C/C++ - Current12 Bricklet

This is the description of the C/C++ API bindings for the Current12 Bricklet. General information and technical specifications for the Current12 Bricklet 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)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_current12.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your Current12 Bricklet

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

    // Create device object
    Current12 c;
    current12_create(&c, 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 current
    int16_t current;
    if(current12_get_current(&c, &current) < 0) {
        fprintf(stderr, "Could not get current, probably timeout\n");
        return 1;
    }

    printf("Current: %f A\n", current/1000.0);

    printf("Press key to exit\n");
    getchar();
    current12_destroy(&c);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Callback

Download (example_callback.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_current12.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your Current12 Bricklet

// Callback function for current callback
void cb_current(int16_t current, void *user_data) {
    (void)user_data; // avoid unused parameter warning

    printf("Current: %f A\n", current/1000.0);
}

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

    // Create device object
    Current12 c;
    current12_create(&c, 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 current callback to function cb_current
    current12_register_callback(&c,
                                CURRENT12_CALLBACK_CURRENT,
                                (void (*)(void))cb_current,
                                NULL);

    // Set period for current callback to 1s (1000ms)
    // Note: The current callback is only called every second
    //       if the current has changed since the last call!
    current12_set_current_callback_period(&c, 1000);

    printf("Press key to exit\n");
    getchar();
    current12_destroy(&c);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Threshold

Download (example_threshold.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_current12.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your Current12 Bricklet

// Callback function for current reached callback
void cb_current_reached(int16_t current, void *user_data) {
    (void)user_data; // avoid unused parameter warning

    printf("Current: %f A\n", current/1000.0);
}

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

    // Create device object
    Current12 c;
    current12_create(&c, 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)
    current12_set_debounce_period(&c, 10000);

    // Register current reached callback to function cb_current_reached
    current12_register_callback(&c,
                                CURRENT12_CALLBACK_CURRENT_REACHED,
                                (void (*)(void))cb_current_reached,
                                NULL);

    // Configure threshold for current "greater than 5 A"
    current12_set_current_callback_threshold(&c, '>', 5*1000, 0);

    printf("Press key to exit\n");
    getchar();
    current12_destroy(&c);
    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 output parameters. 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 C/C++ 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
  • E_INVALID_UID = -13
  • E_NON_ASCII_CHAR_IN_SECRET = -14

as defined in ip_connection.h.

All functions listed below are thread-safe.

Basic Functions

void current12_create(Current12 *current12, const char *uid, IPConnection *ipcon)
Parameters:
  • current12 – Type: Current12 *
  • uid – Type: const char *
  • ipcon – Type: IPConnection *

Creates the device object current12 with the unique device ID uid and adds it to the IPConnection ipcon:

Current12 current12;
current12_create(&current12, "YOUR_DEVICE_UID", &ipcon);

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

void current12_destroy(Current12 *current12)
Parameters:
  • current12 – Type: Current12 *

Removes the device object current12 from its IPConnection and destroys it. The device object cannot be used anymore afterwards.

int current12_get_current(Current12 *current12, int16_t *ret_current)
Parameters:
  • current12 – Type: Current12 *
Output Parameters:
  • ret_current – Type: int16_t, Unit: 1 mA, Range: [-12500 to 12500]
Returns:
  • error_code – Type: int

Returns the current of the sensor.

If you want to get the current periodically, it is recommended to use the CURRENT12_CALLBACK_CURRENT callback and set the period with current12_set_current_callback_period().

Advanced Functions

int current12_calibrate(Current12 *current12)
Parameters:
  • current12 – Type: Current12 *
Returns:
  • error_code – Type: int

Calibrates the 0 value of the sensor. You have to call this function when there is no current present.

The zero point of the current sensor is depending on the exact properties of the analog-to-digital converter, the length of the Bricklet cable and the temperature. Thus, if you change the Brick or the environment in which the Bricklet is used, you might have to recalibrate.

The resulting calibration will be saved on the EEPROM of the Current Bricklet.

int current12_is_over_current(Current12 *current12, bool *ret_over)
Parameters:
  • current12 – Type: Current12 *
Output Parameters:
  • ret_over – Type: bool
Returns:
  • error_code – Type: int

Returns true if more than 12.5A were measured.

