdin to uinput key press / key release 
>  * sequences and feeds them to /dev/input/uinput 
> 
> How does the data get to stdin in the first place? What's 
> reading the serial port? 
> 
> 3.  What is the ttySA device and how does it get created? 
> There's not one on my (Debian/Ubuntu) systems. Is it the SUSE 
> name for ttyS0? 
 
oops, that was a typo. It was meant to be ttyS0. 
I've seen in one of your posts (don't remember where), that wwhen 
you do "cat /dev/ttyS0", you can see the data coming from the 
barcode reader. 
 
So this program can read the data the same way cat does. 
You can redirect the stdin, or cat the data into it. 
 
cat /dev/ttyS0 | typekeys typekeys.conf 
or 
typekeys typekeys.conf < /dev/ttyS0 
 
You need to have the serial port set up properly (using stty). 
But once you can get the correct data using cat, typekeys should 
work. 
 
 
> 4.  Do I need to put it in the rcS script so that it will 
> invoke on bootup? 
 
yes, you need to somehow ensure this program will run. My 
suggestion would be putting it in /etc/inittab 
But as you probably (?) can not redirect IO in inittab, I would 
first make a script (e.g. /usr/local/bin/barcode) 
with something like: 
#!/bin/bash 
stty /dev/ttyS0 whatever parameters you need 
/usr/local/bin/typekeys < /dev/ttyS0 
 
And then run this from the inittab (e.g. below the stty lines): 
tk:2345:respawn:/usr/local/bin/barcode 
 
Or put it somewhere in rcS, you just need to make sure it does 
not get killed when the parent process terminates (you may use 
something like nohup for that) 
 
> 5.  Once typekeys is invoked, does the barcode data show up in 
> all applications, including applications running under X, just 
> like the keyboard? 
 
exactly. 
 
j. 

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Loye Young
<loye.young [at some email domain] like iycc.net>

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Mon, Jun 4, 2007 at 4:19 PM

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To:
Jiri Bohac <jbohac [at some email domain] like suse >, Vojtech Pavlik <vpavlik [at some email domain] like suse >
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Biggest issue I see is how to make sure the device gets handled correctly by udev, because ttyS0 might change from reboot to reboot. Vojtech Pavlik (<a href="mailto:vpavlik [at some email domain] like suse " target="_blank">vpavlik [at some email domain] like suse </a>) has written very similar drivers for serial keyboards and they are incorporated in the kernel now. (See the kernel keyboard input source tree, ./linux/drivers/input/keyboards, especially
xtkbd.c, sunkbd.c, lkkdbd.c, hilkbd.c, and atkbd.c.) Your code looks like a simplified version of those. The uinput solution in this case seems like a circumvention of the udev approach to device management. It seems to me that a driver in the input/keyboards branch of the kernel tree would be the right solution.
 I note that you both have [at some email domain]<a href="http://suse.cz" target="_blank">suse.cz</a> email addresses, so perhaps you are acquainted with Mr. Pavlik. He single-handedly wrote the input device drivers in the kernel, so he's been down this road before. Does he have any insight on this?
 Loye Young -- Loye Young Isaac & Young Computer Company Laredo, Texas (956) 857-1172 <a href="mailto:loye.young [at some email domain] like iycc.net" target="_blank">loye.young [at some email domain] like iycc.net</a><div style='padding:5 0'>[Quoted text hidden]</div>Jiri Bohac <<a href="mailto:jbohac [at some email domain] like suse " target="_blank">
jbohac [at some email domain] like suse </a>> wrote:<blockquote style="border-left:2px solid rgb(16, 16, 255);margin-left:5px;padding-left:5px">
Hi, I saw your posts in many places, trying to find a way to connect your serial barcode reader to linux and make it transparently available to applications as a keyboard. Don't know if you found a solution yet. I will need the same
 thing sooner or later, so I made a small program called "typekeys" that you might find useful. You can get it here <a href="http://www.jikos.cz/~jbohac/goodies/" target="_blank">http://www.jikos.cz/~jbohac/goodies/
</a> You can then use like this: typekeys typekeys.conf You need to have uinput working (modprobe uinput). Hope you can use it. Good luck. -- Jiri Bohac SUSE Labs, SUSE CZ
 </blockquote> 

