C/C++ - Ambient Light Bricklet 2.0

This is the description of the C/C++ API bindings for the Ambient Light Bricklet 2.0. General information and technical specifications for the Ambient Light Bricklet 2.0 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).

Simple

Download (example_simple.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_ambient_light_v2.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your Ambient Light Bricklet 2.0

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

    // Create device object
    AmbientLightV2 al;
    ambient_light_v2_create(&al, 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

    // Get current illuminance
    uint32_t illuminance;
    if(ambient_light_v2_get_illuminance(&al, &illuminance) < 0) {
        fprintf(stderr, "Could not get illuminance, probably timeout\n");
        return 1;
    }

    printf("Illuminance: %f lx\n", illuminance/100.0);

    printf("Press key to exit\n");
    getchar();
    ambient_light_v2_destroy(&al);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Callback

Download (example_callback.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
#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_ambient_light_v2.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your Ambient Light Bricklet 2.0

// Callback function for illuminance callback
void cb_illuminance(uint32_t illuminance, void *user_data) {
    (void)user_data; // avoid unused parameter warning

    printf("Illuminance: %f lx\n", illuminance/100.0);
}

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

    // Create device object
    AmbientLightV2 al;
    ambient_light_v2_create(&al, 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

    // Register illuminance callback to function cb_illuminance
    ambient_light_v2_register_callback(&al,
                                       AMBIENT_LIGHT_V2_CALLBACK_ILLUMINANCE,
                                       (void *)cb_illuminance,
                                       NULL);

    // Set period for illuminance callback to 1s (1000ms)
    // Note: The illuminance callback is only called every second
    //       if the illuminance has changed since the last call!
    ambient_light_v2_set_illuminance_callback_period(&al, 1000);

    printf("Press key to exit\n");
    getchar();
    ambient_light_v2_destroy(&al);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Threshold

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_ambient_light_v2.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your Ambient Light Bricklet 2.0

// Callback function for illuminance reached callback
void cb_illuminance_reached(uint32_t illuminance, void *user_data) {
    (void)user_data; // avoid unused parameter warning

    printf("Illuminance: %f lx\n", illuminance/100.0);
    printf("Too bright, close the curtains!\n");
}

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

    // Create device object
    AmbientLightV2 al;
    ambient_light_v2_create(&al, 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

    // Get threshold callbacks with a debounce time of 10 seconds (10000ms)
    ambient_light_v2_set_debounce_period(&al, 10000);

    // Register illuminance reached callback to function cb_illuminance_reached
    ambient_light_v2_register_callback(&al,
                                       AMBIENT_LIGHT_V2_CALLBACK_ILLUMINANCE_REACHED,
                                       (void *)cb_illuminance_reached,
                                       NULL);

    // Configure threshold for illuminance "greater than 500 lx"
    ambient_light_v2_set_illuminance_callback_threshold(&al, '>', 500*100, 0);

    printf("Press key to exit\n");
    getchar();
    ambient_light_v2_destroy(&al);
    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

as defined in ip_connection.h.

All functions listed below are thread-safe.

Basic Functions

void ambient_light_v2_create(AmbientLightV2 *ambient_light_v2, const char *uid, IPConnection *ipcon)

Creates the device object ambient_light_v2 with the unique device ID uid and adds it to the IPConnection ipcon:

AmbientLightV2 ambient_light_v2;
ambient_light_v2_create(&ambient_light_v2, "YOUR_DEVICE_UID", &ipcon);

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

void ambient_light_v2_destroy(AmbientLightV2 *ambient_light_v2)

Removes the device object ambient_light_v2 from its IPConnection and destroys it. The device object cannot be used anymore afterwards.

int ambient_light_v2_get_illuminance(AmbientLightV2 *ambient_light_v2, uint32_t *ret_illuminance)

Returns the illuminance of the ambient light sensor. The measurement range goes up to about 100000lux, but above 64000lux the precision starts to drop. The illuminance is given in lux/100, i.e. a value of 450000 means that an illuminance of 4500lux is measured.

Changed in version 2.0.2 (Plugin): An illuminance of 0lux indicates that the sensor is saturated and the configuration should be modified, see ambient_light_v2_set_configuration().

