Printf and serial port

Giuseppe Marullo wrote:
> Hi all,
> just bought a Xylo-LM FPGA board with a LPC2138 onboard. I have a very
> simple question, I use Yagarto/Eclipse/OpenOCD etc. etc I don't know how
> to get the printf messages out.
Yagarto includes the newlib which offer stdio-functions like printf (and
the smaller variant iprintf). You have to "bind" the stdio-system with
the serial-port and provide some low-level functions for initialize and
send characters to the UART. It may be easier to avoid stdio and use
simple functions like uart1_puts() to output characters. For real stdio
the newlib needs some hardware-interface-functions (syscalls, some kind
of simpel BIOS). You may use the ready-made newlib-lpc or create your
own simple set of syscalls.

> which is supposed to be the default sdtout for them?
There is no default since this depends on the used lower-level
interface. See the newlib libc.pdf.

> Is it a serial port and is it configurable?
Not by default, it can be "anything". Configuration and usage depends on
the interface-layer between newlib-stdio-functions and the LPC2138
hardware.

Martin Thomas wrote:
> Giuseppe Marullo wrote:
>> Hi all,
>> just bought a Xylo-LM FPGA board with a LPC2138 onboard. I have a very
>> simple question, I use Yagarto/Eclipse/OpenOCD etc. etc I don't know how
>> to get the printf messages out.
> Yagarto includes the newlib which offer stdio-functions like printf (and
> the smaller variant iprintf). You have to "bind" the stdio-system with
> the serial-port and provide some low-level functions for initialize and
> send characters to the UART. It may be easier to avoid stdio and use
> simple functions like uart1_puts() to output characters. For real stdio
> the newlib needs some hardware-interface-functions (syscalls, some kind
> of simpel BIOS). You may use the ready-made newlib-lpc or create your
> own simple set of syscalls.
>
>> which is supposed to be the default sdtout for them?
> There is no default since this depends on the used lower-level
> interface. See the newlib libc.pdf.
>
>> Is it a serial port and is it configurable?
> Not by default, it can be "anything". Configuration and usage depends on
> the interface-layer between newlib-stdio-functions and the LPC2138
> hardware.

I was thinking it was a newbie thing. I will take a look at the docs.

Thanks,

Giuseppe

Giuseppe Marullo wrote:
> Martin Thomas wrote:
>> Giuseppe Marullo wrote:
>>> Hi all,
>>> just bought a Xylo-LM FPGA board with a LPC2138 onboard. I have a very
>>> simple question, I use Yagarto/Eclipse/OpenOCD etc. etc I don't know how
>>> to get the printf messages out.
>> Yagarto includes the newlib which offer stdio-functions like printf (and
>> the smaller variant iprintf). You have to "bind" the stdio-system with
>> the serial-port and provide some low-level functions for initialize and
>> send characters to the UART. It may be easier to avoid stdio and use
>> simple functions like uart1_puts() to output characters. For real stdio
>> the newlib needs some hardware-interface-functions (syscalls, some kind
>> of simpel BIOS). You may use the ready-made newlib-lpc or create your
>> own simple set of syscalls.
>>
>>> which is supposed to be the default sdtout for them?
>> There is no default since this depends on the used lower-level
>> interface. See the newlib libc.pdf.
>>
>>> Is it a serial port and is it configurable?
>> Not by default, it can be "anything". Configuration and usage depends on
>> the interface-layer between newlib-stdio-functions and the LPC2138
>> hardware.
>
> I was thinking it was a newbie thing. I will take a look at the docs.
>
> Thanks,
>
> Giuseppe

Hi!!

This works for me:

int __putchar(int ch){
  if (ch == '\n')
    UARTWriteChar('\r');
  UARTWriteChar(ch);
}


__putchar() is a function that send out single characteres to whatever
you want, in my case to a serial port, and this is used as a primitive
by functions like printf(), puts(), etc.

Just add it to your source code and write inside the code to do
something with the characteres (serial port, LCD, usb, etc)

> This works for me:
>
> int __putchar(int ch){

What toolchain/toolset/package are you using?

Martin Thomas wrote:
>> This works for me:
>>
>> int __putchar(int ch){
>
> What toolchain/toolset/package are you using?

Hi!!

I'm using CrossWorks 1.5. There's must something similar for the GNU
toolchain (e.g. winarm) and, for 8 bits, the CodeWarrior for HCS08 has
functions alike

Javier Rod wrote:
> Martin Thomas wrote:
>>> This works for me:
>>>
>>> int __putchar(int ch){
>>
>> What toolchain/toolset/package are you using?
>
> Hi!!
>
> I'm using CrossWorks 1.5. There's must something similar for the GNU
> toolchain (e.g. winarm) and, for 8 bits, the CodeWarrior for HCS08 has
> functions alike

Hi all, sorry for the extreme delay.

>This works for me:
I tried to understand where to redefine a similar function but failed.
At this point is not even clear to me if yagarto already uses newlib-lpc
or simply newlib.