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Mail Delivery System
<MAILER-DAEMON [at some email domain] like suse >

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Mon, Jun 4, 2007 at 4:20 PM

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To:
loye.young [at some email domain] like iycc.net
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This is the Postfix program at host <a href="http://spicebloom.suse.cz" target="_blank">spicebloom.suse.cz</a>. 
 
I'm sorry to have to inform you that your message could not be 
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For further assistance, please send mail to <postmaster> 
 
If you do so, please include this problem report. You can 
delete your own text from the attached returned message. 
 
                       The Postfix program 
 
<<a href="mailto:vpavlik [at some email domain] like suse ">vpavlik [at some email domain] like suse </a>>: host 
   /data/cyrus/lib/imap/socket/lmtp[/data/cyrus/lib/imap/socket/lmtp] said: 
   550-Mailbox unknown.  Either there is no mailbox associated with this 
   550-name or you do not have authorization to see it. 550 5.1.1 User unknown 
   (in reply to RCPT TO command) 
 Final-Recipient: rfc822; <a href="mailto:vpavlik [at some email domain] like suse ">vpavlik [at some email domain] like suse </a> 
Action: failed 
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Diagnostic-Code: X-Postfix; host 
   /data/cyrus/lib/imap/socket/lmtp[/data/cyrus/lib/imap/socket/lmtp] said: 
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 ---------- Forwarded message ---------- From: "Loye Young" <loye.young [at some email domain] like iycc.net> To: "Jiri Bohac" <jbohac [at some email domain] like suse >, "Vojtech Pavlik" <vpavlik [at some email domain] like suse > Date: Mon, 4 Jun 2007 16:19:53 -0500 Subject: Re: serial barcode reader in linux Biggest issue I see is how to make sure the device gets handled correctly by udev, because ttyS0 might change from reboot to reboot. Vojtech Pavlik (<a href="mailto:vpavlik [at some email domain] like suse " target="_blank">vpavlik [at some email domain] like suse </a>) has written very similar drivers for serial keyboards and they are incorporated in the kernel now. (See the kernel keyboard input source tree, ./linux/drivers/input/keyboards, especially
xtkbd.c, sunkbd.c, lkkdbd.c, hilkbd.c, and atkbd.c.) Your code looks like a simplified version of those. The uinput solution in this case seems like a circumvention of the udev approach to device management. It seems to me that a driver in the input/keyboards branch of the kernel tree would be the right solution.
 I note that you both have [at some email domain]<a href="http://suse.cz" target="_blank">suse.cz</a> email addresses, so perhaps you are acquainted with Mr. Pavlik. He single-handedly wrote the input device drivers in the kernel, so he's been down this road before. Does he have any insight on this?
 Loye Young -- Loye Young Isaac & Young Computer Company Laredo, Texas (956) 857-1172 <a href="mailto:loye.young [at some email domain] like iycc.net" target="_blank">loye.young [at some email domain] like iycc.net</a> 
 <div>On 6/4/07, Jiri Bohac <<a href="mailto:jbohac [at some email domain] like suse " target="_blank">jbohac [at some email domain] like suse </a>> wrote:<blockquote class="gmail_quote" style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">
Hi, > This is a very interesting and apparently elegant approach. I > apologize for my technical ignorance, however. I don't > understand how to make typekeys work. > > 1. How is this program to be compiled? As a kernel module? A
 > device driver? It is a standard userspace program. Modern 2.6 kernels allow userspace programs to inject iput events into the kernel using the uinput device (/dev/input/uinput) You just compile it with
 gcc -o typekeys typekeys.c This produces a typekeys executable. > 2. You say: > > * Translates data from stdin to uinput key press / key release > * sequences and feeds them to /dev/input/uinput
 > > How does the data get to stdin in the first place? What's > reading the serial port? > > 3. What is the ttySA device and how does it get created? > There's not one on my (Debian/Ubuntu) systems. Is it the SUSE
 > name for ttyS0? oops, that was a typo. It was meant to be ttyS0. I've seen in one of your posts (don't remember where), that wwhen you do "cat /dev/ttyS0", you can see the data coming from the
 barcode reader. So this program can read the data the same way cat does. You can redirect the stdin, or cat the data into it. cat /dev/ttyS0 | typekeys typekeys.conf or typekeys typekeys.conf < /dev/ttyS0
 You need to have the serial port set up properly (using stty). But once you can get the correct data using cat, typekeys should work. > 4. Do I need to put it in the rcS script so that it will
 > invoke on bootup? yes, you need to somehow ensure this program will run. My suggestion would be putting it in /etc/inittab But as you probably (?) can not redirect IO in inittab, I would first make a script (
e.g. /usr/local/bin/barcode) with something like: #!/bin/bash stty /dev/ttyS0 whatever parameters you need /usr/local/bin/typekeys < /dev/ttyS0 And then run this from the inittab (e.g. below the stty lines):
 tk:2345:respawn:/usr/local/bin/barcode Or put it somewhere in rcS, you just need to make sure it does not get killed when the parent process terminates (you may use something like nohup for that) > 5. Once typekeys is invoked, does the barcode data show up in
 > all applications, including applications running under X, just > like the keyboard? exactly. j. </blockquote></div> Jiri Bohac <<a href="mailto:jbohac [at some email domain] like suse " target="_blank">
jbohac [at some email domain] like suse </a>> wrote:<blockquote style="border-left:2px solid rgb(16, 16, 255);margin-left:5px;padding-left:5px">
Hi, I saw your posts in many places, trying to find a way to connect your serial barcode reader to linux and make it transparently available to applications as a keyboard. Don't know if you found a solution yet. I will need the same
 thing sooner or later, so I made a small program called "typekeys" that you might find useful. You can get it here <a href="http://www.jikos.cz/~jbohac/goodies/" target="_blank">http://www.jikos.cz/~jbohac/goodies/
</a> You can then use like this: typekeys typekeys.conf You need to have uinput working (modprobe uinput). Hope you can use it. Good luck. -- Jiri Bohac SUSE Labs, SUSE CZ
 </blockquote> 
 