Note

To reset this value you have to power cycle the Bricklet.

int current12_get_analog_value(Current12 *current12, uint16_t *ret_value)
Parameters:
  • current12 – Type: Current12 *
Output Parameters:
  • ret_value – Type: uint16_t, Range: [0 to 4095]
Returns:
  • error_code – Type: int

Returns the value as read by a 12-bit analog-to-digital converter.

Note

The value returned by current12_get_current() is averaged over several samples to yield less noise, while current12_get_analog_value() gives back raw unfiltered analog values. The only reason to use current12_get_analog_value() is, if you need the full resolution of the analog-to-digital converter.

If you want the analog value periodically, it is recommended to use the CURRENT12_CALLBACK_ANALOG_VALUE callback and set the period with current12_set_analog_value_callback_period().

int current12_get_identity(Current12 *current12, 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:
  • current12 – Type: Current12 *
Output Parameters:
  • ret_uid – Type: char[8]
  • ret_connected_uid – Type: char[8]
  • ret_position – Type: char, Range: ['a' to 'h', 'i', 'z']
  • ret_hardware_version – Type: uint8_t[3]
    • 0: major – Type: uint8_t, Range: [0 to 255]
    • 1: minor – Type: uint8_t, Range: [0 to 255]
    • 2: revision – Type: uint8_t, Range: [0 to 255]
  • ret_firmware_version – Type: uint8_t[3]
    • 0: major – Type: uint8_t, Range: [0 to 255]
    • 1: minor – Type: uint8_t, Range: [0 to 255]
    • 2: revision – Type: uint8_t, Range: [0 to 255]
  • ret_device_identifier – Type: uint16_t, Range: [0 to 216 - 1]
Returns:
  • error_code – Type: int

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). The Raspberry Pi HAT (Zero) Brick is always at position 'i' and the Bricklet connected to an Isolator Bricklet is always as position 'z'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.

Callback Configuration Functions

void current12_register_callback(Current12 *current12, int16_t callback_id, void (*function)(void), void *user_data)
Parameters:
  • current12 – Type: Current12 *
  • callback_id – Type: int16_t
  • function – Type: void (*)(void)
  • user_data – Type: void *

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 current12_set_current_callback_period(Current12 *current12, uint32_t period)
Parameters:
  • current12 – Type: Current12 *
  • period – Type: uint32_t, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • error_code – Type: int

Sets the period with which the CURRENT12_CALLBACK_CURRENT callback is triggered periodically. A value of 0 turns the callback off.

The CURRENT12_CALLBACK_CURRENT callback is only triggered if the current has changed since the last triggering.

int current12_get_current_callback_period(Current12 *current12, uint32_t *ret_period)
Parameters:
  • current12 – Type: Current12 *
Output Parameters:
  • ret_period – Type: uint32_t, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • error_code – Type: int

Returns the period as set by current12_set_current_callback_period().

int current12_set_analog_value_callback_period(Current12 *current12, uint32_t period)
Parameters:
  • current12 – Type: Current12 *
  • period – Type: uint32_t, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • error_code – Type: int

Sets the period with which the CURRENT12_CALLBACK_ANALOG_VALUE callback is triggered periodically. A value of 0 turns the callback off.

The CURRENT12_CALLBACK_ANALOG_VALUE callback is only triggered if the analog value has changed since the last triggering.

int current12_get_analog_value_callback_period(Current12 *current12, uint32_t *ret_period)
Parameters:
  • current12 – Type: Current12 *
Output Parameters:
  • ret_period – Type: uint32_t, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • error_code – Type: int

Returns the period as set by current12_set_analog_value_callback_period().

int current12_set_current_callback_threshold(Current12 *current12, char option, int16_t min, int16_t max)
Parameters:
  • current12 – Type: Current12 *
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: int16_t, Unit: 1 mA, Range: [-215 to 215 - 1], Default: 0
  • max – Type: int16_t, Unit: 1 mA, Range: [-215 to 215 - 1], Default: 0
Returns:
  • error_code – Type: int

Sets the thresholds for the CURRENT12_CALLBACK_CURRENT_REACHED callback.

