Note
This Bricklet is currently in the prototype stage and the software/hardware as well as the documentation is in an incomplete state.
This is the description of the C/C++ API bindings for the Accelerometer Bricklet. General information and technical specifications for the Accelerometer 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).
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 | #include <stdio.h>
#include "ip_connection.h"
#include "bricklet_accelerometer.h"
#define HOST "localhost"
#define PORT 4223
#define UID "sad" // Change to your UID
int main() {
// Create IP connection
IPConnection ipcon;
ipcon_create(&ipcon);
// Create device object
Accelerometer acc;
accelerometer_create(&acc, UID, &ipcon);
// Connect to brickd
if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
fprintf(stderr, "Could not connect\n");
exit(1);
}
// Don't use device before ipcon is connected
// Get current acceleration
int16_t x; int16_t y; int16_t z;
if(accelerometer_get_acceleration(&acc, &x, &y, &z) < 0) {
fprintf(stderr, "Could not get value, probably timeout\n");
exit(1);
}
printf("Acceleration(X): %fG\n", x/1000.0);
printf("Acceleration(Y): %fG\n", y/1000.0);
printf("Acceleration(Z): %fG\n", z/1000.0);
printf("\n");
printf("Press key to exit\n");
getchar();
ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
}
|
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 | #include <stdio.h>
#include "ip_connection.h"
#include "bricklet_accelerometer.h"
#define HOST "localhost"
#define PORT 4223
#define UID "sad" // Change to your UID
// Callback for acceleration
void cb_acceleration(int16_t x, int16_t y, int16_t z, void *user_data) {
(void)user_data; // avoid unused parameter warning
printf("Acceleration(X): %fG\n", x/1000.0);
printf("Acceleration(Y): %fG\n", y/1000.0);
printf("Acceleration(Z): %fG\n", z/1000.0);
printf("\n");
}
int main() {
// Create IP connection
IPConnection ipcon;
ipcon_create(&ipcon);
// Create device object
Accelerometer acc;
accelerometer_create(&acc, UID, &ipcon);
// Connect to brickd
if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
fprintf(stderr, "Could not connect\n");
exit(1);
}
// Don't use device before ipcon is connected
// Set Period for acceleration callback to 1s (1000ms)
// Note: The callback is only called every second if the
// acceleration has changed since the last call!
accelerometer_set_acceleration_callback_period(&acc, 1000);
// Register color callback to function cb_acceleration
accelerometer_register_callback(&acc,
ACCELEROMETER_CALLBACK_ACCELERATION,
(void *)cb_acceleration/1000.0,
NULL);
printf("Press key to exit\n");
getchar();
ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
}
|
Download (example_threshold.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 | #include <stdio.h>
#include "ip_connection.h"
#include "bricklet_accelerometer.h"
#define HOST "localhost"
#define PORT 4223
#define UID "sad" // Change to your UID
// Callback for acceleration threshold reached
void cb_reached(int16_t x, int16_t y, int16_t z, void *user_data) {
(void)user_data; // avoid unused parameter warning
printf("Acceleration(X): %fG\n", x/1000.0);
printf("Acceleration(Y): %fG\n", y/1000.0);
printf("Acceleration(Z): %fG\n", z/1000.0);
printf("\n");
}
int main() {
// Create IP connection
IPConnection ipcon;
ipcon_create(&ipcon);
// Create device object
Accelerometer acc;
accelerometer_create(&acc, UID, &ipcon);
// Connect to brickd
if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
fprintf(stderr, "Could not connect\n");
exit(1);
}
// Don't use device before ipcon is connected
// Get threshold callbacks with a debounce time of 10 seconds (10000ms)
accelerometer_set_debounce_period(&acc, 10000);
// Register threshold reached callback to function cb_reached
accelerometer_register_callback(&acc,
ACCELEROMETER_CALLBACK_ACCELERATION_REACHED,
(void *)cb_reached,
NULL);
// Configure threshold for acceleration values X, Y or Z greater than 2G
accelerometer_set_acceleration_callback_threshold(&acc, '>', 2000, 0, 2000, 0, 2000, 0);
printf("Press key to exit\n");
getchar();
ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
}
|
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:
as defined in ip_connection.h.
