ESP8266 Community Forum

Hi!
One of my small project consists of transferring an image from PC to ESP8266 which is connected to LCD ( for testing purposes I am using SSD1306 OLED screen). Images are changing every minute and are displayed with Adafruit GFX library. The setup is as follows:

1. 64x64 pixel monochrome BMP image is converted to hex string, like : "0x00, 0x00, 0x00, 0x00, 0x00, 0x00 etc.". It is saved as hex.txt;
2. hex.txt is transferred to ESP-12E SPIFFS. It could also be transferred as any other format, too.
3. Adafruit GFX library function for showing the image is as follows:

// drawBitmap() variant for RAM-resident (not PROGMEM) bitmaps.
drawBitmap(int16_t x, int16_t y, uint8_t *bitmap, int16_t w, int16_t h, uint16_t color

, where "uint8_t *bitmap" is the source for that hex tring ("0x00, 0x00, 0x00, 0x00, 0x00, 0x00 etc.").

Sadly I have no programming background, therefore I have problems with loading and converting that hex.txt from SPIFFS to "uint8_t *bitmap" and still getting no errors on compiling the code.

What would be the right way to load the hex.txt and convert it to format which Adafruit GFX needs ( "uint8_t *bitmap" ) ?

P.S. I have no problems with loading the same image from PROGMEM.


Thanks!

Saddly, no answer

Anway, this script compiles without problems, but the image is messed up (as opposite to the same image displayed from PROGMEM)


File f;

f = SPIFFS.open("/data/image_hex.txt", "r");

if (f) {
int s = f.size();
Serial.printf("File Opened , Size=%d\r\n", s);


String data = f.readString();
uint8_t data1[data.length()];
data.getBytes(data1, data.length());


//Serial.println(data);


f.close();

display.drawBitmap(30, 0, data1, 64, 64, WHITE);
display.display();
delay(1000);



} else {
Serial.println("File Not Opened");
}

Its a string of HEX chars "0x00" not a single "byte" like the display function probably requires.

"0x00" is 4 bytes, 5 if you count a possible trailing nul terminator of zero.

RichardS