Basic question: String/ Char. output to LCD/ UART

[L C]

Posted on May 29, 2017 at 03:04

Hello!

I have success to access LCD(ili9341).

And let it display characters. Note the code for string/char to LCD display still under develop.

In general of C, many case use 'printf' for output.

Q1) How can I to use 'printf'? e.g. include stdio.h and then ....?

Sorry I am beginner of C, please give me some information/guild to lean,.

In AVR, they have something to transfer printf string stream to specific LCD driver.

static FILE mydata = FDEV_SETUP_STREAM(ili9341_putchar_printf, NULL, _FDEV_SETUP_WRITE);//mydata declaration and converting it into stream

Q2) How to manage printf for different kind of output such LCD & UART?

In some system, they have LCD for display(in operation) AND using UART communicate with PC for remote/ data logging or trace logging.

If only one 'printf', how to operate between different output device.

Please share your comment/ experience to me.

BR

LC

[Tesla DeLorean]

Posted on May 29, 2017 at 04:51

Depends on the tool chain, with Keil I can implement a routine to send a character to multiple output devices. I could use fprintf() and a handle to output to specific devices.

Consider using sprintf(), and then push the string buffer to the devices you want to use.

[L C]

Posted on May 29, 2017 at 06:20

Clive One

Thanks for your comment.

I am using IAR for software development.

Do you have implementation information with IAR for me?

As you said that '

I could use fprintf() and a handle to output to specific devices.'.

Is it necessary specifier devices before use

 fprintf()?

BR

LC

[Tesla DeLorean]

Posted on May 29, 2017 at 16:30

I don't actively use IAR tools, you'll need to review the documentation/examples related to the tools you have chosen.

GNU/GCC and Keil provide means to provide board specific character IO functions.

fprintf() provides for a FILE handle to be passed, and that could be managed in the fputc() retargeting code.

[AvaTar]

Posted on May 29, 2017 at 16:49

As far as I remember, the IAR WB has a detailed tutorial for redirecting console output.

But IMHO

fprintf()

is not the best way.

Files are an OS metaphor, and the OS is missing here.

I would use

sprintf()

and work on strings, as suggested earlier.

[Tesla DeLorean]

Posted on May 29, 2017 at 19:07

fprintf() provides a standard method to get output to different devices/streams, whether you use the handle as a 32-bit constant, or a pointer to a user defined structure. Generally avoids having to reinvent the wheel or create non-portable code. People should pick what's appropriate for them.

[L C]

Posted on June 01, 2017 at 08:44

Hi ALL

I still cannot output string to LCD module.

Please share a code for my reference.

BR

LC

[LMI2]

Posted on June 01, 2017 at 16:36

There are much more working libraries for Arduino boards. For your display also I think. Here you are supposed to make your own, or if you are lucky a library can be found (with Google). There are some working examples or APIs for displays which are meant for STM32 devices.

https://github.com/MaJerle/stm32fxxx_hal_libraries

  or

http://majerle.eu/

  has interesting libraries too.

BSP_LCD_DisplayStringAt(oma, BSP_LCD_GetYSize() / 2 + 45,(uint8_t *) buffer, CENTER_MODE); works for STM32F746 Discovery board. It has a LCD display.

[L C]

Posted on June 03, 2017 at 09:01

Hi mich.lei

In before, I am testing all(every related LCD) code in ''main.c'' and it work fine in compile.

I move all code and relative reference(include & define) to separated file(ili9341.c & ili9341.h).

Of cause, the preprocessor has updated with location for them.

Unfortunately, there have error in linking and show below.

 

Please help me and give me your comment.

BR

Lewis

[LMI2]

Posted on June 03, 2017 at 16:52

I am afraid I can't help you much with linking. I just fight back when my IDE does something odd. Besides, you seem to use different IDE  than I.

If you have a IDE/linking problem, why don't you start a new discussion about that?