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Loye Young
<loye.young [at some email domain] like iycc.net>

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Mon, Jun 4, 2007 at 4:22 PM

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To:
Vojtech Pavlik <vojtech [at some email domain] like suse >
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Cc:
Jiri Bohac <jbohac [at some email domain] like suse >
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Jiri Bohac
<jbohac [at some email domain] like suse >

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Mon, Jun 4, 2007 at 5:06 PM

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To:
Loye Young <loye.young [at some email domain] like iycc.net>
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Cc:
Jiri Bohac <jbohac [at some email domain] like suse >, Vojtech Pavlik <vpavlik [at some email domain] like suse >
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Hi, 
 
> Biggest issue I see is how to make sure the device gets handled correctly by 
> udev, because ttyS0 might change from reboot to reboot. 
 
Probably not for standard machines with a single serial 
contoller. This might be an issue with e.g. multiple PCI serial 
controllers, but on standard setups, ttyS0 should stay ttyS0 
AFAIK. 
 
> Vojtech Pavlik (<a href="mailto:vpavlik [at some email domain] like suse ">vpavlik [at some email domain] like suse </a>) has written very similar drivers for serial 
> keyboards and they are incorporated in the kernel now. (See the kernel 
> keyboard input source tree, ./linux/drivers/input/keyboards, especially 
> xtkbd.c, sunkbd.c, lkkdbd.c, hilkbd.c, and atkbd.c.) Your code looks like a 
> simplified version of those. The uinput solution in this case seems like a 
> circumvention of the udev approach to device management. 
 
