From: Athanasios A. <th...@at...> - 2005-06-01 09:09:15
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Hello Craig Thank you for replying... >> 2. How similar is the cfstix with pcmcia? I always thought that CF >> is a memory type and that the bus it operates upon is in a way >> tailored to the CF controller...However, gumstix uses it in a way >> more like a generalised bus. In terms of accessing it from the >> linux kernel, what is it regarded as? Is it closer to PCMCIA or >> does it have some dedicated driver? > > >CF is PCMCIA on the bus, just with a different physical form factor >for both connector and cards. From the kernel's point of view, it >uses the pcmcia stuff to access the cards. I am glad this was made clear. >> 3.Does the menuconfig resolves conflicts between modules that get >> compiled within the kernel? For example, i am planning to build two >> different images of the kernel. One for use with the stuart and >> cfstix and one for use with the stuart and audiostix...I am >> planning to do this in the future for any combination of devices i >> might acquire. Therefore depending on the application i want to >> develop the kernel will be loaded with only the necessary code...So >> if i attempt to remove a module that is needed from another module >> will i get notified? > > >menuconfig doesn't resolve everything. For example, the MMC driver >and the PCMCIA driver use some of the same resources on the PXA cpu, >but need to configure them differently -- so you can't have both >PCMCIA and MMC drivers working at the same time. Well, you cant anyway with the present gamut of gumstix products (i think). Only basix has MMC, but basix does not have the 92 pin connector so no cfstix and no possibility of conflict. >The kernel doesn't >currently prevent two drivers from acquiring some of the shared >resources on the PXA (like GPIO lines) though it looks like work is >being done in that direction on the linux-arm mailing list (or was a >while back, I haven't checked the threads recently). I had been >planning on doing some kind of GPIO acquire/release mechanism to >prevent drivers from stepping on each other at runtime, but when I >noticed that someone else on the arm-linux list seemed to be doing >the same thing (only more ambitious than what I had planned), I >decided to just wait and use that. I've been away from buildroot/ >kernel stuff for a while, working on some of our backend systems >here, but plan to return there soon, at which point there's a long >list of stuff I want to get in, including this. You lost me there. Maybe i am going to far with this but is not the cfstix (well, basically its controler) on a Data and Address Bus? Do you use the GPIO lines for control signals or data transfer? >> 5. Regarding an LCD module...For the project i have in mind, i dont >> need to show a lot of things to the user, so i was thinking about >> acquiring one of these small cheap serial LCD modules and interface >> it to one of the serial ports of the gumstix. However, i noticed in >> the mailing list the work of "Holly Gates" with LCDs and as far as >> i can see "she" is not witting any "custom" code to drive that >> LCD...In a way it is all being taken care of, by the kernel...How >> is this possible? Is the memory used for terminal output being >> mapped to a special range where it gets transferred to the LCD? > > >"She" is a "he" :) Yes, the PXA has a frambuffer device in the >kernel tree, which is basically just an area of memory that gets >mapped to the LCD controller. The kernel takes care of the details >once you've set things up by initializing the controller for your >panel's characteristics. Yes i assumed that...It was hard to imagine a woman with such a keen interest on the gumstix (no offense for the gumstix ofcourse)... :-) So from what you are saying, a serial LCD is out of the question and i would have to go on and write the code to drive it (With the negative side that terminal output wont be channeled to the LCD.). This controller you are talking about, is it a module an app or hardware? >> 6. On the same topic...As far as i know, the only way to go >> graphical in linux is to run an X server and then send commands to >> it. In DOS one could use INT 10 and pass to graphical mode and then >> write to the VGA memory almost directly depending on the mode the >> VGA was entered. I suppose this is not possible to be done in linux >> (except with some special tricks perhaps? :-) )....So is it safe to >> assume that this graphical penguin that Holly Gates is showing at >> "her" posts is rendered through calls to the X server compiled for >> gumstix? > > >Not sure what Holly is doing, but you can write directly to the >framebuffer in linux w/out using X (this is in fact what X does -- >write directly to the framebuffer). So from what you are saying, even text mode is implemented by writting to the framebuffer memory. > There are also graphics- >primitive libraries out there which you can basically invoke >draw_circle(x,y,r) and such, and they'll do the underlying write-to- >framebuffer for you. Dont i have to "pass to a sort of graphics mode" before i do that? >http://www.google.com/ :) Yes...I know...Too high an information SNR though ;-) Many thanks again. thanOS |
