237 lines
7.1 KiB
C
237 lines
7.1 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <linux/i2c-dev.h>
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#include <fcntl.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include "ssd1306.h"
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// this code is mainly based on Bakebit software: https://github.com/friendlyarm/BakeBit
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#define ARRAY_OF(x) (sizeof(x)/sizeof(x[0]))
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#define I2C_BUS "/dev/i2c-0"
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#define OLED_ADDR 0x3c
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#define OLED_COMMAND_MODE 0x00
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#define OLED_DATA_MODE 0x40
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#define OLED_DISPLAY_OFF_CMD 0xae
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#define OLED_DISPLAY_ON_CMD 0xaf
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static const uint8_t font[][8] = {
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{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},
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{0x00,0x00,0x5F,0x00,0x00,0x00,0x00,0x00},
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{0x00,0x00,0x07,0x00,0x07,0x00,0x00,0x00},
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{0x00,0x14,0x7F,0x14,0x7F,0x14,0x00,0x00},
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{0x00,0x24,0x2A,0x7F,0x2A,0x12,0x00,0x00},
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{0x00,0x23,0x13,0x08,0x64,0x62,0x00,0x00},
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{0x00,0x36,0x49,0x55,0x22,0x50,0x00,0x00},
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{0x00,0x00,0x05,0x03,0x00,0x00,0x00,0x00},
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{0x00,0x1C,0x22,0x41,0x00,0x00,0x00,0x00},
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{0x00,0x41,0x22,0x1C,0x00,0x00,0x00,0x00},
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{0x00,0x08,0x2A,0x1C,0x2A,0x08,0x00,0x00},
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{0x00,0x08,0x08,0x3E,0x08,0x08,0x00,0x00},
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{0x00,0xA0,0x60,0x00,0x00,0x00,0x00,0x00},
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{0x00,0x08,0x08,0x08,0x08,0x08,0x00,0x00},
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{0x00,0x60,0x60,0x00,0x00,0x00,0x00,0x00},
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{0x00,0x20,0x10,0x08,0x04,0x02,0x00,0x00},
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{0x00,0x3E,0x51,0x49,0x45,0x3E,0x00,0x00},
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{0x00,0x00,0x42,0x7F,0x40,0x00,0x00,0x00},
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{0x00,0x62,0x51,0x49,0x49,0x46,0x00,0x00},
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{0x00,0x22,0x41,0x49,0x49,0x36,0x00,0x00},
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{0x00,0x18,0x14,0x12,0x7F,0x10,0x00,0x00},
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{0x00,0x27,0x45,0x45,0x45,0x39,0x00,0x00},
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{0x00,0x3C,0x4A,0x49,0x49,0x30,0x00,0x00},
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{0x00,0x01,0x71,0x09,0x05,0x03,0x00,0x00},
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{0x00,0x36,0x49,0x49,0x49,0x36,0x00,0x00},
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{0x00,0x06,0x49,0x49,0x29,0x1E,0x00,0x00},
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{0x00,0x00,0x36,0x36,0x00,0x00,0x00,0x00},
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{0x00,0x00,0xAC,0x6C,0x00,0x00,0x00,0x00},
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{0x00,0x08,0x14,0x22,0x41,0x00,0x00,0x00},
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{0x00,0x14,0x14,0x14,0x14,0x14,0x00,0x00},
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{0x00,0x41,0x22,0x14,0x08,0x00,0x00,0x00},
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{0x00,0x02,0x01,0x51,0x09,0x06,0x00,0x00},
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{0x00,0x32,0x49,0x79,0x41,0x3E,0x00,0x00},
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{0x00,0x7E,0x09,0x09,0x09,0x7E,0x00,0x00},
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{0x00,0x7F,0x49,0x49,0x49,0x36,0x00,0x00},
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{0x00,0x3E,0x41,0x41,0x41,0x22,0x00,0x00},
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{0x00,0x7F,0x41,0x41,0x22,0x1C,0x00,0x00},
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{0x00,0x7F,0x49,0x49,0x49,0x41,0x00,0x00},
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{0x00,0x7F,0x09,0x09,0x09,0x01,0x00,0x00},
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{0x00,0x3E,0x41,0x41,0x51,0x72,0x00,0x00},
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{0x00,0x7F,0x08,0x08,0x08,0x7F,0x00,0x00},
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{0x00,0x41,0x7F,0x41,0x00,0x00,0x00,0x00},
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{0x00,0x20,0x40,0x41,0x3F,0x01,0x00,0x00},
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{0x00,0x7F,0x08,0x14,0x22,0x41,0x00,0x00},
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{0x00,0x7F,0x40,0x40,0x40,0x40,0x00,0x00},
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{0x00,0x7F,0x02,0x0C,0x02,0x7F,0x00,0x00},
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{0x00,0x7F,0x04,0x08,0x10,0x7F,0x00,0x00},
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{0x00,0x3E,0x41,0x41,0x41,0x3E,0x00,0x00},
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{0x00,0x7F,0x09,0x09,0x09,0x06,0x00,0x00},
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{0x00,0x3E,0x41,0x51,0x21,0x5E,0x00,0x00},
