C/C++ - IO-4 Bricklet

This is the description of the C/C++ API bindings for the IO-4 Bricklet. General information and technical specifications for the IO-4 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).

Output

Download (example_output.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_io4.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your IO-4 Bricklet

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

    // Create device object
    IO4 io;
    io4_create(&io, 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

    // Set pin 1 to output low
    io4_set_configuration(&io, 1 << 1, 'o', false);

    // Set pin 2 and 3 to output high
    io4_set_configuration(&io, (1 << 2) | (1 << 3), 'o', true);

    printf("Press key to exit\n");
    getchar();
    io4_destroy(&io);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Input

Download (example_input.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_io4.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your IO-4 Bricklet

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

    // Create device object
    IO4 io;
    io4_create(&io, 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 value as bitmask
    uint8_t value_mask;
    if(io4_get_value(&io, &value_mask) < 0) {
        fprintf(stderr, "Could not get value as bitmask, probably timeout\n");
        return 1;
    }

    printf("Value Mask: %u\n", value_mask);

    printf("Press key to exit\n");
    getchar();
    io4_destroy(&io);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Interrupt

Download (example_interrupt.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_io4.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your IO-4 Bricklet

// Callback function for interrupt callback
void cb_interrupt(uint8_t interrupt_mask, uint8_t value_mask, void *user_data) {
    (void)user_data; // avoid unused parameter warning

    printf("Interrupt Mask: %u\n", interrupt_mask);
    printf("Value Mask: %u\n", value_mask);
    printf("\n");
}

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

    // Create device object
    IO4 io;
    io4_create(&io, 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 interrupt callback to function cb_interrupt
    io4_register_callback(&io,
                          IO4_CALLBACK_INTERRUPT,
                          (void *)cb_interrupt,
                          NULL);

    // Enable interrupt on pin 0
    io4_set_interrupt(&io, 1 << 0);

    printf("Press key to exit\n");
    getchar();
    io4_destroy(&io);
    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
  • E_INVALID_UID = -13

as defined in ip_connection.h.

All functions listed below are thread-safe.

Basic Functions

void io4_create(IO4 *io4, const char *uid, IPConnection *ipcon)

Creates the device object io4 with the unique device ID uid and adds it to the IPConnection ipcon:

IO4 io4;
io4_create(&io4, "YOUR_DEVICE_UID", &ipcon);

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

void io4_destroy(IO4 *io4)

Removes the device object io4 from its IPConnection and destroys it. The device object cannot be used anymore afterwards.

int io4_set_value(IO4 *io4, uint8_t value_mask)

Sets the output value (high or low) with a bitmask (4bit). A 1 in the bitmask means high and a 0 in the bitmask means low.

For example: The value 3 or 0b0011 will turn the pins 0-1 high and the pins 2-3 low.

All running monoflop timers will be aborted if this function is called.

Note

This function does nothing for pins that are configured as input. Pull-up resistors can be switched on with io4_set_configuration().

int io4_get_value(IO4 *io4, uint8_t *ret_value_mask)

Returns a bitmask of the values that are currently measured. This function works if the pin is configured to input as well as if it is configured to output.

int io4_set_configuration(IO4 *io4, uint8_t selection_mask, char direction, bool value)

Configures the value and direction of the specified pins. Possible directions are 'i' and 'o' for input and output.

If the direction is configured as output, the value is either high or low (set as true or false).

If the direction is configured as input, the value is either pull-up or default (set as true or false).

For example:

  • (15, 'i', true) or (0b1111, 'i', true) will set all pins of as input pull-up.
  • (8, 'i', false) or (0b1000, 'i', false) will set pin 3 of as input default (floating if nothing is connected).
  • (3, 'o', false) or (0b0011, 'o', false) will set pins 0 and 1 as output low.
  • (4, 'o', true) or (0b0100, 'o', true) will set pin 2 of as output high.

Running monoflop timers for the specified pins will be aborted if this function is called.

The default configuration is input with pull-up.

The following defines are available for this function:

  • IO4_DIRECTION_IN = 'i'
  • IO4_DIRECTION_OUT = 'o'
int io4_get_configuration(IO4 *io4, uint8_t *ret_direction_mask, uint8_t *ret_value_mask)

Returns a value bitmask and a direction bitmask. A 1 in the direction bitmask means input and a 0 in the bitmask means output.

For example: A return value of (3, 5) or (0b0011, 0b0101) for direction and value means that:

  • pin 0 is configured as input pull-up,
  • pin 1 is configured as input default,
  • pin 2 is configured as output high and
  • pin 3 is are configured as output low.
int io4_get_edge_count(IO4 *io4, uint8_t pin, bool reset_counter, uint32_t *ret_count)

Returns the current value of the edge counter for the selected pin. You can configure the edges that are counted with io4_set_edge_count_config().

If you set the reset counter to true, the count is set back to 0 directly after it is read.

New in version 2.0.1 (Plugin).

Advanced Functions

int io4_set_monoflop(IO4 *io4, uint8_t selection_mask, uint8_t value_mask, uint32_t time)

Configures a monoflop of the pins specified by the first parameter as 4 bit long bitmask. The specified pins must be configured for output. Non-output pins will be ignored.

The second parameter is a bitmask with the desired value of the specified output pins. A 1 in the bitmask means high and a 0 in the bitmask means low.

The third parameter indicates the time (in ms) that the pins should hold the value.

If this function is called with the parameters (9, 1, 1500) or (0b1001, 0b0001, 1500): Pin 0 will get high and pin 3 will get low. In 1.5s pin 0 will get low and pin 3 will get high again.

