This is the description of the C/C++ API bindings for the Stepper Brick. General information and technical specifications for the Stepper Brick 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).
Download (example_configuration.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 "brick_stepper.h"
#define HOST "localhost"
#define PORT 4223
#define UID "a4LCLTYxDK9" // Change to your UID
int main() {
// Create IP connection
IPConnection ipcon;
ipcon_create(&ipcon);
// Create device object
Stepper stepper;
stepper_create(&stepper, 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
stepper_set_motor_current(&stepper, 800); // 800mA
stepper_set_step_mode(&stepper, 8); // 1/8 step mode
stepper_set_max_velocity(&stepper, 2000); // Velocity 2000 steps/s
// Slow acceleration (500 steps/s^2),
// Fast deacceleration (5000 steps/s^2)
stepper_set_speed_ramping(&stepper, 500, 5000);
stepper_enable(&stepper);
stepper_set_steps(&stepper, 60000); // Drive 60000 steps forward
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 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 | #include <stdio.h>
#include <stdlib.h>
#include "ip_connection.h"
#include "brick_stepper.h"
#define HOST "localhost"
#define PORT 4223
#define UID "a4LCLTYxDK9" // Change to your UID
// Use position reached callback to program random movement
void cb_reached(int32_t position, void *user_data) {
Stepper *stepper = (Stepper *)user_data;
int32_t steps;
(void)position;
if(rand() % 2) {
steps = (rand() % 4000) + 1000; // steps (forward)
printf("Driving forward: %d steps\n", steps);
} else {
steps = -((rand() % 4000) + 1000); // steps (backward)
printf("Driving backward: %d steps\n", steps);
}
int16_t vel = (rand() % 1800) + 200; // steps/s
uint16_t acc = (rand() % 900) + 100; // steps/s^2
uint16_t dec = (rand() % 900) + 100; // steps/s^2
printf("Configuration (vel, acc, dec): %d, %d %d\n", vel, acc, dec);
stepper_set_speed_ramping(stepper, acc, dec);
stepper_set_max_velocity(stepper, vel);
stepper_set_steps(stepper, steps);
}
int main() {
// Create IP connection
IPConnection ipcon;
ipcon_create(&ipcon);
// Create device object
Stepper stepper;
stepper_create(&stepper, 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
// Register "position reached callback" to cb_reached
// cb_reached will be called every time a position set with
// set_steps or set_target_position is reached
stepper_register_callback(&stepper,
STEPPER_CALLBACK_POSITION_REACHED,
(void *)cb_reached,
&stepper);
stepper_enable(&stepper);
// Drive one step forward to get things going
stepper_set_steps(&stepper, 1);
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 stepper with the unique device ID uid and adds it to the IPConnection ipcon:
Stepper stepper;
stepper_create(&stepper, "YOUR_DEVICE_UID", &ipcon);
This device object can be used after the IP connection has been connected (see examples above).
Removes the device object stepper from its IPConnection and destroys it. The device object cannot be used anymore afterwards.
Sets the maximum velocity of the stepper motor in steps per second. This function does not start the motor, it merely sets the maximum velocity the stepper motor is accelerated to. To get the motor running use either stepper_set_target_position(), stepper_set_steps(), stepper_drive_forward() or stepper_drive_backward().
Returns the velocity as set by stepper_set_max_velocity().
Returns the current velocity of the stepper motor in steps per second.
Sets the acceleration and deacceleration of the stepper motor. The values are given in steps/s². An acceleration of 1000 means, that every second the velocity is increased by 1000 steps/s.
For example: If the current velocity is 0 and you want to accelerate to a velocity of 8000 steps/s in 10 seconds, you should set an acceleration of 800 steps/s².
An acceleration/deacceleration of 0 means instantaneous acceleration/deacceleration (not recommended)
The default value is 1000 for both
Returns the acceleration and deacceleration as set by stepper_set_speed_ramping().
Executes an active full brake.