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{0x00,0x7F,0x09,0x19,0x29,0x46,0x00,0x00},
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{0x00,0x26,0x49,0x49,0x49,0x32,0x00,0x00},
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{0x00,0x01,0x01,0x7F,0x01,0x01,0x00,0x00},
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{0x00,0x3F,0x40,0x40,0x40,0x3F,0x00,0x00},
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{0x00,0x1F,0x20,0x40,0x20,0x1F,0x00,0x00},
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{0x00,0x3F,0x40,0x38,0x40,0x3F,0x00,0x00},
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{0x00,0x63,0x14,0x08,0x14,0x63,0x00,0x00},
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{0x00,0x03,0x04,0x78,0x04,0x03,0x00,0x00},
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{0x00,0x61,0x51,0x49,0x45,0x43,0x00,0x00},
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{0x00,0x7F,0x41,0x41,0x00,0x00,0x00,0x00},
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{0x00,0x02,0x04,0x08,0x10,0x20,0x00,0x00},
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{0x00,0x41,0x41,0x7F,0x00,0x00,0x00,0x00},
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{0x00,0x04,0x02,0x01,0x02,0x04,0x00,0x00},
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{0x00,0x80,0x80,0x80,0x80,0x80,0x00,0x00},
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{0x00,0x01,0x02,0x04,0x00,0x00,0x00,0x00},
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{0x00,0x20,0x54,0x54,0x54,0x78,0x00,0x00},
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{0x00,0x7F,0x48,0x44,0x44,0x38,0x00,0x00},
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{0x00,0x38,0x44,0x44,0x28,0x00,0x00,0x00},
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{0x00,0x38,0x44,0x44,0x48,0x7F,0x00,0x00},
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{0x00,0x38,0x54,0x54,0x54,0x18,0x00,0x00},
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{0x00,0x08,0x7E,0x09,0x02,0x00,0x00,0x00},
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{0x00,0x18,0xA4,0xA4,0xA4,0x7C,0x00,0x00},
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{0x00,0x7F,0x08,0x04,0x04,0x78,0x00,0x00},
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{0x00,0x00,0x7D,0x00,0x00,0x00,0x00,0x00},
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{0x00,0x80,0x84,0x7D,0x00,0x00,0x00,0x00},
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{0x00,0x7F,0x10,0x28,0x44,0x00,0x00,0x00},
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{0x00,0x41,0x7F,0x40,0x00,0x00,0x00,0x00},
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{0x00,0x7C,0x04,0x18,0x04,0x78,0x00,0x00},
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{0x00,0x7C,0x08,0x04,0x7C,0x00,0x00,0x00},
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{0x00,0x38,0x44,0x44,0x38,0x00,0x00,0x00},
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{0x00,0xFC,0x24,0x24,0x18,0x00,0x00,0x00},
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{0x00,0x18,0x24,0x24,0xFC,0x00,0x00,0x00},
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{0x00,0x00,0x7C,0x08,0x04,0x00,0x00,0x00},
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{0x00,0x48,0x54,0x54,0x24,0x00,0x00,0x00},
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{0x00,0x04,0x7F,0x44,0x00,0x00,0x00,0x00},
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{0x00,0x3C,0x40,0x40,0x7C,0x00,0x00,0x00},
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{0x00,0x1C,0x20,0x40,0x20,0x1C,0x00,0x00},
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{0x00,0x3C,0x40,0x30,0x40,0x3C,0x00,0x00},
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{0x00,0x44,0x28,0x10,0x28,0x44,0x00,0x00},
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{0x00,0x1C,0xA0,0xA0,0x7C,0x00,0x00,0x00},
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{0x00,0x44,0x64,0x54,0x4C,0x44,0x00,0x00},
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{0x00,0x08,0x36,0x41,0x00,0x00,0x00,0x00},
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{0x00,0x00,0x7F,0x00,0x00,0x00,0x00,0x00},
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{0x00,0x41,0x36,0x08,0x00,0x00,0x00,0x00},
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{0x00,0x02,0x01,0x01,0x02,0x01,0x00,0x00},
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{0x00,0x02,0x05,0x05,0x02,0x00,0x00,0x00},
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};
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static const uint8_t init_commands[] = {
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0xAE, //display off
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0x00, //set lower column address
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0x10, //set higher column address
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0x40, //set display start line
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0xB0, //set page address
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0x81,
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0xCF, //0~255????????????????
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0xA1, //set segment remap
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0xA6, //normal / reverse
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0xA8, //multiplex ratio
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0x3F, //duty = 1/64
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0xC8, //Com scan direction
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0xD3, //set display offset
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0x00,
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0xD5, //set osc division
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0x80,
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0xD9, //set pre-charge period
