This is the description of the C/C++ for Microcontrollers API bindings for the Compass Bricklet. General information and technical specifications for the Compass Bricklet 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// This example is not self-contained.
2// It requires usage of the example driver specific to your platform.
3// See the HAL documentation.
4
5#include "src/bindings/hal_common.h"
6#include "src/bindings/bricklet_compass.h"
7
8void check(int rc, const char *msg);
9void example_setup(TF_HAL *hal);
10void example_loop(TF_HAL *hal);
11
12static TF_Compass c;
13
14void example_setup(TF_HAL *hal) {
15 // Create device object
16 check(tf_compass_create(&c, NULL, hal), "create device object");
17
18 // Get current heading
19 int16_t heading;
20 check(tf_compass_get_heading(&c, &heading), "get heading");
21
22 tf_hal_printf("Heading: %d 1/%d °\n", heading, 10);
23}
24
25void example_loop(TF_HAL *hal) {
26 // Poll for callbacks
27 tf_hal_callback_tick(hal, 0);
28}
1// This example is not self-contained.
2// It requires usage of the example driver specific to your platform.
3// See the HAL documentation.
4
5#include "src/bindings/hal_common.h"
6#include "src/bindings/bricklet_compass.h"
7
8void check(int rc, const char *msg);
9void example_setup(TF_HAL *hal);
10void example_loop(TF_HAL *hal);
11
12// Callback function for heading callback
13static void heading_handler(TF_Compass *device, int16_t heading, void *user_data) {
14 (void)device; (void)user_data; // avoid unused parameter warning
15
16 tf_hal_printf("Heading: %d 1/%d °\n", heading, 10);
17}
18
19static TF_Compass c;
20
21void example_setup(TF_HAL *hal) {
22 // Create device object
23 check(tf_compass_create(&c, NULL, hal), "create device object");
24
25 // Register heading callback to function heading_handler
26 tf_compass_register_heading_callback(&c,
27 heading_handler,
28 NULL);
29
30 // Set period for heading callback to 0.1s (100ms) without a threshold
31 tf_compass_set_heading_callback_configuration(&c, 100, false, 'x', 0, 0);
32}
33
34void example_loop(TF_HAL *hal) {
35 // Poll for callbacks
36 tf_hal_callback_tick(hal, 0);
37}
Most functions of the C/C++ bindings for microcontrollers return an error code
(e_code).
Possible error codes are:
TF_E\ _OK = 0
TF_E\ _TIMEOUT = -1
TF_E\ _INVALID_PARAMETER = -2
TF_E\ _NOT_SUPPORTED = -3
TF_E\ _UNKNOWN_ERROR_CODE = -4
TF_E\ _STREAM_OUT_OF_SYNC = -5
TF_E\ _INVALID_CHAR_IN_UID = -6
TF_E\ _UID_TOO_LONG = -7
TF_E\ _UID_OVERFLOW = -8
TF_E\ _TOO_MANY_DEVICES = -9
TF_E\ _DEVICE_NOT_FOUND = -10
TF_E\ _WRONG_DEVICE_TYPE = -11
TF_E\ _LOCKED = -12
TF_E\ _PORT_NOT_FOUND = -13
(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.
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Creates the device object compass with the optional unique device ID or port name
uid_or_port_name and adds it to the HAL hal:
TF_Compass compass;
tf_compass_create(&compass, NULL, &hal);
Normally uid_or_port_name can stay NULL. For more details about this
see section UID or Port Name.
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Removes the device object compass from its HAL and destroys it.
The device object cannot be used anymore afterwards.
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Returns the heading (north = 0 degree, east = 90 degree).
Alternatively you can use tf_compass_get_magnetic_flux_density() and calculate the
heading with heading = atan2(y, x) * 180 / PI.
If you want to get the value periodically, it is recommended to use the
Heading callback. You can set the callback configuration
with tf_compass_set_heading_callback_configuration().
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Returns the magnetic flux density (magnetic induction) for all three axis.