If you want to get the illuminance periodically, it is recommended to use the AMBIENT_LIGHT_V2_CALLBACK_ILLUMINANCE callback and set the period with ambient_light_v2_set_illuminance_callback_period().

Advanced Functions

int ambient_light_v2_set_configuration(AmbientLightV2 *ambient_light_v2, uint8_t illuminance_range, uint8_t integration_time)

Sets the configuration. It is possible to configure an illuminance range between 0-600lux and 0-64000lux and an integration time between 50ms and 400ms.

New in version 2.0.2 (Plugin): The unlimited illuminance range allows to measure up to about 100000lux, but above 64000lux the precision starts to drop.

A smaller illuminance range increases the resolution of the data. A longer integration time will result in less noise on the data.

Changed in version 2.0.2 (Plugin): If the actual measure illuminance is out-of-range then the current illuminance range maximum +0.01lux is reported by ambient_light_v2_get_illuminance() and the AMBIENT_LIGHT_V2_CALLBACK_ILLUMINANCE callback. For example, 800001 for the 0-8000lux range.

Changed in version 2.0.2 (Plugin): With a long integration time the sensor might be saturated before the measured value reaches the maximum of the selected illuminance range. In this case 0lux is reported by ambient_light_v2_get_illuminance() and the AMBIENT_LIGHT_V2_CALLBACK_ILLUMINANCE callback.

If the measurement is out-of-range or the sensor is saturated then you should configure the next higher illuminance range. If the highest range is already in use, then start to reduce the integration time.

The default values are 0-8000lux illuminance range and 200ms integration time.

The following defines are available for this function:

  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_UNLIMITED = 6
  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_64000LUX = 0
  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_32000LUX = 1
  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_16000LUX = 2
  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_8000LUX = 3
  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_1300LUX = 4
  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_600LUX = 5
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_50MS = 0
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_100MS = 1
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_150MS = 2
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_200MS = 3
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_250MS = 4
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_300MS = 5
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_350MS = 6
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_400MS = 7
int ambient_light_v2_get_configuration(AmbientLightV2 *ambient_light_v2, uint8_t *ret_illuminance_range, uint8_t *ret_integration_time)

Returns the configuration as set by ambient_light_v2_set_configuration().

The following defines are available for this function:

  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_UNLIMITED = 6
  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_64000LUX = 0
  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_32000LUX = 1
  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_16000LUX = 2
  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_8000LUX = 3
  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_1300LUX = 4
  • AMBIENT_LIGHT_V2_ILLUMINANCE_RANGE_600LUX = 5
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_50MS = 0
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_100MS = 1
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_150MS = 2
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_200MS = 3
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_250MS = 4
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_300MS = 5
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_350MS = 6
  • AMBIENT_LIGHT_V2_INTEGRATION_TIME_400MS = 7
int ambient_light_v2_get_api_version(AmbientLightV2 *ambient_light_v2, 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 ambient_light_v2_get_response_expected(AmbientLightV2 *ambient_light_v2, 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 ambient_light_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 send and errors are silently ignored, because they cannot be detected.

See ambient_light_v2_set_response_expected() for the list of function ID defines available for this function.

int ambient_light_v2_set_response_expected(AmbientLightV2 *ambient_light_v2, 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:

  • AMBIENT_LIGHT_V2_FUNCTION_SET_ILLUMINANCE_CALLBACK_PERIOD = 2
  • AMBIENT_LIGHT_V2_FUNCTION_SET_ILLUMINANCE_CALLBACK_THRESHOLD = 4
  • AMBIENT_LIGHT_V2_FUNCTION_SET_DEBOUNCE_PERIOD = 6
  • AMBIENT_LIGHT_V2_FUNCTION_SET_CONFIGURATION = 8
int ambient_light_v2_set_response_expected_all(AmbientLightV2 *ambient_light_v2, bool response_expected)

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

int ambient_light_v2_get_identity(AmbientLightV2 *ambient_light_v2, 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 ambient_light_v2_register_callback(AmbientLightV2 *ambient_light_v2, 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.

int ambient_light_v2_set_illuminance_callback_period(AmbientLightV2 *ambient_light_v2, uint32_t period)

Sets the period in ms with which the AMBIENT_LIGHT_V2_CALLBACK_ILLUMINANCE callback is triggered periodically. A value of 0 turns the callback off.