Well, yes, the code is a quick hack and could be useful right 
now. I don't think it circumvents anything. It just takes the easy 
approach and uses the uinput interface which is already present 
in the kernel. 
 
Personally, I don't see real benefints of having simple drivers 
like this in the kernel - it just works in userspace, it's easier 
to tweak and improve. It can be rewritten/extended in any 
language (perl?). 
 
I'll talk to people at work who work on input drivers whether 
they would like something like this as a kernel driver. 
 
j. 
 
-- 
Jiri Bohac <<a href="mailto:jbohac [at some email domain] like suse ">jbohac [at some email domain] like suse </a>> 
SUSE Labs, SUSE CZ 
 

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Loye Young
<loye.young [at some email domain] like iycc.net>

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Mon, Jun 4, 2007 at 7:41 PM

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To:
Jiri Bohac <jbohac [at some email domain] like suse >
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" the code is a quick hack and could be useful right now." Good point. As the King of the Penguins has said, "The perfect is often the enemy of the good." "uses the uinput interface which is already present in the kernel."
 "Personally, I don't see real benefints of having simple drivers like this in the kernel - it just works in userspace, it's easier to tweak and improve. It can be rewritten/extended in any language (perl?)."
 I need to do some reading up on uinput and its interrelation to udev. If I'm not mistaken, Greg K-H and your colleagues [at some email domain]<a href="http://suse.cz" target="_blank">suse.cz</a> rewrote the current input system around udev to do what you suggest: pull drivers out of the kernel and put them into userspace. Although I understand the concept, I don't understand the code enough to know exactly how they work.
 "I'll talk to people at work who work on input drivers whether they would like something like this as a kernel driver." Whatever the solution, it should be distributed as part of the stock GNU/Linux stack, IMHO. I have gotten lots of email from folks who have the same problem, but so far no one has come up with a solution that "just works". Yours is the closest by far. The concept of plugging into what's already written is implicit in uinput, evdev, and udev. Your solution is the only one that tries to play by the rules.
 Let me know what you and the input guys come up with. I've got a running list of folks who are wanting to know how to make this work. I've been searching for a solution for well over two years now. 
(Oh, and pardon my Texas syntax. The Bushes aren't the only Texans who mangle English.) Loye Young<div style='padding:5 0'>[Quoted text hidden]</div><div style='padding:5 0'>[Quoted text hidden]</div>
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Jiri Bohac
<jbohac [at some email domain] like suse >

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Tue, Jun 5, 2007 at 4:01 AM

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Loye Young <loye.young [at some email domain] like iycc.net>
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Hi, 
> "uses the uinput interface which is already present in the kernel." 
> "Personally, I don't see real benefints of having simple drivers 
> like this in the kernel - it just works in userspace, it's easier 
> to tweak and improve. It can be rewritten/extended in any 
> language (perl?)." 
> 
> I need to do some reading up on uinput and its interrelation to udev. If I'm 
> not mistaken, Greg K-H and your colleagues [at some email domain]<a href="http://suse.cz" target="_blank">suse.cz</a> rewrote the current 
> input system around udev to do what you suggest: pull drivers out of the 
> kernel and put them into userspace. Although I understand the concept, I 
> don't understand the code enough to know exactly how they work. 
 
I don't think you don't quite understand what udev does. 
Besically, udev is there to populate /dev with device files. 
That's its primary purpose and that's what it does form 90% of 
devices: it merely creates the device files in /dev on 
boot/hotplug. It gets /dev very close to the state it was 
before, when all the device files were created there statically 
by the distribution. 
 
