Buffer and PROGMEM

hello, i'm working 128x64 lcd screen , using adafruit library adafruit_ssd1306

in code, initialized screen adafruit splash screen. it's pretty hefty burden on memory, having on start up. below how byte array stored in library:

code: [select]

static uint8_t buffer[ssd1306_lcdheight * ssd1306_lcdwidth / 8] = {
0x00, 0x00, blah blah lots of hex codes,  0x00
};

void adafruit_ssd1306::display(void) {

    (uint16_t i=0; i<(ssd1306_lcdwidth*ssd1306_lcdheight/8); i++) {
      fastspiwrite(buffer[i]);
      //ssd1306_data(buffer[i]);
    }
}


my question is, can byte array of buffer, bytes, moved progmem better storage? @ save dynamic memory?

i tried using

code: [select]


const uint8_t intro[ssd1306_lcdheight * ssd1306_lcdwidth / 8] progmem = { 0x00 etc};
static uint8_t buffer[ssd1306_lcdheight * ssd1306_lcdwidth / 8] = {intro};


but didn't save memory @ all. it's giving me "invalid conversion" warning

quote from: tggeko on nov 21, 2017, 03:29 am

hello, i'm working 128x64 lcd screen , using adafruit library adafruit_ssd1306

in code, initialized screen adafruit splash screen. it's pretty hefty burden on memory, having on start up. below how byte array stored in library:

here's snippet program of mine. array of infrared remote codes stored in progmem, show how other type of data:

code: [select]

///////////////////////////////////////////////////////////////////////////////
// sony camera shutter release code 0xb4b8f (focus , shoot)
///////////////////////////////////////////////////////////////////////////////
static const uint16_t shutter[] progmem = {
    // header
    0x8060, 0x0018,
    // data
    0x8030, 0x0018, 0x8018, 0x0018, 0x8030, 0x0018, 0x8030, 0x0018, // b
    0x8018, 0x0018, 0x8030, 0x0018, 0x8018, 0x0018, 0x8018, 0x0018, // 4
    0x8030, 0x0018, 0x8018, 0x0018, 0x8030, 0x0018, 0x8030, 0x0018, // b
    0x8030, 0x0018, 0x8018, 0x0018, 0x8018, 0x0018, 0x8018, 0x0018, // 8
    0x8030, 0x0018, 0x8030, 0x0018, 0x8030, 0x0018, 0x8030, 0x01c8, // f
    // end of data block
    0x0000
};

note storing uint16_t values, whereas need uint8_t... change it.

also note have read data using "pgm_read_byte (pointer + index)" instead of accessing array directly sram:

code: [select]

uint8_t array_size = sizeof (array) / sizeof (*array); // uint16_t if array > 255 elements
uint8_t index; // uint16_t if array > 255 elements
uint16_t data; // same type data in array

for (index = 0; index < array_size; index++) {
    data = pgm_read_word(array + index); // pgm_read_byte 8 bit data!
    // send data wherever
}

hope helps.

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