The following options are possible:

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

The following constants are available for this function:

For option:

  • CURRENT12_THRESHOLD_OPTION_OFF = 'x'
  • CURRENT12_THRESHOLD_OPTION_OUTSIDE = 'o'
  • CURRENT12_THRESHOLD_OPTION_INSIDE = 'i'
  • CURRENT12_THRESHOLD_OPTION_SMALLER = '<'
  • CURRENT12_THRESHOLD_OPTION_GREATER = '>'
int current12_get_current_callback_threshold(Current12 *current12, char *ret_option, int16_t *ret_min, int16_t *ret_max)
Parameters:
  • current12 – Type: Current12 *
Output Parameters:
  • ret_option – Type: char, Range: See constants, Default: 'x'
  • ret_min – Type: int16_t, Unit: 1 mA, Range: [-215 to 215 - 1], Default: 0
  • ret_max – Type: int16_t, Unit: 1 mA, Range: [-215 to 215 - 1], Default: 0
Returns:
  • error_code – Type: int

Returns the threshold as set by current12_set_current_callback_threshold().

The following constants are available for this function:

For ret_option:

  • CURRENT12_THRESHOLD_OPTION_OFF = 'x'
  • CURRENT12_THRESHOLD_OPTION_OUTSIDE = 'o'
  • CURRENT12_THRESHOLD_OPTION_INSIDE = 'i'
  • CURRENT12_THRESHOLD_OPTION_SMALLER = '<'
  • CURRENT12_THRESHOLD_OPTION_GREATER = '>'
int current12_set_analog_value_callback_threshold(Current12 *current12, char option, uint16_t min, uint16_t max)
Parameters:
  • current12 – Type: Current12 *
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: uint16_t, Range: [0 to 216 - 1], Default: 0
  • max – Type: uint16_t, Range: [0 to 216 - 1], Default: 0
Returns:
  • error_code – Type: int

Sets the thresholds for the CURRENT12_CALLBACK_ANALOG_VALUE_REACHED callback.

The following options are possible:

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

The following constants are available for this function:

For option:

  • CURRENT12_THRESHOLD_OPTION_OFF = 'x'
  • CURRENT12_THRESHOLD_OPTION_OUTSIDE = 'o'
  • CURRENT12_THRESHOLD_OPTION_INSIDE = 'i'
  • CURRENT12_THRESHOLD_OPTION_SMALLER = '<'
  • CURRENT12_THRESHOLD_OPTION_GREATER = '>'
int current12_get_analog_value_callback_threshold(Current12 *current12, char *ret_option, uint16_t *ret_min, uint16_t *ret_max)
Parameters:
  • current12 – Type: Current12 *
Output Parameters:
  • ret_option – Type: char, Range: See constants, Default: 'x'
  • ret_min – Type: uint16_t, Range: [0 to 216 - 1], Default: 0
  • ret_max – Type: uint16_t, Range: [0 to 216 - 1], Default: 0
Returns:
  • error_code – Type: int

Returns the threshold as set by current12_set_analog_value_callback_threshold().

The following constants are available for this function:

For ret_option:

  • CURRENT12_THRESHOLD_OPTION_OFF = 'x'
  • CURRENT12_THRESHOLD_OPTION_OUTSIDE = 'o'
  • CURRENT12_THRESHOLD_OPTION_INSIDE = 'i'
  • CURRENT12_THRESHOLD_OPTION_SMALLER = '<'
  • CURRENT12_THRESHOLD_OPTION_GREATER = '>'
int current12_set_debounce_period(Current12 *current12, uint32_t debounce)
Parameters:
  • current12 – Type: Current12 *
  • debounce – Type: uint32_t, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100
Returns:
  • error_code – Type: int

Sets the period with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

int current12_get_debounce_period(Current12 *current12, uint32_t *ret_debounce)
Parameters:
  • current12 – Type: Current12 *
Output Parameters:
  • ret_debounce – Type: uint32_t, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100
Returns:
  • error_code – Type: int

Returns the debounce period as set by current12_set_debounce_period().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the current12_register_callback() function:

void my_callback(int value, void *user_data) {
    printf("Value: %d\n", value);
}

current12_register_callback(&current12,
                            CURRENT12_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.

