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.
The example code below is Public Domain (CC0 1.0).
Download (example_hello_world.c)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 | #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;
}
|
Download (example_load_image.c)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 | // 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;
}
|
Most functions of the C/C++ bindings return an error code (e_code
).
Data returned from the device, when a getter is called,
is handled via output parameters. These parameters are labeled with the
ret_
prefix.
Possible error codes are:
as defined in ip_connection.h
.
All functions listed below are thread-safe.
e_paper_296x128_create
(EPaper296x128 *e_paper_296x128, const char *uid, IPConnection *ipcon)¶Parameters: |
|
---|
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.
e_paper_296x128_destroy
(EPaper296x128 *e_paper_296x128)¶Parameters: |
|
---|
Removes the device object e_paper_296x128
from its IPConnection and destroys it.
The device object cannot be used anymore afterwards.
e_paper_296x128_draw
(EPaper296x128 *e_paper_296x128)¶Parameters: |
|
---|---|
Returns: |
|
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()
.
e_paper_296x128_get_draw_status
(EPaper296x128 *e_paper_296x128, uint8_t *ret_draw_status)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
Returns one of three draw statuses:
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 constants are available for this function:
For ret_draw_status:
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)¶Parameters: |
|
---|---|
Returns: |
|
Writes black/white pixels to the specified window into the buffer.
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.
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)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
Returns the current content of the black/white pixel buffer for the specified window.
The pixels are read into the window line by line top to bottom and each line is read 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.
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)¶Parameters: |
|
---|---|
Returns: |
|
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 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.
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)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
Returns the current content of the red or gray pixel buffer for the specified window.
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.
e_paper_296x128_fill_display
(EPaper296x128 *e_paper_296x128, uint8_t color)¶Parameters: |
|
---|---|
Returns: |
|
Fills the complete content of the display with the given color.
This function writes the pixels into the black/white/red|gray pixel buffer, to draw the buffer
to the display use e_paper_296x128_draw()
.
The following constants are available for this function:
For color:
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)¶Parameters: |
|
---|---|
Returns: |
|
Draws a text with up to 50 characters at the pixel position (x, y).
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.
This function writes the pixels into the black/white/red|gray pixel buffer, to draw the buffer
to the display use e_paper_296x128_draw()
.
The font conforms to code page 437.
The following constants are available for this function:
For font:
For color:
For orientation:
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)¶Parameters: |
|
---|---|
Returns: |
|
Draws a line from (x, y)-start to (x, y)-end in the given color.
This function writes the pixels into the black/white/red|gray pixel buffer, to draw the buffer
to the display use e_paper_296x128_draw()
.
The following constants are available for this function:
For color:
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)¶Parameters: |
|
---|---|
Returns: |
|
Draws a box from (x, y)-start to (x, y)-end in the given color.
If you set fill to true, the box will be filled with the color. Otherwise only the outline will be drawn.
This function writes the pixels into the black/white/red|gray pixel buffer, to draw the buffer
to the display use e_paper_296x128_draw()
.
The following constants are available for this function:
For color:
e_paper_296x128_set_update_mode
(EPaper296x128 *e_paper_296x128, uint8_t update_mode)¶Parameters: |
|
---|---|
Returns: |
|
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:
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 constants are available for this function:
For update_mode:
e_paper_296x128_get_update_mode
(EPaper296x128 *e_paper_296x128, uint8_t *ret_update_mode)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
Returns the update mode as set by e_paper_296x128_set_update_mode()
.
The following constants are available for this function:
For ret_update_mode:
e_paper_296x128_set_display_type
(EPaper296x128 *e_paper_296x128, uint8_t display_type)¶Parameters: |
|
---|---|
Returns: |
|
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 constants are available for this function:
For display_type:
e_paper_296x128_get_display_type
(EPaper296x128 *e_paper_296x128, uint8_t *ret_display_type)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
Returns the type of the e-paper display. It can either be black/white/red or black/white/gray.
The following constants are available for this function:
For ret_display_type:
e_paper_296x128_set_display_driver
(EPaper296x128 *e_paper_296x128, uint8_t display_driver)¶Parameters: |
|
---|---|
Returns: |
|
Sets the type of display driver. The Bricklet can currently support SSD1675A and SSD1680. 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 constants are available for this function:
For display_driver:
New in version 2.0.3 (Plugin).
e_paper_296x128_get_display_driver
(EPaper296x128 *e_paper_296x128, uint8_t *ret_display_driver)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
Returns the e-paper display driver.