If you want to get the value periodically, it is recommended to use the
Magnetic Flux Density callback. You can set the callback configuration
with tf_compass_set_magnetic_flux_density_callback_configuration().
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Configures the data rate and background calibration.
Data Rate: Sets the data rate that is used by the magnetometer. The lower the data rate, the lower is the noise on the data.
Background Calibration: Set to true to enable the background calibration and false to turn it off. If the background calibration is enabled the sensing polarity is flipped once per second to automatically calculate and remove offset that is caused by temperature changes. This polarity flipping takes about 20ms. This means that once a second you will not get new data for a period of 20ms. We highly recommend that you keep the background calibration enabled and only disable it if the 20ms off-time is a problem in your application.
The following constants are available for this function:
For data_rate:
TF_COMPASS_DATA_RATE_100HZ = 0
TF_COMPASS_DATA_RATE_200HZ = 1
TF_COMPASS_DATA_RATE_400HZ = 2
TF_COMPASS_DATA_RATE_600HZ = 3
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Returns the configuration as set by tf_compass_set_configuration().
The following constants are available for this function:
For ret_data_rate:
TF_COMPASS_DATA_RATE_100HZ = 0
TF_COMPASS_DATA_RATE_200HZ = 1
TF_COMPASS_DATA_RATE_400HZ = 2
TF_COMPASS_DATA_RATE_600HZ = 3
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Sets offset and gain for each of the three axes.
The Bricklet is factory calibrated. If you want to re-calibrate the Bricklet we recommend that you do the calibration through Brick Viewer.
The calibration is saved in non-volatile memory and only has to be done once.
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Returns the calibration parameters as set by tf_compass_set_calibration().
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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.
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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:
TF_COMPASS_STATUS_LED_CONFIG_OFF = 0
TF_COMPASS_STATUS_LED_CONFIG_ON = 1
TF_COMPASS_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
TF_COMPASS_STATUS_LED_CONFIG_SHOW_STATUS = 3
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Returns the configuration as set by tf_compass_set_status_led_config()
The following constants are available for this function:
For ret_config:
TF_COMPASS_STATUS_LED_CONFIG_OFF = 0
TF_COMPASS_STATUS_LED_CONFIG_ON = 1
TF_COMPASS_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
TF_COMPASS_STATUS_LED_CONFIG_SHOW_STATUS = 3
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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.
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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!
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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.
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The period is the period with which the Heading callback is triggered
periodically. A value of 0 turns the callback off.
If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.
If it is set to false, the callback is continuously triggered with the period, independent of the value.
It is furthermore possible to constrain the callback with thresholds.
The option-parameter together with min/max sets a threshold for the Heading callback.
The following options are possible:
Option |
Description |
|---|---|
'x' |
Threshold is turned off |
'o' |
Threshold is triggered when the value is outside the min and max values |
'i' |
Threshold is triggered when the value is inside or equal to the min and max values |
'<' |
Threshold is triggered when the value is smaller than the min value (max is ignored) |
'>' |
Threshold is triggered when the value is greater than the min value (max is ignored) |
If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.
The following constants are available for this function:
For option:
TF_COMPASS_THRESHOLD_OPTION_OFF = 'x'
TF_COMPASS_THRESHOLD_OPTION_OUTSIDE = 'o'
TF_COMPASS_THRESHOLD_OPTION_INSIDE = 'i'
TF_COMPASS_THRESHOLD_OPTION_SMALLER = '<'
TF_COMPASS_THRESHOLD_OPTION_GREATER = '>'
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Returns the callback configuration as set by tf_compass_set_heading_callback_configuration().
The following constants are available for this function:
For ret_option:
TF_COMPASS_THRESHOLD_OPTION_OFF = 'x'
TF_COMPASS_THRESHOLD_OPTION_OUTSIDE = 'o'
TF_COMPASS_THRESHOLD_OPTION_INSIDE = 'i'
TF_COMPASS_THRESHOLD_OPTION_SMALLER = '<'
TF_COMPASS_THRESHOLD_OPTION_GREATER = '>'
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The period is the period with which the Magnetic Flux Density callback
is triggered periodically. A value of 0 turns the callback off.