Warning
This function is for emergency purposes, where an immediate brake is necessary. Depending on the current velocity and the strength of the motor, a full brake can be quite violent.
Call stepper_stop() if you just want to stop the motor.
Sets the number of steps the stepper motor should run. Positive values will drive the motor forward and negative values backward. The velocity, acceleration and deacceleration as set by stepper_set_max_velocity() and stepper_set_speed_ramping() will be used.
Returns the last steps as set by stepper_set_steps().
Returns the remaining steps of the last call of stepper_set_steps(). For example, if stepper_set_steps() is called with 2000 and stepper_get_remaining_steps() is called after the motor has run for 500 steps, it will return 1500.
Drives the stepper motor forward until stepper_drive_backward() or stepper_stop() is called. The velocity, acceleration and deacceleration as set by stepper_set_max_velocity() and stepper_set_speed_ramping() will be used.
Drives the stepper motor backward until stepper_drive_forward() or stepper_stop() is triggered. The velocity, acceleration and deacceleration as set by stepper_set_max_velocity() and stepper_set_speed_ramping() will be used.
Stops the stepper motor with the deacceleration as set by stepper_set_speed_ramping().
Sets the current in mA with which the motor will be driven. The minimum value is 100mA, the maximum value 2291mA and the default value is 800mA.
Warning
Do not set this value above the specifications of your stepper motor. Otherwise it may damage your motor.
Returns the current as set by stepper_set_motor_current().
Enables the driver chip. The driver parameters can be configured (maximum velocity, acceleration, etc) before it is enabled.
Disables the driver chip. The configurations are kept (maximum velocity, acceleration, etc) but the motor is not driven until it is enabled again.
Returns true if the driver chip is enabled, false otherwise.
Sets the current steps of the internal step counter. This can be used to set the current position to 0 when some kind of starting position is reached (e.g. when a CNC machine reaches a corner).
Returns the current position of the stepper motor in steps. On startup the position is 0. The steps are counted with all possible driving functions (stepper_set_target_position(), stepper_set_steps(), stepper_drive_forward() or stepper_drive_backward()). It also is possible to reset the steps to 0 or set them to any other desired value with stepper_set_current_position().
Sets the target position of the stepper motor in steps. For example, if the current position of the motor is 500 and stepper_set_target_position() is called with 1000, the stepper motor will drive 500 steps forward. It will use the velocity, acceleration and deacceleration as set by stepper_set_max_velocity() and stepper_set_speed_ramping().
A call of stepper_set_target_position() with the parameter x is equivalent to a call of stepper_set_steps() with the parameter (x - stepper_get_current_position()).
Returns the last target position as set by stepper_set_target_position().
Sets the step mode of the stepper motor. Possible values are:
A higher value will increase the resolution and decrease the torque of the stepper motor.
The default value is 8 (Eighth Step).
The following defines are available for this function:
Returns the step mode as set by stepper_set_step_mode().
The following defines are available for this function:
Returns the stack input voltage in mV. The stack input voltage is the voltage that is supplied via the stack, i.e. it is given by a Step-Down or Step-Up Power Supply.
Returns the external input voltage in mV. The external input voltage is given via the black power input connector on the Stepper Brick.
If there is an external input voltage and a stack input voltage, the motor will be driven by the external input voltage. If there is only a stack voltage present, the motor will be driven by this voltage.
Warning
This means, if you have a high stack voltage and a low external voltage, the motor will be driven with the low external voltage. If you then remove the external connection, it will immediately be driven by the high stack voltage
Returns the current consumption of the motor in mA.
Sets the decay mode of the stepper motor. The possible value range is between 0 and 65535. A value of 0 sets the fast decay mode, a value of 65535 sets the slow decay mode and a value in between sets the mixed decay mode.
Changing the decay mode is only possible if synchronous rectification is enabled (see stepper_set_sync_rect()).
For a good explanation of the different decay modes see this blog post by Avayan.