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0xF1,
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0xDA, //set COM pins
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0x12,
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0xDB, //set vcomh
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0x40,
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0x8D, //set charge pump enable
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0x14,
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0xAF, //display ON
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};
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static int fd;
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static void send_command(uint8_t cmd)
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{
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uint8_t buf[2]= {
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[0] = OLED_COMMAND_MODE,
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[1] = cmd,
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};
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if (write(fd, buf, sizeof(buf)) != sizeof(buf)) {
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printf ("error while sending command\n");
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}
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}
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void send_data(uint8_t byte)
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{
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uint8_t buf[2] = {
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[0] = OLED_DATA_MODE,
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[1] = byte,
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};
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if (write(fd, buf, sizeof(buf)) != sizeof(buf)) {
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printf ("error while sending data\n");
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}
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}
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void ssd1306_set_position (uint32_t column, uint32_t row)
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{
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send_command(0xb0 + row); //set page address
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send_command(0x00 + (8*column & 0x0f)); //set column lower address
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send_command(0x10 + ((8*column>>4)&0x0f)); //set column higher address
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}
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void ssd1306_putc(char c)
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{
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if ((c<32) || (c>127)) // Ignore non-printable ASCII characters
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c=' ';
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c-=32;
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for (int i=0; i<8; i++) {
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uint8_t data=font[(int)c][i];
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send_data(data);
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}
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}
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void ssd1306_puts(const char* str)
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{
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while (*str != 0)
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ssd1306_putc(*str++);
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}
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void ssd1306_clear_display()
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{
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send_command(OLED_DISPLAY_OFF_CMD);// display off
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for (int j=0; j<8; j++) {
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ssd1306_set_position(0,j);
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for (int i=0; i<16; i++) //clear all columns
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ssd1306_putc(' ');
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}
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send_command(OLED_DISPLAY_ON_CMD); //display on
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ssd1306_set_position(0,0);
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}
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int ssd1306_init()
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{
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fd = open(I2C_BUS, O_RDWR);
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if (fd < 0) {
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printf("ERROR: unable to open i2c bus interface (%s)\n", I2C_BUS);
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return -1;
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}
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if (ioctl(fd, I2C_SLAVE, OLED_ADDR) < 0) {
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printf("ERROR: unable to access OLED as slave\n");
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return -1;
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}
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for (unsigned i=0; i<ARRAY_OF(init_commands); i++) {
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send_command (init_commands[i]);
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}
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ssd1306_clear_display();
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return 0;
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}
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