From: Holly G. <hgates@EINK.com> - 2005-06-01 13:52:59
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> >> 5. Regarding an LCD module...For the project i have in mind, i dont > >> need to show a lot of things to the user, so i was thinking about > >> acquiring one of these small cheap serial LCD modules and interface > >> it to one of the serial ports of the gumstix. However, i noticed in > >> the mailing list the work of "Holly Gates" with LCDs and as far as > >> i can see "she" is not witting any "custom" code to drive that > >> LCD...In a way it is all being taken care of, by the kernel...How > >> is this possible? Is the memory used for terminal output being > >> mapped to a special range where it gets transferred to the LCD? > > >"She" is a "he" :) Yes, the PXA has a frambuffer device in the > >kernel tree, which is basically just an area of memory that gets > >mapped to the LCD controller. The kernel takes care of the details > >once you've set things up by initializing the controller for your > >panel's characteristics. > > Yes i assumed that...It was hard to imagine a woman with such a keen > interest on the gumstix (no offense for the gumstix ofcourse)... :-) > I think there are some actual women on this list, although I should know better than anyone that it is hard to tell from a name! A while ago there was a huge debate in the comments under a slashdot story about whether I was a female or not. Lots of nerds were getting pretty excited about asking me out on a date, until it eventually was discovered to much chagrin that I was just an ordinary man-nerd. > So from what you are saying, a serial LCD is out of the question and i > would have to go on and write the code to drive it (With the negative > side that terminal output wont be channeled to the LCD.). This > controller you are talking about, is it a module an app or hardware? > You could still use a serial LCD if you wanted to, but of course it would take up a serial port and you couldn't show graphics on it. The graphics LCD hooks up directly to the pxa chip, and uses a hardware LCD controller subsystem within the pxa. The kernel interfaces to this subsystem though a couple registers, and the framebuffer. I believe you can actually cause the console messages and terminal to output to the framebuffer. I've not done that so I'm not sure how to set it up, but its probably not that hard. I seem to recall that there might be a checkbox for it in the kernel menuconfig... That being said, the hardware interface for a simple 2 line x 16 character LCD is going to be way easier for you to do than to hook up a graphical LCD. Its not that bad if you have some hardware hacking skills, but if you are not handy with the soldering iron and small wires (or PCB layout software), it is going to be tough for you. You can see the order of magnitude of the task difficulty by looking at the photos of my little LCD effort on the wiki. Hooking up a serial port and power is much more simple. > >> 6. On the same topic...As far as i know, the only way to go > >> graphical in linux is to run an X server and then send commands to > >> it. In DOS one could use INT 10 and pass to graphical mode and then > >> write to the VGA memory almost directly depending on the mode the > >> VGA was entered. I suppose this is not possible to be done in linux > >> (except with some special tricks perhaps? :-) )....So is it safe to > >> assume that this graphical penguin that Holly Gates is showing at > >> "her" posts is rendered through calls to the X server compiled for > >> gumstix? > > > > > > >Not sure what Holly is doing, but you can write directly to the > >framebuffer in linux w/out using X (this is in fact what X does -- > >write directly to the framebuffer). > So from what you are saying, even text mode is implemented by writting > to the framebuffer memory. > > > There are also graphics- > >primitive libraries out there which you can basically invoke > >draw_circle(x,y,r) and such, and they'll do the underlying write-to- > >framebuffer for you. > Dont i have to "pass to a sort of graphics mode" before i do that? > I am just opening /dev/fb0 and writing stuff to it, usually read from a bitmap image file. Its very easy, and you can look at my source code on the wiki. There are some image viewers and web browers that can write directly to the framebuffer too, although I have not used them on the pxa. There is also some graphics libraries which can help you draw circles, etc. as Craig says, but I'm not familiar with how to use them. > >http://www.google.com/ :) > > Yes...I know...Too high an information SNR though ;-) > Look for "framebuffer linux library" -Holly |