The following constants are available for this function:
For ret_display_driver:
New in version 2.0.3 (Plugin).
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)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
Returns the error count for the communication between Brick and Bricklet.
The errors are divided into
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.
e_paper_296x128_set_status_led_config
(EPaper296x128 *e_paper_296x128, uint8_t config)¶Parameters: |
|
---|---|
Returns: |
|
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 constants are available for this function:
For config:
e_paper_296x128_get_status_led_config
(EPaper296x128 *e_paper_296x128, uint8_t *ret_config)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
Returns the configuration as set by e_paper_296x128_set_status_led_config()
The following constants are available for this function:
For ret_config:
e_paper_296x128_get_chip_temperature
(EPaper296x128 *e_paper_296x128, int16_t *ret_temperature)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
Returns the temperature 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.
e_paper_296x128_reset
(EPaper296x128 *e_paper_296x128)¶Parameters: |
|
---|---|
Returns: |
|
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!
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)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
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', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). A Bricklet connected to an Isolator Bricklet is always at position 'z'.
The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.
e_paper_296x128_register_callback
(EPaper296x128 *e_paper_296x128, int16_t callback_id, void (*function)(void), void *user_data)¶Parameters: |
|
---|
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 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:
void my_callback(int value, void *user_data) { printf("Value: %d\n", value); } e_paper_296x128_register_callback(&e_paper_296x128, E_PAPER_296X128_CALLBACK_EXAMPLE, (void (*)(void))my_callback, NULL);
The available constants with corresponding 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 Parameters: |
|
---|
Callback for the current draw status. Will be called every time the
draw status changes (see e_paper_296x128_get_draw_status()
).
The following constants are available for this function:
For draw_status:
Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.
e_paper_296x128_get_api_version
(EPaper296x128 *e_paper_296x128, uint8_t ret_api_version[3])¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
Returns the version of the API definition 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.
e_paper_296x128_get_response_expected
(EPaper296x128 *e_paper_296x128, uint8_t function_id, bool *ret_response_expected)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
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 sent and errors are silently ignored, because they cannot be detected.
The following constants are available for this function:
For function_id:
e_paper_296x128_set_response_expected
(EPaper296x128 *e_paper_296x128, uint8_t function_id, bool response_expected)¶Parameters: |
|
---|---|
Returns: |
|
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 sent and errors are silently ignored, because they cannot be detected.
The following constants are available for this function:
For function_id:
e_paper_296x128_set_response_expected_all
(EPaper296x128 *e_paper_296x128, bool response_expected)¶Parameters: |
|
---|---|
Returns: |
|
Changes the response expected flag for all setter and callback configuration functions of this device at once.
Internal functions are used for maintenance tasks such as flashing a new firmware of changing the UID of a Bricklet. These task should be performed using Brick Viewer instead of using the internal functions directly.
e_paper_296x128_set_bootloader_mode
(EPaper296x128 *e_paper_296x128, uint8_t mode, uint8_t *ret_status)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
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 constants are available for this function:
For mode:
For ret_status:
e_paper_296x128_get_bootloader_mode
(EPaper296x128 *e_paper_296x128, uint8_t *ret_mode)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
Returns the current bootloader mode, see e_paper_296x128_set_bootloader_mode()
.
The following constants are available for this function:
For ret_mode:
e_paper_296x128_set_write_firmware_pointer
(EPaper296x128 *e_paper_296x128, uint32_t pointer)¶Parameters: |
|
---|---|
Returns: |
|
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.
e_paper_296x128_write_firmware
(EPaper296x128 *e_paper_296x128, uint8_t data[64], uint8_t *ret_status)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
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.
e_paper_296x128_write_uid
(EPaper296x128 *e_paper_296x128, uint32_t uid)¶Parameters: |
|
---|---|
Returns: |
|
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.
e_paper_296x128_read_uid
(EPaper296x128 *e_paper_296x128, uint32_t *ret_uid)¶Parameters: |
|
---|---|
Output Parameters: |
|
Returns: |
|
Returns the current UID as an integer. Encode as Base58 to get the usual string version.
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.