C/C++ - E-Paper 296x128 Bricklet

This is the description of the C/C++ API bindings for the E-Paper 296x128 Bricklet. General information and technical specifications for the E-Paper 296x128 Bricklet are summarized in its hardware description.

An installation guide for the C/C++ API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Hello World

Download (example_hello_world.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_e_paper_296x128.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your E-Paper 296x128 Bricklet

int main(void) {
    // Create IP connection
    IPConnection ipcon;
    ipcon_create(&ipcon);

    // Create device object
    EPaper296x128 ep;
    e_paper_296x128_create(&ep, UID, &ipcon);

    // Connect to brickd
    if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
        fprintf(stderr, "Could not connect\n");
        return 1;
    }
    // Don't use device before ipcon is connected

    // Use black background
    e_paper_296x128_fill_display(&ep, E_PAPER_296X128_COLOR_BLACK);

    // Write big white "Hello World" in the middle of the screen
    e_paper_296x128_draw_text(&ep, 16, 48, E_PAPER_296X128_FONT_24X32,
                              E_PAPER_296X128_COLOR_WHITE,
                              E_PAPER_296X128_ORIENTATION_HORIZONTAL, "Hello World");
    e_paper_296x128_draw(&ep);

    printf("Press key to exit\n");
    getchar();
    e_paper_296x128_destroy(&ep);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Load Image

Download (example_load_image.c)

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// Tested with gcc:
// > gcc -pthread example_load_image.c ip_connection.c bricklet_e_paper_296x128.c -lgd -lm -o example

#include <stdio.h>
#include <math.h>
#include <gd.h> // https://libgd.github.io/

#include "ip_connection.h"
#include "bricklet_e_paper_296x128.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your E-Paper 296x128 Bricklet
#define WIDTH 296
#define HEIGHT 128

// Convert GD Image to matching color boolean array
void bool_array_from_image(gdImagePtr image, bool *pixels, uint8_t r, uint8_t g, uint8_t b) {
    int row, column, index;

    // Convert pixels into pages
    for (row = 0; row < HEIGHT; row++) {
        for (column = 0; column < WIDTH; column++) {
            index = gdImageGetPixel(image, column, row);
            pixels[row*WIDTH + column] = gdImageRed(image, index) == r && gdImageGreen(image, index) == g && gdImageBlue(image, index) == b;
        }
    }
}

int main(void) {
    // Create IP connection
    IPConnection ipcon;
    ipcon_create(&ipcon);

    // Create device object
    EPaper296x128 epaper;
    e_paper_296x128_create(&epaper, UID, &ipcon);

    // Connect to brickd
    if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
        fprintf(stderr, "Could not connect\n");
        return 1;
    }
    // Don't use device before ipcon is connected

    // Download example image here:
    // https://raw.githubusercontent.com/Tinkerforge/e-paper-296x128-bricklet/master/software/examples/tf_red.png
    FILE *file = fopen("tf_red.png", "rb");
    gdImagePtr image = gdImageCreateFromPng(file);
    
    bool pixels[HEIGHT * WIDTH];

    // Get black/white pixels from image and write them to the Bricklet buffer
    bool_array_from_image(image, pixels, 0xFF, 0xFF, 0xFF); 
    e_paper_296x128_write_black_white(&epaper, 0, 0, WIDTH-1, HEIGHT-1, pixels, HEIGHT*WIDTH);

    // Get red pixels from image and write them to the Bricklet buffer
    bool_array_from_image(image, pixels, 0xFF, 0, 0); 
    e_paper_296x128_write_color(&epaper, 0, 0, WIDTH-1, HEIGHT-1, pixels, HEIGHT*WIDTH);

    // Draw buffered values to the display
    e_paper_296x128_draw(&epaper);

    gdImageDestroy(image);

    printf("Press key to exit\n");
    getchar();
    e_paper_296x128_destroy(&epaper);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

API

Every function of the C/C++ bindings returns an integer which describes an error code. Data returned from the device, when a getter is called, is handled via call by reference. These parameters are labeled with the ret_ prefix.