The AMBIENT_LIGHT_V2_CALLBACK_ILLUMINANCE callback is only triggered if the illuminance has changed since the last triggering.

The default value is 0.

int ambient_light_v2_get_illuminance_callback_period(AmbientLightV2 *ambient_light_v2, uint32_t *ret_period)

Returns the period as set by ambient_light_v2_set_illuminance_callback_period().

int ambient_light_v2_set_illuminance_callback_threshold(AmbientLightV2 *ambient_light_v2, char option, uint32_t min, uint32_t max)

Sets the thresholds for the AMBIENT_LIGHT_V2_CALLBACK_ILLUMINANCE_REACHED callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the illuminance is outside the min and max values
'i' Callback is triggered when the illuminance is inside the min and max values
'<' Callback is triggered when the illuminance is smaller than the min value (max is ignored)
'>' Callback is triggered when the illuminance is greater than the min value (max is ignored)

The default value is ('x', 0, 0).

The following defines are available for this function:

  • AMBIENT_LIGHT_V2_THRESHOLD_OPTION_OFF = 'x'
  • AMBIENT_LIGHT_V2_THRESHOLD_OPTION_OUTSIDE = 'o'
  • AMBIENT_LIGHT_V2_THRESHOLD_OPTION_INSIDE = 'i'
  • AMBIENT_LIGHT_V2_THRESHOLD_OPTION_SMALLER = '<'
  • AMBIENT_LIGHT_V2_THRESHOLD_OPTION_GREATER = '>'
int ambient_light_v2_get_illuminance_callback_threshold(AmbientLightV2 *ambient_light_v2, char *ret_option, uint32_t *ret_min, uint32_t *ret_max)

Returns the threshold as set by ambient_light_v2_set_illuminance_callback_threshold().

The following defines are available for this function:

  • AMBIENT_LIGHT_V2_THRESHOLD_OPTION_OFF = 'x'
  • AMBIENT_LIGHT_V2_THRESHOLD_OPTION_OUTSIDE = 'o'
  • AMBIENT_LIGHT_V2_THRESHOLD_OPTION_INSIDE = 'i'
  • AMBIENT_LIGHT_V2_THRESHOLD_OPTION_SMALLER = '<'
  • AMBIENT_LIGHT_V2_THRESHOLD_OPTION_GREATER = '>'
int ambient_light_v2_set_debounce_period(AmbientLightV2 *ambient_light_v2, uint32_t debounce)

Sets the period in ms with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

The default value is 100.

int ambient_light_v2_get_debounce_period(AmbientLightV2 *ambient_light_v2, uint32_t *ret_debounce)

Returns the debounce period as set by ambient_light_v2_set_debounce_period().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the ambient_light_v2_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);
}

ambient_light_v2_register_callback(&ambient_light_v2, AMBIENT_LIGHT_V2_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.

AMBIENT_LIGHT_V2_CALLBACK_ILLUMINANCE
void callback(uint32_t illuminance, void *user_data)

This callback is triggered periodically with the period that is set by ambient_light_v2_set_illuminance_callback_period(). The parameter is the illuminance of the ambient light sensor.

The AMBIENT_LIGHT_V2_CALLBACK_ILLUMINANCE callback is only triggered if the illuminance has changed since the last triggering.

AMBIENT_LIGHT_V2_CALLBACK_ILLUMINANCE_REACHED
void callback(uint32_t illuminance, void *user_data)

This callback is triggered when the threshold as set by ambient_light_v2_set_illuminance_callback_threshold() is reached. The parameter is the illuminance of the ambient light sensor.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by ambient_light_v2_set_debounce_period().

Constants

AMBIENT_LIGHT_V2_DEVICE_IDENTIFIER

This constant is used to identify a Ambient Light Bricklet 2.0.

The ambient_light_v2_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.

AMBIENT_LIGHT_V2_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Ambient Light Bricklet 2.0.