In some cases, it does a little magic. Like ensuring persistent 
network device names, so no matter what network cards you take 
out or add into your computer, the ones that stay will keep their 
names. Similar thing can be done for disks. Need for this emerged 
as the kernel started to probe devices asynchronously, so that 
the order in which they are discovered and drivers loaded may 
change from boot to boot. Udev is there to handle the result as 
consistently as possible. 
 
But udev is by no means a device driver for anything. Really it 
just creates appropriate device files in /dev and assigns network 
interface names. Not much else. So don't be afraid of it. 
 
> "I'll talk to people at work who work on input drivers whether 
> they would like something like this as a kernel driver." 
 
I just talked to our new input expert (Vojtech is not doing that 
so much anymore), and said he would have done it exactly the way 
I have. I.e. a userspace program feeding the keypresses into 
/dev/input/uinput. There are many different serial devices and it 
is much easier adapting a userspace program for a particular 
device than having to adapt it in the kernel and having to 
recompile it just because of that. 
 
The reason some serial keyboard drivers are in the kernel already 
is that the drivers existed before uinput existed, so it was the 
only way to do that. They could easily be taken out of the kernel 
and replaced by a userspace program, but it would just make life 
mor difficult for people who set their keyboards up already using 
the kernel driver. 
 
> Whatever the solution, it should be distributed as part of the stock 
> GNU/Linux stack, IMHO. 
 
Well, that's just a matter of packaging it for whatever 
distribution you use and pushing it into the distribution. 
I might do that for SUSE one day, but hey, it's so trivial it 
might not be even worth doing it ;-) 
It's good enough for barcode/rfid readers, but maybe not for a 
all serial keyboards out there. It would probably be needed to 
allow some conditional statements in the config file or something 
like that. Not all devices have context-less output - one byte of 
output may mean different things depending on the bytes following 
or preceeding. My program can not handle that. So maybe one day 
someone will write something more generic and more usefult, worth 
pushing to all the distributions out there. 
 
> (Oh, and pardon my Texas syntax. The Bushes aren't the only Texans who 
> mangle English.) 
 
Hmm, not only do the Bushes mangle English, but they also cause 
havoc Prague's traffic ;-) We happen to have G. W. B. visiting 
_today_ and half of the city is closed because of that ;-))) 
 
 
 
-- 
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Jiri Bohac
<jbohac [at some email domain] like suse >

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Wed, Aug 8, 2007 at 9:12 AM

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Loye Young <loye.young [at some email domain] like iycc.net>
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Hi Loye, 
 
> Although I am no longer in need of the scanner, it seems that there is a lot 
> of interest in the subject. In order to hand over the reins, I have 
> registered a project in Launchpad (<a href="http://launchpad.net" target="_blank">http://launchpad.net</a>) 
> called "serial-text". Please sign up at Launchpad and contribute. 
> 
> With your permission, I would like to post the correspondence between you and 
> I, along with your code. Please advise what license you would like the 
> package to have. If you would like to take over maintenance of the project, I 
> would be toe-tapping happy about that, because I am not the right person for 
> the job. However, if you are unable to take over, I will oversee the project 
> until it gets on its feet independently. 
 
Sure, you can do anything with the code and you can post the 
correspondence anywhere. 
 
The code (and the config file are available from: 
<a href="http://www.jikos.cz/~jbohac/goodies/typekeys.c" target="_blank">http://www.jikos.cz/~jbohac/goodies/typekeys.c</a> 
and 
<a href="http://www.jikos.cz/~jbohac/goodies/typekeys.conf" target="_blank">http://www.jikos.cz/~jbohac/goodies/typekeys.conf</a> 
 
As you've seen already, it's really simple. The license is "GPL2 
or newer". Althought it can be useful as is, it is leiterallily a 
couple of lines of code (except the key table copied from 
somewhere else), so anyone who will want to extend it may well 
prefer to start from scratch. 
 
 
Regards, 
<div style='padding:5 0'>[Quoted text hidden]</div>
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