Possible error codes are:

  • E_OK = 0
  • E_TIMEOUT = -1
  • E_NO_STREAM_SOCKET = -2
  • E_HOSTNAME_INVALID = -3
  • E_NO_CONNECT = -4
  • E_NO_THREAD = -5
  • E_NOT_ADDED = -6 (unused since bindings version 2.0.0)
  • E_ALREADY_CONNECTED = -7
  • E_NOT_CONNECTED = -8
  • E_INVALID_PARAMETER = -9
  • E_NOT_SUPPORTED = -10
  • E_UNKNOWN_ERROR_CODE = -11
  • E_STREAM_OUT_OF_SYNC = -12
  • E_INVALID_UID = -13

as defined in ip_connection.h.

All functions listed below are thread-safe.

Basic Functions

void e_paper_296x128_create(EPaper296x128 *e_paper_296x128, const char *uid, IPConnection *ipcon)

Creates the device object e_paper_296x128 with the unique device ID uid and adds it to the IPConnection ipcon:

EPaper296x128 e_paper_296x128;
e_paper_296x128_create(&e_paper_296x128, "YOUR_DEVICE_UID", &ipcon);

This device object can be used after the IP connection has been connected (see examples above).

void e_paper_296x128_destroy(EPaper296x128 *e_paper_296x128)

Removes the device object e_paper_296x128 from its IPConnection and destroys it. The device object cannot be used anymore afterwards.

int e_paper_296x128_draw(EPaper296x128 *e_paper_296x128)

Draws the current black/white and red or gray buffer to the e-paper display.

The Bricklet does not have any double-buffering. You should not call this function while writing to the buffer. See e_paper_296x128_get_draw_status().

int e_paper_296x128_get_draw_status(EPaper296x128 *e_paper_296x128, uint8_t *ret_draw_status)

Returns one of three draw statuses:

  • Idle
  • Copying: Data is being copied from the buffer of the Bricklet to the buffer of the display.
  • Drawing: The display is updating its content (during this phase the flickering etc happens).

You can write to the buffer (through one of the write or draw functions) when the status is either idle or drawing. You should not write to the buffer while it is being copied to the display. There is no double-buffering.

The following defines are available for this function:

  • E_PAPER_296X128_DRAW_STATUS_IDLE = 0
  • E_PAPER_296X128_DRAW_STATUS_COPYING = 1
  • E_PAPER_296X128_DRAW_STATUS_DRAWING = 2
int e_paper_296x128_write_black_white(EPaper296x128 *e_paper_296x128, uint16_t x_start, uint8_t y_start, uint16_t x_end, uint8_t y_end, bool *pixels, uint16_t pixels_length)

Writes black/white pixels to the specified window into the buffer.

The x-axis goes from 0 to 295 and the y-axis from 0 to 127. The pixels are written into the window line by line top to bottom and each line is written from left to right.

The value 0 (false) corresponds to a black pixel and the value 1 (true) to a white pixel.

This function writes the pixels into the black/white pixel buffer, to draw the buffer to the display use e_paper_296x128_draw().

Use e_paper_296x128_write_color() to write red or gray pixels.

int e_paper_296x128_read_black_white(EPaper296x128 *e_paper_296x128, uint16_t x_start, uint8_t y_start, uint16_t x_end, uint8_t y_end, bool *ret_pixels, uint16_t *ret_pixels_length)

Returns the current content of the black/white pixel buffer for the specified window.

The x-axis goes from 0 to 295 and the y-axis from 0 to 127. The pixels are written into the window line by line top to bottom and each line is written from left to right.