AFAIK, newlib-lpc does not use _putchar etc. so this is not the right
way to do it, there should be something line write function or so.

Actually, I tried to use this much simpler demo of iprintf/printf, that
should do the trick (from a Martin Thomas page):
http://www.siwawi.arubi.uni-kl.de/avr_projects/arm_projects/#gcc_stdio

If I understand correctly, this will implment a simple iprintf/printf on
a uart using a subset of the newlib-lpc (basically newlib-lpc is not
needed).

Initially, I was not able to build in Eclipse, just on command line.
Actually, I am able to build (I have imported the whole directory into a
new project), but not yet tested with the real hw (that is a LPC2138 and
not a LPC2129).

Giuseppe

Giuseppe Marullo wrote:
> Javier Rod wrote:
>> Martin Thomas wrote:
>>>> This works for me:
>>>>
>>>> int __putchar(int ch){
>>>
>>> What toolchain/toolset/package are you using?
>>
>> Hi!!
>>
>> I'm using CrossWorks 1.5. There's must something similar for the GNU
>> toolchain (e.g. winarm) and, for 8 bits, the CodeWarrior for HCS08 has
>> functions alike
>
> Hi all, sorry for the extreme delay.
>
>>This works for me:
> I tried to understand where to redefine a similar function but failed.
> At this point is not even clear to me if yagarto already uses newlib-lpc
> or simply newlib.

As far as I know newlib-lpc is not included in Yagarto. I have in
included it in WinARM. But you could build the library yourself. The
source is available (google for newlib-lpc). newlib-lpc is not a
replacement for the newlib. It's just a implementation of the syscalls
for the "real" newlib and some additional utility-code for most (older)
LPC2000.

> AFAIK, newlib-lpc does not use _putchar etc. so this is not the right
> way to do it, there should be something line write function or so.

newlib-lpc provides syscalls, everything else comes from newlib. See the
libc.pdf from newlib.

> Actually, I tried to use this much simpler demo of iprintf/printf, that
> should do the trick (from a Martin Thomas page):
> http://www.siwawi.arubi.uni-kl.de/avr_projects/arm_projects/#gcc_stdio
>
> If I understand correctly, this will implment a simple iprintf/printf on
> a uart using a subset of the newlib-lpc (basically newlib-lpc is not
> needed).

It implements some syscalls. Yes, I have used the newlib-lpc code to
learn how this can be done.

Martin,
many thanks for your help.

> As far as I know newlib-lpc is not included in Yagarto. I have in
> included it in WinARM. But you could build the library yourself. The
Ok, I am testing with my board but without luck. I am able to build the
project but (I guess) since I have a .ld for the LPC2129 need to have it
adapted to LPC2138.
I am not able to debug it.

I took the file from another sample on your pages
(http://www.siwawi.arubi.uni-kl.de/avr_projects/arm_projects/lpc2138_mcb2130_freeRTOSdemo_20060519.zip).
I have changed:

SUBMDL   = LPC2138
into Makefile but it gives me these errors:


**** Build of configuration Default for project p ****

...

Linking: ADC.elf
arm-elf-gcc -mthumb -mcpu=arm7tdmi-s -mthumb-interwork -I. -gdwarf-2
-DROM_RUN -D__WinARM__  -Os -Wall -Wcast-align -Wimplicit
-Wpointer-arith -Wswitch -Wredundant-decls -Wreturn-type -Wshadow
-Wunused -Wa,-adhlns=crt0.lst   -Wcast-qual -MD -MP -MF .dep/ADC.elf.d
crt0.o   ADC.o syscalls.o uart.o     --output ADC.elf -nostartfiles
-Wl,-Map=ADC.map,--cref -lc  -lm -lc -lgcc     -T./LPC2138-ROM.ld
crt0.o: In function `abort':
C:\data\eclipse\p/crt0.S:216: undefined reference to `_stack'
C:\data\eclipse\p/crt0.S:216: undefined reference to `__bss_start'
C:\data\eclipse\p/crt0.S:216: undefined reference to `_etext'
C:\data\eclipse\p/crt0.S:216: undefined reference to `_data'
C:\data\eclipse\p/crt0.S:216: undefined reference to `_edata'
C:\data\eclipse\p/crt0.S:216: undefined reference to `__ctors_start__'
C:\data\eclipse\p/crt0.S:216: undefined reference to `__ctors_end__'
collect2: ld returned 1 exit status
make: *** [ADC.elf] Error 1

I guess I may need a different crt.S lpc2138 specific (I was not able to
locate another one, beside the one provided with the board but seems to
use different names so I dubt it would do).

> source is available (google for newlib-lpc). newlib-lpc is not a
> replacement for the newlib. It's just a implementation of the syscalls
> for the "real" newlib and some additional utility-code for most (older)
> LPC2000.

It is far beyond my skills to compile it at the moment, I don't even
know where to start

> It implements some syscalls. Yes, I have used the newlib-lpc code to
> learn how this can be done.

Any chance you could do it for the lpc2138 too? :)

Giuseppe