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Hello, gentlemen, I am experiencing something that does not make sense to me. To make my debugging easier I wish to use the printf function to send formatted output to UARTO. Fine. As far as I can see, I did everything right: I rewrote the putchar function so it writes to UART0, and the putchar function works OK. However, when I use the printf function, it does not output to UART0 (if it outputs to something at all), and I can't understand why not. Checking the .MAP file, I see the compiler takes the putchar function that is in my main.o and the remaining functions that printf uses (such as puts, fflush, etc) it takes from libc.a . If I DO NOT write my putchar, I see from the .MAP file that the compiler takes putchar.o from libc.a -- and then I understand why it wouldn't send anything to the UART0. But why doesn't printf send to the UART0 if my putchar function tells it to? Hoping for some enlightening from you gurus, Fernando |
can't get printf() to print on UART0 with GNU
Started by ●February 24, 2005
Reply by ●February 24, 20052005-02-24
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--- In , "tiogate" <gate@t...> wrote: > > Hello, gentlemen, > > I am experiencing something that does not make sense to me. To > make my debugging easier I wish to use the printf function to send > formatted output to UARTO. > > Fine. As far as I can see, I did everything right: I rewrote the > putchar function so it writes to UART0, and the putchar function > works OK. > > However, when I use the printf function, it does not output to > UART0 (if it outputs to something at all), and I can't understand > why not. > > Checking the .MAP file, I see the compiler takes the putchar > function that is in my main.o and the remaining functions that > printf uses (such as puts, fflush, etc) it takes from libc.a . > > If I DO NOT write my putchar, I see from the .MAP file that the > compiler takes putchar.o from libc.a -- and then I understand why it > wouldn't send anything to the UART0. But why doesn't printf send to > the UART0 if my putchar function tells it to? > > Hoping for some enlightening from you gurus, > > Fernando All depends on what c library you are using, with newlib you need to override _write or _write_r (reentrant version) eg. int _write_r(void *reent, int fd, char *ptr, size_t len) { // send data via uart UART_DataSend( UART0, ptr, len ); return len; } unlike other c libs newlib does not use putchar. Look in the newlib docs for other system overdides. Regards Spen |
Reply by ●February 24, 20052005-02-24
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On 24 Feb 2005 at 15:19, tiogate wrote: > > > Hello, gentlemen, > > I am experiencing something that does not make sense to me. To make > my debugging easier I wish to use the printf function to send > formatted output to UARTO. > > Fine. As far as I can see, I did everything right: I rewrote the > putchar function so it writes to UART0, and the putchar function works > OK. > > However, when I use the printf function, it does not output to > UART0 (if it outputs to something at all), and I can't understand why > not. > > Checking the .MAP file, I see the compiler takes the putchar > function that is in my main.o and the remaining functions that > printf uses (such as puts, fflush, etc) it takes from libc.a . > > If I DO NOT write my putchar, I see from the .MAP file that the > compiler takes putchar.o from libc.a -- and then I understand why it > wouldn't send anything to the UART0. But why doesn't printf send to > the UART0 if my putchar function tells it to? > > Hoping for some enlightening from you gurus, > If you are using the gcc toolset, then you are probably using newlib. Hence you need to port newlib to your specific hardware. Look for "Porting Newlib" and you should find a fair amount of info. There is such a porting library for the LPC. You can download it at http://www.aeolusdevelopment.com/Articles/download.html. There are some issues when using the interrupt uart routines in this package. ( The assembler portion is not linked in from the library) Regards Anton Erasmus-- A J Erasmus |
Reply by ●February 24, 20052005-02-24
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--- In , "ntfreak2000" <ntfreak2@h...> wrote: >> > All depends on what c library you are using, with newlib you need to > override _write or _write_r (reentrant version) eg. > > Spen I am not sure, but I think I am not using newlib. The hint is: there is no reent.h available. The package I installed was GCCARM331 downloaded from Keil Evaluation (http://www.keil.com/demo/evaldl.asp). The Manuals mention "GNUPro Tools" and there is not one occurrence of the word "newlib" in them. Does anybody know what libs are these, and which function(s) I should override? Fernando |
Reply by ●February 24, 20052005-02-24
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On 24 Feb 2005 at 18:52, tiogate wrote: > > > --- In , "ntfreak2000" <ntfreak2@h...> wrote: > >> > All depends on what c library you are using, with newlib you > need to > override _write or _write_r (reentrant version) eg. > > Spen > > I am not sure, but I think I am not using newlib. The hint is: there > is no reent.h available. The package I installed was GCCARM331 > downloaded from Keil Evaluation (http://www.keil.com/demo/evaldl.asp). > The Manuals mention "GNUPro Tools" and there is not one occurrence of > the word "newlib" in them. > > Does anybody know what libs are these, and which function(s) I > should override? > The best is probably to ask Keil. The want you to later buy their full version, so it is in their interest to help you. If they do not help you switch to the tools on http://www.gnuarm.com which uses newlib. Regards Anton Erasmus -- A J Erasmus |