The current content of the buffer does not have to be the current content of the display. It is possible that the data was not drawn to the display yet and after a restart of the Bricklet the buffer will be reset to black, while the display retains its content.

int e_paper_296x128_write_color(EPaper296x128 *e_paper_296x128, uint16_t x_start, uint8_t y_start, uint16_t x_end, uint8_t y_end, bool *pixels, uint16_t pixels_length)

The E-Paper 296x128 Bricklet is available with the colors black/white/red and black/white/gray. Depending on the model this function writes either red or gray pixels to the specified window into the buffer.

The x-axis goes from 0 to 295 and the y-axis from 0 to 127. The pixels are written into the window line by line top to bottom and each line is written from left to right.

The value 0 (false) means that this pixel does not have color. It will be either black or white (see e_paper_296x128_write_black_white()). The value 1 (true) corresponds to a red or gray pixel, depending on the Bricklet model.

This function writes the pixels into the red or gray pixel buffer, to draw the buffer to the display use e_paper_296x128_draw().

Use e_paper_296x128_write_black_white() to write black/white pixels.

int e_paper_296x128_read_color(EPaper296x128 *e_paper_296x128, uint16_t x_start, uint8_t y_start, uint16_t x_end, uint8_t y_end, bool *ret_pixels, uint16_t *ret_pixels_length)

Returns the current content of the red or gray pixel buffer for the specified window.

The x-axis goes from 0 to 295 and the y-axis from 0 to 127. The pixels are written into the window line by line top to bottom and each line is written from left to right.

The current content of the buffer does not have to be the current content of the display. It is possible that the data was not drawn to the display yet and after a restart of the Bricklet the buffer will be reset to black, while the display retains its content.

int e_paper_296x128_fill_display(EPaper296x128 *e_paper_296x128, uint8_t color)

Fills the complete content of the display with the given color.

The following defines are available for this function:

  • E_PAPER_296X128_COLOR_BLACK = 0
  • E_PAPER_296X128_COLOR_WHITE = 1
  • E_PAPER_296X128_COLOR_RED = 2
  • E_PAPER_296X128_COLOR_GRAY = 2
int e_paper_296x128_draw_text(EPaper296x128 *e_paper_296x128, uint16_t position_x, uint8_t position_y, uint8_t font, uint8_t color, uint8_t orientation, const char text[50])

Draws a text with up to 50 characters at the pixel position (x, y).

The x values have to be within the range of 0 to 295 and the y values have to be within the range of 0 to 127.

You can use one of 9 different font sizes and draw the text in black/white/red|gray. The text can be drawn horizontal or vertical.

The following defines are available for this function:

  • E_PAPER_296X128_FONT_6X8 = 0
  • E_PAPER_296X128_FONT_6X16 = 1
  • E_PAPER_296X128_FONT_6X24 = 2
  • E_PAPER_296X128_FONT_6X32 = 3
  • E_PAPER_296X128_FONT_12X16 = 4
  • E_PAPER_296X128_FONT_12X24 = 5
  • E_PAPER_296X128_FONT_12X32 = 6
  • E_PAPER_296X128_FONT_18X24 = 7
  • E_PAPER_296X128_FONT_18X32 = 8
  • E_PAPER_296X128_FONT_24X32 = 9
  • E_PAPER_296X128_COLOR_BLACK = 0
  • E_PAPER_296X128_COLOR_WHITE = 1
  • E_PAPER_296X128_COLOR_RED = 2
  • E_PAPER_296X128_COLOR_GRAY = 2
  • E_PAPER_296X128_ORIENTATION_HORIZONTAL = 0
  • E_PAPER_296X128_ORIENTATION_VERTICAL = 1
int e_paper_296x128_draw_line(EPaper296x128 *e_paper_296x128, uint16_t position_x_start, uint8_t position_y_start, uint16_t position_x_end, uint8_t position_y_end, uint8_t color)

Draws a line from (x, y)-start to (x, y)-end in the given color. The x values have to be within the range of 0 to 295 and the y values have t be within the range of 0 to 127.

