AVR Freaks

I made the same mistake some time ago and ordered based on the 128x64 and when I got them...well let's just say it's not what I expected.

The 0.96 inch measurement is done diagonally which tricks us into thinking the size is big but in reality its small.

A good search term for usable sized OLED displays is "2.42 inch" such as these: https://www.ebay.co.uk/itm/23323...

Lovely displays, but they ain't cheap! They cost more than the rest of the project put together, including pcb, processor, and bluetooth module.

Neil

I bought twenty of them last time round and i think I got a discount on the advertised seventeen euros.

But if you recall my building a widget video I posted recently, you will understand why the display goes on last!

Neil

There is this one I used in the past.

https://github.com/efthymios-ks/AVR-SSD1306

On arduino platform the following one is popular.

https://github.com/adafruit/Adafruit_SSD1306

SH1107 (datasheet)

Sino Wealth | OLED-Info

all due to a search on OLED at gallery · olikraus/u8g2 Wiki · GitHub

Search results for: 'sh1107' (Seeed Technology)

Raspberry Pi Pico OLED module is out of stock

Raspberry Pi is now a microcontroller | AVR Freaks

Graphical u8glib editor using library primitives | AVR Freaks

u8g2setupcpp · olikraus/u8g2 Wiki · GitHub

Your UNO will not have pull ups, unless you enable the internal port pull ups, but a lot of Arduino modules with I2C have them, look at your display.  

I would think the level convert would have them! 

jim

The part I suggested is SPI, not I2C - something I much prefer - and I rolled my own interface. This is for an STM ARM chip, using their HAL code to initialise the SPI interface.

There's a 1k buffer used to which I draw; this code takes that buffer and sends it to the display. There's also an array of characters making up the font which I can supply if people want.

/*
 * ssd1309.c
 *
 *  Created on: Dec 19, 2020
 *      Author: barnacle
 *      many hints taken from https://github.com/afiskon/stm32-ssd1306/tree/master/ssd1306
 */

#include "ssd1309.h"
#include <stdio.h>
#include <string.h>

extern SPI_HandleTypeDef hspi1;		// the previously defined handle for the oled spi

void ssd1309_init (void)
{
	// initialise the display for further use
	ssd1309_CS_HI						// deselect oled
	ssd1309_RES_LO						// reset
	HAL_Delay (10);						// hold
	ssd1309_RES_HI
	HAL_Delay (100);					// wait for screen to boot

	ssd1309_write_command (0xae);		// display off

    ssd1309_write_command (0x20); 		// Set Memory Addressing Mode
    ssd1309_write_command (0x02); 		// 00b,Horizontal Addressing Mode; 01b,Vertical Addressing Mode;
                                		// 10b,Page Addressing Mode (RESET); 11b,Invalid

    ssd1309_write_command (0xB0); 		// Set Page Start Address for Page Addressing Mode,0-7

    ssd1309_write_command (0xC8); 		// Set COM Output Scan Direction

    //ssd1309_write_command (0x2e);		// disable horizontal scroll

    ssd1309_write_command (0xa0);

    ssd1309_write_command (0x02); 		// ---set low column address
    ssd1309_write_command (0x10); 		// ---set high column address (low nibbles so 0x00)

	ssd1309_write_command (0x40); 		// --set start line address - CHECK

    ssd1309_write_command (0x81);
    ssd1309_write_command (0xff);		// contrast max

    ssd1309_write_command (0xA1); 		//--set segment re-map 0 to 127 - CHECK

    ssd1309_write_command (0xA6); 		//--set normal color

    ssd1309_write_command (0xA8); 		//--set multiplex ratio(1 to 64) - CHECK
    ssd1309_write_command (0x3F); 		//

    ssd1309_write_command (0xA4); 		// 0xa4,Output follows RAM content;0xa5,Output ignores RAM content

    ssd1309_write_command (0xD3); 		// -set display offset - CHECK
    ssd1309_write_command (0x00); 		// -not offset