A monoflop can be used as a fail-safe mechanism. For example: Lets assume you have a RS485 bus and an IO-4 Bricklet connected to one of the slave stacks. You can now call this function every second, with a time parameter of two seconds and pin 0 set to high. Pin 0 will be high all the time. If now the RS485 connection is lost, then pin 0 will get low in at most two seconds.

int io4_get_monoflop(IO4 *io4, uint8_t pin, uint8_t *ret_value, uint32_t *ret_time, uint32_t *ret_time_remaining)

Returns (for the given pin) the current value and the time as set by io4_set_monoflop() as well as the remaining time until the value flips.

If the timer is not running currently, the remaining time will be returned as 0.

int io4_set_selected_values(IO4 *io4, uint8_t selection_mask, uint8_t value_mask)

Sets the output value (high or low) with a bitmask, according to the selection mask. The bitmask is 4 bit long, true refers to high and false refers to low.

For example: The parameters (9, 4) or (0b0110, 0b0100) will turn pin 1 low and pin 2 high, pin 0 and 3 will remain untouched.

Running monoflop timers for the selected pins will be aborted if this function is called.

Note

This function does nothing for pins that are configured as input. Pull-up resistors can be switched on with io4_set_configuration().

int io4_set_edge_count_config(IO4 *io4, uint8_t selection_mask, uint8_t edge_type, uint8_t debounce)

Configures the edge counter for the selected pins.

The edge type parameter configures if rising edges, falling edges or both are counted if the pin is configured for input. Possible edge types are:

  • 0 = rising (default)
  • 1 = falling
  • 2 = both

The debounce time is given in ms.

Configuring an edge counter resets its value to 0.

If you don't know what any of this means, just leave it at default. The default configuration is very likely OK for you.

Default values: 0 (edge type) and 100ms (debounce time)

The following defines are available for this function:

  • IO4_EDGE_TYPE_RISING = 0
  • IO4_EDGE_TYPE_FALLING = 1
  • IO4_EDGE_TYPE_BOTH = 2

New in version 2.0.1 (Plugin).

int io4_get_edge_count_config(IO4 *io4, uint8_t pin, uint8_t *ret_edge_type, uint8_t *ret_debounce)

Returns the edge type and debounce time for the selected pin as set by io4_set_edge_count_config().

The following defines are available for this function:

  • IO4_EDGE_TYPE_RISING = 0
  • IO4_EDGE_TYPE_FALLING = 1
  • IO4_EDGE_TYPE_BOTH = 2

New in version 2.0.1 (Plugin).

int io4_get_api_version(IO4 *io4, 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 io4_get_response_expected(IO4 *io4, 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 io4_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 io4_set_response_expected() for the list of function ID defines available for this function.

int io4_set_response_expected(IO4 *io4, 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:

  • IO4_FUNCTION_SET_VALUE = 1
  • IO4_FUNCTION_SET_CONFIGURATION = 3
  • IO4_FUNCTION_SET_DEBOUNCE_PERIOD = 5
  • IO4_FUNCTION_SET_INTERRUPT = 7
  • IO4_FUNCTION_SET_MONOFLOP = 10
  • IO4_FUNCTION_SET_SELECTED_VALUES = 13
  • IO4_FUNCTION_SET_EDGE_COUNT_CONFIG = 15
int io4_set_response_expected_all(IO4 *io4, bool response_expected)

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

int io4_get_identity(IO4 *io4, 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 io4_register_callback(IO4 *io4, 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 io4_set_debounce_period(IO4 *io4, uint32_t debounce)

Sets the debounce period of the IO4_CALLBACK_INTERRUPT callback in ms.

For example: If you set this value to 100, you will get the interrupt maximal every 100ms. This is necessary if something that bounces is connected to the IO-4 Bricklet, such as a button.

The default value is 100.

int io4_get_debounce_period(IO4 *io4, uint32_t *ret_debounce)

Returns the debounce period as set by io4_set_debounce_period().

int io4_set_interrupt(IO4 *io4, uint8_t interrupt_mask)

Sets the pins on which an interrupt is activated with a bitmask. Interrupts are triggered on changes of the voltage level of the pin, i.e. changes from high to low and low to high.

For example: An interrupt bitmask of 10 or 0b1010 will enable the interrupt for pins 1 and 3.

The interrupt is delivered with the IO4_CALLBACK_INTERRUPT callback.

int io4_get_interrupt(IO4 *io4, uint8_t *ret_interrupt_mask)

Returns the interrupt bitmask as set by io4_set_interrupt().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the io4_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);
}

io4_register_callback(&io4, IO4_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.

IO4_CALLBACK_INTERRUPT
void callback(uint8_t interrupt_mask, uint8_t value_mask, void *user_data)

This callback is triggered whenever a change of the voltage level is detected on pins where the interrupt was activated with io4_set_interrupt().

The values are a bitmask that specifies which interrupts occurred and the current value bitmask.

For example:

  • (1, 1) or (0b0001, 0b0001) means that an interrupt on pin 0 occurred and currently pin 0 is high and pins 1-3 are low.
  • (9, 14) or (0b1001, 0b1110) means that interrupts on pins 0 and 3 occurred and currently pin 0 is low and pins 1-3 are high.
IO4_CALLBACK_MONOFLOP_DONE
void callback(uint8_t selection_mask, uint8_t value_mask, void *user_data)

This callback is triggered whenever a monoflop timer reaches 0. The parameters contain the involved pins and the current value of the pins (the value after the monoflop).

Constants

IO4_DEVICE_IDENTIFIER

This constant is used to identify a IO-4 Bricklet.

The io4_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.

IO4_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a IO-4 Bricklet.