The following defines are available for this function:

  • E_PAPER_296X128_COLOR_BLACK = 0
  • E_PAPER_296X128_COLOR_WHITE = 1
  • E_PAPER_296X128_COLOR_RED = 2
  • E_PAPER_296X128_COLOR_GRAY = 2
int e_paper_296x128_draw_box(EPaper296x128 *e_paper_296x128, uint16_t position_x_start, uint8_t position_y_start, uint16_t position_x_end, uint8_t position_y_end, bool fill, uint8_t color)

Draws a box from (x, y)-start to (x, y)-end in the given color. The x values have to be within the range of 0 to 295 and the y values have to be within the range of 0 to 127.

If you set fill to true, the box will be filled with the color. Otherwise only the outline will be drawn.

The following defines are available for this function:

  • E_PAPER_296X128_COLOR_BLACK = 0
  • E_PAPER_296X128_COLOR_WHITE = 1
  • E_PAPER_296X128_COLOR_RED = 2
  • E_PAPER_296X128_COLOR_GRAY = 2

Advanced Functions

int e_paper_296x128_set_update_mode(EPaper296x128 *e_paper_296x128, uint8_t update_mode)

Note

The default update mode corresponds to the default e-paper display manufacturer settings. All of the other modes are experimental and will result in increased ghosting and possibly other long-term side effects.

If you want to know more about the inner workings of an e-paper display take a look at this excellent video from Ben Krasnow: https://www.youtube.com/watch?v=MsbiO8EAsGw.

If you are not sure about this option, leave the update mode at default.

Currently there are three update modes available:

  • Default: Settings as given by the manufacturer. An update will take about 7.5 seconds and during the update the screen will flicker several times.
  • Black/White: This will only update the black/white pixel. It uses the manufacturer settings for black/white and ignores the red or gray pixel buffer. With this mode the display will flicker once and it takes about 2.5 seconds. Compared to the default settings there is more ghosting.
  • Delta: This will only update the black/white pixel. It uses an aggressive method where the changes are not applied for a whole buffer but only for the delta between the last and the next buffer. With this mode the display will not flicker during an update and it takes about 900-950ms. Compared to the other two settings there is more ghosting. This mode can be used for something like a flicker-free live update of a text.

With the black/white/red display if you use either the black/white or the delta mode, after a while of going back and forth between black and white the white color will start to appear red-ish or pink-ish.

If you use the aggressive delta mode and rapidly change the content, we recommend that you change back to the default mode every few hours and in the default mode cycle between the three available colors a few times. This will get rid of the ghosting and after that you can go back to the delta mode with flicker-free updates.

The following defines are available for this function:

  • E_PAPER_296X128_UPDATE_MODE_DEFAULT = 0
  • E_PAPER_296X128_UPDATE_MODE_BLACK_WHITE = 1
  • E_PAPER_296X128_UPDATE_MODE_DELTA = 2
int e_paper_296x128_get_update_mode(EPaper296x128 *e_paper_296x128, uint8_t *ret_update_mode)

Returns the update mode as set by e_paper_296x128_set_update_mode().

The following defines are available for this function:

  • E_PAPER_296X128_UPDATE_MODE_DEFAULT = 0
  • E_PAPER_296X128_UPDATE_MODE_BLACK_WHITE = 1
  • E_PAPER_296X128_UPDATE_MODE_DELTA = 2
int e_paper_296x128_set_display_type(EPaper296x128 *e_paper_296x128, uint8_t display_type)

Sets the type of the display. The e-paper display is available in black/white/red and black/white/gray. This will be factory set during the flashing and testing phase. The value is saved in non-volatile memory and will stay after a power cycle.

The following defines are available for this function:

  • E_PAPER_296X128_DISPLAY_TYPE_BLACK_WHITE_RED = 0
  • E_PAPER_296X128_DISPLAY_TYPE_BLACK_WHITE_GRAY = 1
int e_paper_296x128_get_display_type(EPaper296x128 *e_paper_296x128, uint8_t *ret_display_type)

Returns the type of the e-paper display. It can either be black/white/red or black/white/gray.