    ssd1309_write_command (0xD5); 		// --set display clock divide ratio/oscillator frequency
    ssd1309_write_command (0xF0); 		// --set divide ratio

    ssd1309_write_command (0xD9); 		// --set pre-charge period
    ssd1309_write_command (0x22); 		//

    ssd1309_write_command (0xDA); 		// --set com pins hardware configuration - CHECK
    ssd1309_write_command (0x12);

    ssd1309_write_command (0xDB); 		// --set vcomh
	ssd1309_write_command (0x20); 		// 0x20,0.77xVcc

    ssd1309_write_command (0x8D); 		// --set DC-DC enable
    ssd1309_write_command (0x14); 		//

    ssd1309_write_command (0xaf);		// and turn display on
}

void ssd1309_write_command (uint8_t command)
{
	// send a single byte to the command register
	ssd1309_CS_LO
	ssd1309_DC_COMM
	HAL_SPI_Transmit (&hspi1, &command, 1, 100);
	ssd1309_CS_HI
}

void ssd1309_write_data (uint8_t * data, uint8_t count)
{
	ssd1309_CS_LO
	ssd1309_DC_DATA
	HAL_SPI_Transmit (&hspi1, data, count, 100);
	ssd1309_CS_HI
}

void ssd1309_write_page (uint8_t * video)
{
	// dump the video ram to the display in one hit
	// assumes page mode
	// for reasons best known to the designer, the pixels appear to be in order
	// 64-128, 0-63 so we draw each line in two chunks
	for (uint8_t y = 0; y < 8; y++)
	{
		ssd1309_write_command (0xb0 + y);
		ssd1309_write_command (0x00);
		ssd1309_write_command (0x10);
		ssd1309_write_data (&video[(y * 128)], 128);
	}
}

void ssd1309_image_to_video (uint8_t * image, uint8_t * video)
{
	// we receive a pointer to the first byte of the image data
	// images are 120 vertical slices of 32 pixels each.
	// It's a long story... but I'm not changing them now.

	for (int q=0; q<120; q++)
	{
		// odd offset to centre the image horizontally and vertically
		video [648 + q] = image[0 + (q * 4)];
		video [520 + q] = image[1 + (q * 4)];
		video [392 + q] = image[2 + (q * 4)];
		video [264 + q] = image[3 + (q * 4)];
	}
}

void ssd1309_cls (uint8_t * video)
{
	// clears the video space but does *not* update the display
	for (int q = 0; q < 1024; q++)
	{
		video[q] = 0;
	}
}

void ssd1309_print_char (uint8_t * video, uint8_t ch, int * col, int * row)
{
	// print the specified char at row and column in the video ram, updating col but not row
	// row is 0-3 from the top downwards using pages 0-1, 2-3, 4-5, and 6-7 of the video
	// does not update the screen directly, just the display buffer 'video'

	extern uint8_t fonts[960];
	int font_ptr;
	int video_ptr;

	if (*col > 20)
	{
		return;		// trying to write past the end of the memory
	}

	// find the offset for the character
	font_ptr = (ch - 0x20) * 10;				// ten font bytes per character
	video_ptr = (*row * 256) + (*col * 6);
	for (int q = 0; q < 5; q++)
	{
		video[video_ptr + q] = fonts[font_ptr + (q * 2) + 1];
	}
	video[video_ptr + 5] = 0;					// top row done

	video_ptr += 128;							// one line down and six slots left
	for (int q = 0; q < 5; q ++)
	{
		video[video_ptr + q] = fonts[font_ptr + (q * 2)];
	}
	video[video_ptr + 5] = 0;					// bottom row done

	(*col)++;
}

void ssd1309_print_str (uint8_t * video, const char * str, int * col, int * row)
{
	// print a zero terminated string to the screen
	const char * ptr = str;
	while (*ptr != '\0')
	{
		ssd1309_print_char (video, *ptr, col, row);
		ptr++;
	}
}

Neil