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adam-buckley/bouncing_dot.c

Created October 23, 2017 10:56
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  1. adam-buckley created this gist Oct 23, 2017.
    93 changes: 93 additions & 0 deletions bouncing_dot.c
    View file
    Original file line number Diff line number Diff line change
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    /**
    * A small demo of a dot bouncing inside a 128x64 OLED screen, using the Onion Omega 2. Note this isn't using the
    * OLED expansion, but a cheapo screen I bought from China, using the SSD1306 (as far as I could tell) driver.
    * This was only a personal exercise to see how easy it is to setup, it might be handly to someone else learning!
    *
    * To compile:
    * - install gcc and make (See: https://docs.onion.io/omega2-docs/c-compiler-on-omega.html)
    * - install git (Follow this: https://docs.onion.io/omega2-docs/installing-and-using-git.html)
    * - install python-dev
    * - git clone the i2c exp driver (https://github.com/OnionIoT/i2c-exp-driver)
    * - (At the time of writing) Alter the makefile according to this bug report (https://github.com/OnionIoT/i2c-exp-driver/issues/18)
    * - go into the "i2c-exp-driver" project and compile with `make`
    * - copy bin, include, lib directories to /usr
    * - compile gist below with `gcc bouncing_dot.c -loniondebug -lonioni2c -lonionoledexp`
    * - Run!
    *
    * @author Adam Buckley <[email protected]>
    */
    // #include <stdio.h>
    #include <unistd.h>
    #include <oled-exp.h>

    int main() {

    // Init the OLED
    int status = oledDriverInit();
    status |= oledSetDisplayPower(1);

    int x = 0, y = 0;
    int delta_x = 1, delta_y = 1;

    // Run forever
    while(1) {
    x += delta_x;
    y += delta_y;

    // When X hits a boundary on the OLED, flip the delta position
    if (x == 0 || x == 63) {
    delta_x *= -1;
    }

    // Do the same for the y coordinate
    if (y == 0 || y == 127) {
    delta_y *= -1;
    }

    // Set cursor to correct position
    // The way this works is that while the height of the OLED is 64px, there
    // is 8 logical rows, each with 8 addressable pixels. So the code below is just
    // working out where a pixel (e.g x = 57) should be placed

    // See https://docs.onion.io/omega2-docs/oled-expansion-c-library.html#understanding-the-display-1 for more info
    status |= oledSetCursorByPixel(((int) x / 8), y);
    switch(x % 8) {
    case 0:
    status |= oledWriteByte(0x01);
    break;
    case 1:
    status |= oledWriteByte(0x02);
    break;
    case 2:
    status |= oledWriteByte(0x04);
    break;
    case 3:
    status |= oledWriteByte(0x08);
    break;
    case 4:
    status |= oledWriteByte(0x10);
    break;
    case 5:
    status |= oledWriteByte(0x20);
    break;
    case 6:
    status |= oledWriteByte(0x40);
    break;
    case 7:
    status |= oledWriteByte(0x80);
    break;
    }

    // A larger usleep value will make the dot move slower
    usleep(10000);

    // Clear the current dot on the screen
    status |= oledSetCursorByPixel(((int) x / 8), y);
    status |= oledWriteByte(0x00);

    // Clear below for some reason will cause the screen to not print anything
    // status |= oledClear();
    }

    return 0;
    }