The following defines are available for this function:

  • E_PAPER_296X128_DISPLAY_TYPE_BLACK_WHITE_RED = 0
  • E_PAPER_296X128_DISPLAY_TYPE_BLACK_WHITE_GRAY = 1
int e_paper_296x128_get_api_version(EPaper296x128 *e_paper_296x128, uint8_t ret_api_version[3])

Returns the version of the API definition (major, minor, revision) implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

int e_paper_296x128_get_response_expected(EPaper296x128 *e_paper_296x128, uint8_t function_id, bool *ret_response_expected)

Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For callback configuration functions it is enabled by default too, but can be disabled by e_paper_296x128_set_response_expected(). For setter functions it is disabled by default and can be enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

See e_paper_296x128_set_response_expected() for the list of function ID defines available for this function.

int e_paper_296x128_set_response_expected(EPaper296x128 *e_paper_296x128, uint8_t function_id, bool response_expected)

Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and callback configuration functions (default value: true). For getter functions it is always enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following function ID defines are available for this function:

  • E_PAPER_296X128_FUNCTION_DRAW = 1
  • E_PAPER_296X128_FUNCTION_WRITE_BLACK_WHITE = 3
  • E_PAPER_296X128_FUNCTION_WRITE_COLOR = 5
  • E_PAPER_296X128_FUNCTION_FILL_DISPLAY = 7
  • E_PAPER_296X128_FUNCTION_DRAW_TEXT = 8
  • E_PAPER_296X128_FUNCTION_DRAW_LINE = 9
  • E_PAPER_296X128_FUNCTION_DRAW_BOX = 10
  • E_PAPER_296X128_FUNCTION_SET_UPDATE_MODE = 12
  • E_PAPER_296X128_FUNCTION_SET_DISPLAY_TYPE = 14
  • E_PAPER_296X128_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • E_PAPER_296X128_FUNCTION_SET_STATUS_LED_CONFIG = 239
  • E_PAPER_296X128_FUNCTION_RESET = 243
  • E_PAPER_296X128_FUNCTION_WRITE_UID = 248
int e_paper_296x128_set_response_expected_all(EPaper296x128 *e_paper_296x128, bool response_expected)

Changes the response expected flag for all setter and callback configuration functions of this device at once.

int e_paper_296x128_get_spitfp_error_count(EPaper296x128 *e_paper_296x128, uint32_t *ret_error_count_ack_checksum, uint32_t *ret_error_count_message_checksum, uint32_t *ret_error_count_frame, uint32_t *ret_error_count_overflow)

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

int e_paper_296x128_set_bootloader_mode(EPaper296x128 *e_paper_296x128, uint8_t mode, uint8_t *ret_status)

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following defines are available for this function:

  • E_PAPER_296X128_BOOTLOADER_MODE_BOOTLOADER = 0
  • E_PAPER_296X128_BOOTLOADER_MODE_FIRMWARE = 1
  • E_PAPER_296X128_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • E_PAPER_296X128_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • E_PAPER_296X128_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • E_PAPER_296X128_BOOTLOADER_STATUS_OK = 0
  • E_PAPER_296X128_BOOTLOADER_STATUS_INVALID_MODE = 1
  • E_PAPER_296X128_BOOTLOADER_STATUS_NO_CHANGE = 2
  • E_PAPER_296X128_BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • E_PAPER_296X128_BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • E_PAPER_296X128_BOOTLOADER_STATUS_CRC_MISMATCH = 5
int e_paper_296x128_get_bootloader_mode(EPaper296x128 *e_paper_296x128, uint8_t *ret_mode)

Returns the current bootloader mode, see e_paper_296x128_set_bootloader_mode().