If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.
If it is set to false, the callback is continuously triggered with the period, independent of the value.
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Returns the callback configuration as set by
tf_compass_set_magnetic_flux_density_callback_configuration().
Callbacks can be registered to receive time critical or recurring data from the
device. The registration is done with the corresponding tf_compass_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_compass_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_Compass *compass, int16_t heading, void *user_data)
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This callback is triggered periodically according to the configuration set by
tf_compass_set_heading_callback_configuration().
The parameter is the same as tf_compass_get_heading().
void handler(TF_Compass *compass, int32_t x, int32_t y, int32_t z, void *user_data)
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This callback is triggered periodically according to the configuration set by
tf_compass_set_magnetic_flux_density_callback_configuration().
The parameters are the same as tf_compass_get_magnetic_flux_density().
Virtual functions don't communicate with the device itself, but operate only on the API bindings device object.
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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_compass_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:
TF_COMPASS_FUNCTION_SET_HEADING_CALLBACK_CONFIGURATION = 2
TF_COMPASS_FUNCTION_SET_MAGNETIC_FLUX_DENSITY_CALLBACK_CONFIGURATION = 6
TF_COMPASS_FUNCTION_SET_CONFIGURATION = 9
TF_COMPASS_FUNCTION_SET_CALIBRATION = 11
TF_COMPASS_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
TF_COMPASS_FUNCTION_SET_STATUS_LED_CONFIG = 239
TF_COMPASS_FUNCTION_RESET = 243
TF_COMPASS_FUNCTION_WRITE_UID = 248
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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:
TF_COMPASS_FUNCTION_SET_HEADING_CALLBACK_CONFIGURATION = 2
TF_COMPASS_FUNCTION_SET_MAGNETIC_FLUX_DENSITY_CALLBACK_CONFIGURATION = 6
TF_COMPASS_FUNCTION_SET_CONFIGURATION = 9
TF_COMPASS_FUNCTION_SET_CALIBRATION = 11
TF_COMPASS_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
TF_COMPASS_FUNCTION_SET_STATUS_LED_CONFIG = 239
TF_COMPASS_FUNCTION_RESET = 243
TF_COMPASS_FUNCTION_WRITE_UID = 248
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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.
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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:
TF_COMPASS_BOOTLOADER_MODE_BOOTLOADER = 0
TF_COMPASS_BOOTLOADER_MODE_FIRMWARE = 1
TF_COMPASS_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
TF_COMPASS_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
TF_COMPASS_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
For ret_status:
TF_COMPASS_BOOTLOADER_STATUS_OK = 0
TF_COMPASS_BOOTLOADER_STATUS_INVALID_MODE = 1
TF_COMPASS_BOOTLOADER_STATUS_NO_CHANGE = 2
TF_COMPASS_BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
TF_COMPASS_BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
TF_COMPASS_BOOTLOADER_STATUS_CRC_MISMATCH = 5
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Returns the current bootloader mode, see tf_compass_set_bootloader_mode().
The following constants are available for this function:
For ret_mode:
TF_COMPASS_BOOTLOADER_MODE_BOOTLOADER = 0
TF_COMPASS_BOOTLOADER_MODE_FIRMWARE = 1
TF_COMPASS_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
TF_COMPASS_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
TF_COMPASS_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
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Sets the firmware pointer for tf_compass_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.
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Writes 64 Bytes of firmware at the position as written by
tf_compass_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.
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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.
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Returns the current UID as an integer. Encode as Base58 to get the usual string version.
This constant is used to identify a Compass Bricklet.
The functions tf_compass_get_identity() and tf_hal_get_device_info()
have a device_identifier output parameter to specify
the Brick's or Bricklet's type.
This constant represents the human readable name of a Compass Bricklet.