CURRENT12_CALLBACK_CURRENT
void callback(int16_t current, void *user_data)
Callback Parameters:
  • current – Type: int16_t, Unit: 1 mA, Range: [-12500 to 12500]
  • user_data – Type: void *

This callback is triggered periodically with the period that is set by current12_set_current_callback_period(). The parameter is the current of the sensor.

The CURRENT12_CALLBACK_CURRENT callback is only triggered if the current has changed since the last triggering.

CURRENT12_CALLBACK_ANALOG_VALUE
void callback(uint16_t value, void *user_data)
Callback Parameters:
  • value – Type: uint16_t, Range: [0 to 4095]
  • user_data – Type: void *

This callback is triggered periodically with the period that is set by current12_set_analog_value_callback_period(). The parameter is the analog value of the sensor.

The CURRENT12_CALLBACK_ANALOG_VALUE callback is only triggered if the current has changed since the last triggering.

CURRENT12_CALLBACK_CURRENT_REACHED
void callback(int16_t current, void *user_data)
Callback Parameters:
  • current – Type: int16_t, Unit: 1 mA, Range: [-12500 to 12500]
  • user_data – Type: void *

This callback is triggered when the threshold as set by current12_set_current_callback_threshold() is reached. The parameter is the current of the sensor.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by current12_set_debounce_period().

CURRENT12_CALLBACK_ANALOG_VALUE_REACHED
void callback(uint16_t value, void *user_data)
Callback Parameters:
  • value – Type: uint16_t, Range: [0 to 4095]
  • user_data – Type: void *

This callback is triggered when the threshold as set by current12_set_analog_value_callback_threshold() is reached. The parameter is the analog value of the sensor.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by current12_set_debounce_period().

CURRENT12_CALLBACK_OVER_CURRENT
void callback(void *user_data)
Callback Parameters:
  • user_data – Type: void *

This callback is triggered when an over current is measured (see current12_is_over_current()).

Virtual Functions

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.

int current12_get_api_version(Current12 *current12, uint8_t ret_api_version[3])
Parameters:
  • current12 – Type: Current12 *
Output Parameters:
  • ret_api_version – Type: uint8_t[3]
    • 0: major – Type: uint8_t, Range: [0 to 255]
    • 1: minor – Type: uint8_t, Range: [0 to 255]
    • 2: revision – Type: uint8_t, Range: [0 to 255]
Returns:
  • error_code – Type: int

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.

int current12_get_response_expected(Current12 *current12, uint8_t function_id, bool *ret_response_expected)
Parameters:
  • current12 – Type: Current12 *
  • function_id – Type: uint8_t, Range: See constants
Output Parameters:
  • ret_response_expected – Type: bool
Returns:
  • error_code – Type: int

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 current12_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.

The following constants are available for this function:

For function_id:

  • CURRENT12_FUNCTION_CALIBRATE = 2
  • CURRENT12_FUNCTION_SET_CURRENT_CALLBACK_PERIOD = 5
  • CURRENT12_FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 7
  • CURRENT12_FUNCTION_SET_CURRENT_CALLBACK_THRESHOLD = 9
  • CURRENT12_FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 11
  • CURRENT12_FUNCTION_SET_DEBOUNCE_PERIOD = 13
int current12_set_response_expected(Current12 *current12, uint8_t function_id, bool response_expected)
Parameters:
  • current12 – Type: Current12 *
  • function_id – Type: uint8_t, Range: See constants
  • response_expected – Type: bool
Returns:
  • error_code – Type: int

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 constants are available for this function:

For function_id:

  • CURRENT12_FUNCTION_CALIBRATE = 2
  • CURRENT12_FUNCTION_SET_CURRENT_CALLBACK_PERIOD = 5
  • CURRENT12_FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 7
  • CURRENT12_FUNCTION_SET_CURRENT_CALLBACK_THRESHOLD = 9
  • CURRENT12_FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 11
  • CURRENT12_FUNCTION_SET_DEBOUNCE_PERIOD = 13
int current12_set_response_expected_all(Current12 *current12, bool response_expected)
Parameters:
  • current12 – Type: Current12 *
  • response_expected – Type: bool
Returns:
  • error_code – Type: int

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

Constants

CURRENT12_DEVICE_IDENTIFIER

This constant is used to identify a Current12 Bricklet.

The current12_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.

CURRENT12_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Current12 Bricklet.