The following defines are available for this function:

  • E_PAPER_296X128_BOOTLOADER_MODE_BOOTLOADER = 0
  • E_PAPER_296X128_BOOTLOADER_MODE_FIRMWARE = 1
  • E_PAPER_296X128_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • E_PAPER_296X128_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • E_PAPER_296X128_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
int e_paper_296x128_set_write_firmware_pointer(EPaper296x128 *e_paper_296x128, uint32_t pointer)

Sets the firmware pointer for e_paper_296x128_write_firmware(). The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

int e_paper_296x128_write_firmware(EPaper296x128 *e_paper_296x128, uint8_t data[64], uint8_t *ret_status)

Writes 64 Bytes of firmware at the position as written by e_paper_296x128_set_write_firmware_pointer() before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

int e_paper_296x128_set_status_led_config(EPaper296x128 *e_paper_296x128, uint8_t config)

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following defines are available for this function:

  • E_PAPER_296X128_STATUS_LED_CONFIG_OFF = 0
  • E_PAPER_296X128_STATUS_LED_CONFIG_ON = 1
  • E_PAPER_296X128_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • E_PAPER_296X128_STATUS_LED_CONFIG_SHOW_STATUS = 3
int e_paper_296x128_get_status_led_config(EPaper296x128 *e_paper_296x128, uint8_t *ret_config)

Returns the configuration as set by e_paper_296x128_set_status_led_config()

The following defines are available for this function:

  • E_PAPER_296X128_STATUS_LED_CONFIG_OFF = 0
  • E_PAPER_296X128_STATUS_LED_CONFIG_ON = 1
  • E_PAPER_296X128_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • E_PAPER_296X128_STATUS_LED_CONFIG_SHOW_STATUS = 3
int e_paper_296x128_get_chip_temperature(EPaper296x128 *e_paper_296x128, int16_t *ret_temperature)

Returns the temperature in °C as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

int e_paper_296x128_reset(EPaper296x128 *e_paper_296x128)

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

int e_paper_296x128_write_uid(EPaper296x128 *e_paper_296x128, uint32_t uid)

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

int e_paper_296x128_read_uid(EPaper296x128 *e_paper_296x128, uint32_t *ret_uid)

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

int e_paper_296x128_get_identity(EPaper296x128 *e_paper_296x128, char ret_uid[8], char ret_connected_uid[8], char *ret_position, uint8_t ret_hardware_version[3], uint8_t ret_firmware_version[3], uint16_t *ret_device_identifier)

Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be 'a', 'b', 'c' or 'd'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.

Callback Configuration Functions

void e_paper_296x128_register_callback(EPaper296x128 *e_paper_296x128, int16_t callback_id, void *function, void *user_data)

Registers the given function with the given callback_id. The user_data will be passed as the last parameter to the function.

The available callback IDs with corresponding function signatures are listed below.

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the e_paper_296x128_register_callback() function. The parameters consist of the device object, the callback ID, the callback function and optional user data:

void my_callback(int p, void *user_data) {
    printf("parameter: %d\n", p);
}

e_paper_296x128_register_callback(&e_paper_296x128, E_PAPER_296X128_CALLBACK_EXAMPLE, (void *)my_callback, NULL);

The available constants with corresponding callback function signatures are described below.

Note

Using callbacks for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.

E_PAPER_296X128_CALLBACK_DRAW_STATUS
void callback(uint8_t draw_status, void *user_data)

Callback for the current draw status. Will be called every time the draw status changes (see e_paper_296x128_get_draw_status()).

The following defines are available for this function:

  • E_PAPER_296X128_DRAW_STATUS_IDLE = 0
  • E_PAPER_296X128_DRAW_STATUS_COPYING = 1
  • E_PAPER_296X128_DRAW_STATUS_DRAWING = 2

Constants

E_PAPER_296X128_DEVICE_IDENTIFIER

This constant is used to identify a E-Paper 296x128 Bricklet.

The e_paper_296x128_get_identity() function and the IPCON_CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

E_PAPER_296X128_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a E-Paper 296x128 Bricklet.