All functions listed below are thread-safe.
Creates the device object accelerometer with the unique device ID uid and adds it to the IPConnection ipcon:
Accelerometer accelerometer;
accelerometer_create(&accelerometer, "YOUR_DEVICE_UID", &ipcon);
This device object can be used after the IP connection has been connected (see examples above).
Removes the device object accelerometer from its IPConnection and destroys it. The device object cannot be used anymore afterwards.
Returns the acceleration in x, y and z direction. The values are given in mG (1/1000 G).
If you want to get the acceleration periodically, it is recommended to use the callback ACCELEROMETER_CALLBACK_ACCELERATION and set the period with accelerometer_set_acceleration_callback_period().
Returns the temperature of the accelerometer in °C.
Enables the LED on the Bricklet.
Disables the LED on the Bricklet.
Returns true if the LED is enabled, false otherwise.
Configures the data rate, full scale range and filter bandwidth. Possible values are:
Decreasing data rate or full scale range will also decrease the noise on the data.
The default values are 100Hz data rate, -4G to +4G range and 200Hz filter bandwidth.
The following defines are available for this function:
Returns the configuration as set by accelerometer_set_configuration().
The following defines are available for this function:
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.
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 accelerometer_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 accelerometer_set_response_expected() for the list of function ID defines available for this function.
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 and callbacks it is always disabled.
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:
Changes the response expected flag for all setter and callback configuration functions of this device at once.
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.
Registers a callback with ID id to the function callback. The user_data will be given as a parameter of the callback.
The available IDs with corresponding function signatures are listed below.
Sets the period in ms with which the ACCELEROMETER_CALLBACK_ACCELERATION callback is triggered periodically. A value of 0 turns the callback off.
ACCELEROMETER_CALLBACK_ACCELERATION is only triggered if the acceleration has changed since the last triggering.
The default value is 0.
Returns the period as set by accelerometer_set_acceleration_callback_period().
Sets the thresholds for the ACCELEROMETER_CALLBACK_ACCELERATION_REACHED callback.
The following options are possible:
Option | Description |
---|---|
'x' | Callback is turned off |
'o' | Callback is triggered when the temperature is outside the min and max values |
'i' | Callback is triggered when the temperature is inside the min and max values |
'<' | Callback is triggered when the temperature is smaller than the min value (max is ignored) |
'>' | Callback is triggered when the temperature is greater than the min value (max is ignored) |
The default value is ('x', 0, 0, 0, 0, 0, 0).
The following defines are available for this function:
Returns the threshold as set by accelerometer_set_acceleration_callback_threshold().
The following defines are available for this function:
Sets the period in ms with which the threshold callback
is triggered, if the threshold
keeps being reached.
The default value is 100.
Returns the debounce period as set by accelerometer_set_debounce_period().
Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the accelerometer_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); } accelerometer_register_callback(&accelerometer, ACCELEROMETER_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.
void callback(int16_t x, int16_t y, int16_t z, void *user_data)
This callback is triggered periodically with the period that is set by accelerometer_set_acceleration_callback_period(). The parameters are the X, Y and Z acceleration.
ACCELEROMETER_CALLBACK_ACCELERATION is only triggered if the acceleration has changed since the last triggering.
void callback(int16_t x, int16_t y, int16_t z, void *user_data)
This callback is triggered when the threshold as set by accelerometer_set_acceleration_callback_threshold() is reached. The parameters are the X, Y and Z acceleration.
If the threshold keeps being reached, the callback is triggered periodically with the period as set by accelerometer_set_debounce_period().
This constant is used to identify a Accelerometer Bricklet.
The accelerometer_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.