Reply by ●February 24, 20052005-02-24
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At 07:03 PM 2/24/05 +0200, Anton Erasmus wrote: >If you are using the gcc toolset, then you are probably using newlib. Hence >you need to port newlib to your specific hardware. Look for "Porting >Newlib" and >you should find a fair amount of info. There is such a porting library for >the LPC. >You can download it at >http://www.aeolusdevelopment.com/Articles/download.html. >There are some issues when using the interrupt uart routines in this >package. ( The >assembler portion is not linked in from the library) Anton, I'd appreciate it if you could give me some more information on this. Maybe send me a map file of a program illustrating the issue with it no linked in. I'm working on the next release and I'd like to try and duplicate and fix this if I can. There are a couple of contact links on the website and they should get through to me. You can just send a quick note and we can exchange address's for more in depth conversation if you wish. Robert " 'Freedom' has no meaning of itself. There are always restrictions, be they legal, genetic, or physical. If you don't believe me, try to chew a radio signal. " Kelvin Throop, III |
Reply by ●February 24, 20052005-02-24
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--- In , "tiogate" <gate@t...> wrote: > > --- In , "ntfreak2000" <ntfreak2@h...> wrote: > >> > > All depends on what c library you are using, with newlib you need > to > > override _write or _write_r (reentrant version) eg. > > > > Spen > > I am not sure, but I think I am not using newlib. The hint is: there > is no reent.h available. The package I installed was GCCARM331 > downloaded from Keil Evaluation > (http://www.keil.com/demo/evaldl.asp). The Manuals mention "GNUPro > Tools" and there is not one occurrence of the word "newlib" in them. > > Does anybody know what libs are these, and which function(s) I > should override? > > Fernando Keil gcc uses uclibc, the version you require is: int write (int file, char * ptr, int len) { return len; } All the system functions are just non reentrant versions. Be careful of uisng uclibc as a clib, even though it is a better lib for smaller devices it comes under lgpl rather than gpl. This is only really a problem if you are statically linking with the libs. Regards Spen |
Reply by ●February 25, 20052005-02-25
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Yes, you are right. I've overridden write() and now printf outputs to UART0. Thank you. Fernando --- In , "ntfreak2000" <ntfreak2@h...> wrote: > > Keil gcc uses uclibc, the version you require is: > > int write (int file, char * ptr, int len) > { > return len; > } > All the system functions are just non reentrant versions. > > Be careful of uisng uclibc as a clib, even though it is a better lib > for smaller devices it comes under lgpl rather than gpl. This is only > really a problem if you are statically linking with the libs. > > Regards > Spen |
Reply by ●February 25, 20052005-02-25
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On 24 Feb 2005 at 17:46, Robert Adsett wrote: > > At 07:03 PM 2/24/05 +0200, Anton Erasmus wrote: > >If you are using the gcc toolset, then you are probably using > >newlib. Hence you need to port newlib to your specific hardware. Look > >for "Porting Newlib" and you should find a fair amount of info. There > >is such a porting library for the LPC. You can download it at > >http://www.aeolusdevelopment.com/Articles/download.html. There are > >some issues when using the interrupt uart routines in this package. ( > >The assembler portion is not linked in from the library) > > Anton, I'd appreciate it if you could give me some more information on > this. Maybe send me a map file of a program illustrating the issue > with it no linked in. I'm working on the next release and I'd like to > try and duplicate and fix this if I can. There are a couple of > contact links on the website and they should get through to me. You > can just send a quick note and we can exchange address's for more in > depth conversation if you wish. Murphy strikes again :-( - I tried the same thing on my home machine as I did at work, and of course now I do not get the same thing. I have an older version of cygwin installed at work, but otherwise everything is the same. I have only compiled the examples at home - direct link as well as linking with the library. I haven't tried executing the examples. Example test10 executes correctly when linking directly with the library object files, but when linked agains the library (No errors reported), the example does not execute correctly. (No serial output). I will try the hex files I compiled at home on monday to see if both version work. Regards Anton Erasmus -- A J Erasmus |
Reply by ●February 27, 20052005-02-27
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At 07:37 PM 2/25/05 +0200, Anton Erasmus wrote: >Murphy strikes again :-( - I tried the same thing on my home machine as I did >at work, and of course now I do not get the same thing. I have an older >version >of cygwin installed at work, but otherwise everything is the same. I have >only compiled >the examples at home - direct link as well as linking with the library. I >haven't tried >executing the examples. Example test10 executes correctly when linking >directly with >the library object files, but when linked agains the library (No errors >reported), the >example does not execute correctly. (No serial output). I will try the hex >files I compiled >at home on monday to see if both version work. I appreciate the effort Anton. Robert " 'Freedom' has no meaning of itself. There are always restrictions, be they legal, genetic, or physical. If you don't believe me, try to chew a radio signal. " Kelvin Throop, III |
