This is the description of the C/C++ for Microcontrollers API bindings for the Dual Button Bricklet 2.0. General information and technical specifications for the Dual Button Bricklet 2.0 are summarized in its hardware description.
An installation guide for the C/C++ for Microcontrollers API bindings is part of their general description.
The example code below is Public Domain (CC0 1.0).
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 | // This example is not self-contained.
// It requires usage of the example driver specific to your platform.
// See the HAL documentation.
#include "src/bindings/hal_common.h"
#include "src/bindings/bricklet_dual_button_v2.h"
void check(int rc, const char *msg);
void example_setup(TF_HAL *hal);
void example_loop(TF_HAL *hal);
// Callback function for state changed callback
static void state_changed_handler(TF_DualButtonV2 *device, uint8_t button_l,
uint8_t button_r, uint8_t led_l, uint8_t led_r,
void *user_data) {
(void)device; (void)led_l; (void)led_r; (void)user_data; // avoid unused parameter warning
if (button_l == TF_DUAL_BUTTON_V2_BUTTON_STATE_PRESSED) {
tf_hal_printf("Left Button: Pressed\n");
} else if (button_l == TF_DUAL_BUTTON_V2_BUTTON_STATE_RELEASED) {
tf_hal_printf("Left Button: Released\n");
}
if (button_r == TF_DUAL_BUTTON_V2_BUTTON_STATE_PRESSED) {
tf_hal_printf("Right Button: Pressed\n");
} else if (button_r == TF_DUAL_BUTTON_V2_BUTTON_STATE_RELEASED) {
tf_hal_printf("Right Button: Released\n");
}
tf_hal_printf("\n");
}
static TF_DualButtonV2 db;
void example_setup(TF_HAL *hal) {
// Create device object
check(tf_dual_button_v2_create(&db, NULL, hal), "create device object");
// Register state changed callback to function state_changed_handler
tf_dual_button_v2_register_state_changed_callback(&db,
state_changed_handler,
NULL);
// Enable state changed callback
check(tf_dual_button_v2_set_state_changed_callback_configuration(&db,
true), "call set_state_changed_callback_configuration");
}
void example_loop(TF_HAL *hal) {
// Poll for callbacks
tf_hal_callback_tick(hal, 0);
}
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Most functions of the C/C++ bindings for microcontrollers return an error code
(e_code
).
Possible error codes are:
(as defined in errors.h
) as well as the errors returned from
the hardware abstraction layer (HAL) that is used.
Use :cpp:func`tf_hal_strerror` (defined in the HAL's header file) to get an error string for an error code.
Data returned from the device, when a getter is called,
is handled via output parameters. These parameters are labeled with the
ret_
prefix. The bindings will not write to an output parameter if NULL or nullptr
is passed. This can be used to ignore outputs that you are not interested in.
None of the functions listed below are thread-safe. See the API bindings description for details.
Parameters: |
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Returns: |
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Creates the device object dual_button_v2
with the optional unique device ID or port name
uid_or_port_name
and adds it to the HAL hal
:
TF_DualButtonV2 dual_button_v2;
tf_dual_button_v2_create(&dual_button_v2, NULL, &hal);
Normally uid_or_port_name
can stay NULL
. For more details about this
see section UID or Port Name.
Parameters: |
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Returns: |
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Removes the device object dual_button_v2
from its HAL and destroys it.
The device object cannot be used anymore afterwards.
Parameters: |
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Returns: |
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Sets the state of the LEDs. Possible states are:
In auto toggle mode the LED is toggled automatically at each press of a button.
If you just want to set one of the LEDs and don't know the current state
of the other LED, you can get the state with tf_dual_button_v2_get_led_state()
or you
can use tf_dual_button_v2_set_selected_led_state()
.
The following constants are available for this function:
For led_l:
For led_r:
Parameters: |
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Output Parameters: |
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Returns: |
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Returns the current state of the LEDs, as set by tf_dual_button_v2_set_led_state()
.
The following constants are available for this function:
For ret_led_l:
For ret_led_r:
Parameters: |
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Output Parameters: |
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Returns: |
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Returns the current state for both buttons. Possible states are:
The following constants are available for this function:
For ret_button_l:
For ret_button_r:
Parameters: |
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Returns: |
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Sets the state of the selected LED.
The other LED remains untouched.
The following constants are available for this function:
For led:
For state:
Parameters: |
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Output Parameters: |
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Returns: |
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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.
Parameters: |
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Returns: |
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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:
Parameters: |
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Output Parameters: |
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Returns: |
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Returns the configuration as set by tf_dual_button_v2_set_status_led_config()
The following constants are available for this function:
For ret_config:
Parameters: |
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Output Parameters: |
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Returns: |
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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.
Parameters: |
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Returns: |
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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!
Parameters: |
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Output Parameters: |
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Returns: |
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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.
Parameters: |
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Returns: |
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If you enable this callback, the State Changed
callback is triggered
every time a button is pressed/released
Parameters: |
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Output Parameters: |
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Returns: |
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Returns the configuration as set by tf_dual_button_v2_set_state_changed_callback_configuration()
.
Callbacks can be registered to receive time critical or recurring data from the
device. The registration is done with the corresponding tf_dual_button_v2_register_*_callback
function.
The user_data
passed to the registration function as well as the device that triggered the callback are
passed to the registered callback handler.
Only one handler can be registered to a callback at the same time.
To deregister a callback, call the tf_dual_button_v2_register_*_callback
function
with NULL as handler.
Note
Using callbacks for recurring events is preferred compared to using getters. Polling for a callback requires writing one byte only. See here Optimizing Performance.
Warning
Calling bindings function from inside a callback handler is not allowed. See here Thread safety.
void handler(TF_DualButtonV2 *dual_button_v2, uint8_t button_l, uint8_t button_r, uint8_t led_l, uint8_t led_r, void *user_data)
Callback Parameters: |
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This callback is called whenever a button is pressed.
Possible states for buttons are:
Possible states for LEDs are:
This callback can be enabled with tf_dual_button_v2_set_state_changed_callback_configuration()
.
The following constants are available for this function:
For button_l:
For button_r:
For led_l:
For led_r:
Virtual functions don't communicate with the device itself, but operate only on the API bindings device object.
Parameters: |
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Output Parameters: |
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Returns: |
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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
tf_dual_button_v2_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:
Parameters: |
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Returns: |
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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:
Parameters: |
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Returns: |
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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.
Parameters: |
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Output Parameters: |
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Returns: |
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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:
Parameters: |
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Output Parameters: |
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Returns: |
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Returns the current bootloader mode, see tf_dual_button_v2_set_bootloader_mode()
.
The following constants are available for this function:
For ret_mode:
Parameters: |
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Returns: |
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Sets the firmware pointer for tf_dual_button_v2_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.
Parameters: |
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Output Parameters: |
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Returns: |
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Writes 64 Bytes of firmware at the position as written by
tf_dual_button_v2_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.
Parameters: |
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Returns: |
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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.
Parameters: |
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Output Parameters: |
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Returns: |
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Returns the current UID as an integer. Encode as Base58 to get the usual string version.
TF_DUAL_BUTTON_V2_DEVICE_IDENTIFIER
¶This constant is used to identify a Dual Button Bricklet 2.0.
The functions tf_dual_button_v2_get_identity()
and tf_hal_get_device_info()
have a device_identifier
output parameter to specify
the Brick's or Bricklet's type.
TF_DUAL_BUTTON_V2_DEVICE_DISPLAY_NAME
¶This constant represents the human readable name of a Dual Button Bricklet 2.0.