From: Victor M. <Vic...@no...> - 2005-06-01 20:07:04
|
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From: Athanasios A. <th...@at...> - 2005-06-02 11:09:50
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Hello Holly Many thanks for replying... >I think there are some actual women on this list, although I should know >better than anyone that it is hard to tell from a name! A while ago >there was a huge debate in the comments under a slashdot story about >whether I was a female or not. Lots of nerds were getting pretty excited >about asking me out on a date, until it eventually was discovered to >much chagrin that I was just an ordinary man-nerd. Yes, but probably these actual women are not frequent readers of the list... Anyway, i suspect the gumstix mailing list would be the last place to look for a date...Even for people like us (nerds is it?) :-) >That being said, the hardware interface for a simple 2 line x 16 >character LCD is going to be way easier for you to do than to hook up a >graphical LCD. Its not that bad if you have some hardware hacking >skills, but if you are not handy with the soldering iron and small wires >(or PCB layout software), it is going to be tough for you. You can see >the order of magnitude of the task difficulty by looking at the photos >of my little LCD effort on the wiki. Hooking up a serial port and power >is much more simple. I think the functionality is worth the trouble.Anyway, i have a serial interface LCD in mind which can do graphics but i suspect the refresh rate (trying to show a "real time" waveform) will be low...Thats this http://www.seetron.com/bgx128_1.htm and this one http://www.melabs.com/products/SGX120L.htm >I am just opening /dev/fb0 and writing stuff to it, usually read from a >bitmap image file. Its very easy, and you can look at my source code on >the wiki. There are some image viewers and web browers that can write >directly to the framebuffer too, although I have not used them on the >pxa. There is also some graphics libraries which can help you draw >circles, etc. as Craig says, but I'm not familiar with how to use them. . . >Look for "framebuffer linux library" I really got back some very interesting results from that query, thank you very much. I will have a look at your code as well as i am qurious to see how you pass to graphics mode (i suspect you dont call fbset from within your code) Many Thanks. thanOS |
From: Holly G. <hgates@EINK.com> - 2005-06-02 13:09:45
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> >I am just opening /dev/fb0 and writing stuff to it, usually read from a > >bitmap image file. Its very easy, and you can look at my source code on > >the wiki. There are some image viewers and web browers that can write > >directly to the framebuffer too, although I have not used them on the > >pxa. There is also some graphics libraries which can help you draw > >circles, etc. as Craig says, but I'm not familiar with how to use them. > . > . > >Look for "framebuffer linux library" > > I really got back some very interesting results from that query, thank > you very much. > I will have a look at your code as well as i am qurious to see how you > pass to graphics mode (i suspect you dont call fbset from > > within your code) > Indeed I do not call fbset. I set up the framebuffer size at boot time by passing an argument on the linux command line through uboot. Then I use a shell script post bootup to tweak some of the timing registers for the LCD controller. You should be able to do that from the command line too, but I never spent much time figuring it out. Fortunately Baskar did some more work on that and you can see the results at the bottom of the Display wiki page. You don't really need to "pass to graphics mode". Once you boot up the display is scanned continuously with the contents of /dev/fb0. If you drop some new stuff it /dev/fb0, then it shows up on the screen. There is a LCD enable bit in the LCD control registers, but when I've tried turning it off I have never gotten the display re-enabled again without rebooting. -Holly > Many Thanks. > thanOS > |