OLED 0,96 - problem with displaying a variable

[szymonsmolka]

Ask any question, you have, regarding the library
Hi. I'm trying to use the lcdgfx library to run a 0.96 64x128 OLED display with the SH1107 driver. I wanted to make a simple thermometer. The temperature is assigned to the float variable, but the display does not show it.
display.printFixed (0, 0, temp, STYLE_BOLD);

How do I enter such a code for example
display.printFixed (0, 0, "TEST", STYLE_BOLD);

The display works and shows TEST

Where is the problem? Please help.

[lexus2k]

Please, try:

    display.setTextCursor(0,0);
    display.print( temp );

The function supports only int variables

[szymonsmolka]

The temperature is displayed. Thank you. However, there is no decimal value. Is there a way to do this?
Can the font size be changed in this function?

[lexus2k]

@szymonsmolka

I'm sorry for the delay. Actually you can display any numbers you want like this:

   char str[10];
   sprintf( str, "%.2f", temp );
   display.print( str );

[szymonsmolka]

No problem :) But it doesn't help. The value of 1266 is displayed all the time. Fortunately, I managed differently with decimal values.
Unfortunately, I can't enlarge the font. Is it possible at all?

[szymonsmolka]

char str[10];
   sprintf( str, "%.2f", temp );
   display.print( str );

Have an idea why the value 1266 is displayed?

[lexus2k]

Hi, I'm sorry, that was the wrong location of f character in format string.
I fixed the format string in the examples above.

Anyway, there is very rich documentation on printf and sprintf functions over internet. Please refer to documentation.

[lexus2k]

[lexus2k]

Can the font size be changed in this function?

No, the only supported feature is for monochrome displays. printFixedN

[szymonsmolka]

Anyway, there is very rich documentation on printf and sprintf functions over internet. Please refer to documentation.

After your answer, I did so. The code looks fine, and so on it returns 1266. For example, if I change str [10] to str [15], the value is 1249. Can you take a look at what's wrong with the code?

`#include "lcdgfx.h"
#include "lcdgfx_gui.h"
#include <Arduino.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#include <Wire.h>

OneWire oneWire(A0);
DallasTemperature sensors(&oneWire);

DisplaySH1107_64x128_I2C display(-1);

float temp;

void setup()
{
display.begin();
display.setFixedFont(ssd1306xled_font6x8);
display.clear();
display.fill(0x00);
sensors.begin();
}

void loop()
{

sensors.requestTemperatures();
temp = sensors.getTempCByIndex(0);

display.setTextCursor(0, 64);
char str[10];
sprintf( str, "%.2f", temp );
display.print( str );

delay (5000);

}`

[lexus2k]

Which version of Arduino IDE are you using? Does it display any warnings / errors?

Try this code:

char str[10];
sprintf( str, "%.2f", temp );
display.write( str );

[szymonsmolka]

Which version of Arduino IDE are you using?

Arduino IDE 1.8.13

Does it display any warnings / errors?

Summary after upload:

Sketch uses 10044 bytes (70%) of program storage space. Maximum is 14336 bytes.
Global variables use 336 bytes (32%) of dynamic memory, leaving 688 bytes for local variables. Maximum is 1024 bytes.

char str[10];
sprintf( str, "%.2f", temp );
display.write( str );

After this change, the display only shows a question mark :(
Also no warnings.

[lexus2k]

I don't have all those sensors. so I commented out the code reading the temperature, and replaced it with single assignment. And it works. So the issue somewhere in another library, and not in lcdgfx

#include "lcdgfx.h"
#include "lcdgfx_gui.h"
//#include <Arduino.h>
//#include <OneWire.h>
//#include <DallasTemperature.h>
//#include <Wire.h>

//OneWire oneWire(A0);
//DallasTemperature sensors(&oneWire);

DisplaySH1107_64x128_I2C display(-1);

float temp;

void setup()
{
  display.begin();
  display.setFixedFont(ssd1306xled_font6x8);
  display.clear();
  display.fill(0x00);
  // sensors.begin();
}

void loop()
{

  // sensors.requestTemperatures();
  temp = 23.23; // sensors.getTempCByIndex(0);

  display.setTextCursor(0, 64);
  char str[10];
  sprintf( str, "%.2f", temp );
  display.write( str );

  delay (5000);

}

The result:

[szymonsmolka]

An interesting thing. When I do what you did, it still displayed a question mark. Maybe my display is broken.

[lexus2k]

@szymonsmolka What about direct_draw/draw_text example? Can you capture the result for that example for me?

[szymonsmolka]

@szymonsmolka What about direct_draw/draw_text example? Can you capture the result for that example for me?

@lexus2k

https://github.com/lexus2k/lcdgfx/blob/master/examples/direct_draw/draw_text/draw_text.ino

Not working. The same result. Question mark.

[Mephisto68]

Can the font size be changed in this function?

No, the only supported feature is for monochrome displays. printFixedN

Hello,
We cannot "send" this to the screen:
Display.printFixedN(10, 52, var, STYLE_NORMAL, FONT_SIZE_2X);
But what a shame not to be able to do that!
I will have to get another library
However, yours is so good!
Would it not be possible in a future version to add this function?
Thanks.

[Mephisto68]

include "lcdgfx.h"
#include "lcdgfx_gui.h"

/* LCD */
#define PORT_ECRAN_RESET 10
#define PORT_ECRAN_CS 8
#define PORT_ECRAN_DC 9
#define PORT_ECRAN_MOSI_SDA 11
#define PORT_ECRAN_SCK_SCL 13
#define PORT_ECRAN_ECLAIRAGE 7
DisplayST7735_128x128x16_SPI display = DisplayST7735_128x128x16_SPI(PORT_ECRAN_RESET,{-1, PORT_ECRAN_CS, PORT_ECRAN_DC, 0, PORT_ECRAN_MOSI_SDA, PORT_ECRAN_SCK_SCL});

float temp;

void setup()
{
display.begin();
display.setFixedFont(ssd1306xled_font6x8);
display.clear();
display.fill(0x00);
// sensors.begin();
}

void loop()
{

// sensors.requestTemperatures();
temp = 23.23; // sensors.getTempCByIndex(0);

display.setTextCursor(20, 20);
char str[10];
sprintf( str, "%.2f", temp );
display.write( str );

delay (5000);

}

RESULT : the display only shows a question mark :(

[lexus2k]

Hi,

I apologize for this inconvenience. However the library has some limitations to reduce flash ram usage.
New functionality can be implemented, it requires some time.

Best regards,
Aleksei