A good decay mode is unfortunately different for every motor. The best way to work out a good decay mode for your stepper motor, if you can't measure the current with an oscilloscope, is to listen to the sound of the motor. If the value is too low, you often hear a high pitched sound and if it is too high you can often hear a humming sound.
Generally, fast decay mode (small value) will be noisier but also allow higher motor speeds.
The default value is 10000.
Note
There is unfortunately no formula to calculate a perfect decay mode for a given stepper motor. If you have problems with loud noises or the maximum motor speed is too slow, you should try to tinker with the decay value
Returns the decay mode as set by stepper_set_decay().
Turns synchronous rectification on or off (true or false).
With synchronous rectification on, the decay can be changed (see stepper_set_decay()). Without synchronous rectification fast decay is used.
For an explanation of synchronous rectification see here.
Warning
If you want to use high speeds (> 10000 steps/s) for a large stepper motor with a large inductivity we strongly suggest that you disable synchronous rectification. Otherwise the Brick may not be able to cope with the load and overheat.
The default value is false.
Returns true if synchronous rectification is enabled, false otherwise.
Sets the time base of the velocity and the acceleration of the stepper brick (in seconds).
For example, if you want to make one step every 1.5 seconds, you can set the time base to 15 and the velocity to 10. Now the velocity is 10steps/15s = 1steps/1.5s.
The default value is 1.
Returns the time base as set by stepper_set_time_base().
Returns the following parameters: The current velocity, the current position, the remaining steps, the stack voltage, the external voltage and the current consumption of the stepper motor.
There is also a callback for this function, see STEPPER_CALLBACK_ALL_DATA.
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 stepper_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 stepper_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.
Enables the status LED.
The status LED is the blue LED next to the USB connector. If enabled is is on and it flickers if data is transfered. If disabled it is always off.
The default state is enabled.
New in version 2.3.1 (Firmware).
Disables the status LED.
The status LED is the blue LED next to the USB connector. If enabled is is on and it flickers if data is transfered. If disabled it is always off.
The default state is enabled.
New in version 2.3.1 (Firmware).
Returns true if the status LED is enabled, false otherwise.
New in version 2.3.1 (Firmware).
Returns the firmware and protocol version and the name of the Bricklet for a given port.
This functions sole purpose is to allow automatic flashing of v1.x.y Bricklet plugins.
Returns the temperature in °C/10 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 an accuracy of +-15%. Practically it is only useful as an indicator for temperature changes.
Calling this function will reset the Brick. Calling this function on a Brick inside of a stack will reset the whole stack.
After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!
Returns the UID, the UID where the Brick is connected to, the position, the hardware and firmware version as well as the device identifier.
The position can be '0'-'8' (stack position).
The device identifier numbers can be found here. There is also a constant for the device identifier of this Brick.
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 minimum voltage in mV, below which the STEPPER_CALLBACK_UNDER_VOLTAGE callback is triggered. The minimum possible value that works with the Stepper Brick is 8V. You can use this function to detect the discharge of a battery that is used to drive the stepper motor. If you have a fixed power supply, you likely do not need this functionality.
The default value is 8V.
Returns the minimum voltage as set by stepper_set_minimum_voltage().
Sets the period in ms with which the STEPPER_CALLBACK_ALL_DATA callback is triggered periodically. A value of 0 turns the callback off.
Returns the period as set by stepper_set_all_data_period().
Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the stepper_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); } stepper_register_callback(&stepper, STEPPER_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(uint16_t voltage, void *user_data)
This callback is triggered when the input voltage drops below the value set by stepper_set_minimum_voltage(). The parameter is the current voltage given in mV.
void callback(int32_t position, void *user_data)
This callback is triggered when a position set by stepper_set_steps() or stepper_set_target_position() is reached.
Note
Since we can't get any feedback from the stepper motor, this only works if the acceleration (see stepper_set_speed_ramping()) is set smaller or equal to the maximum acceleration of the motor. Otherwise the motor will lag behind the control value and the callback will be triggered too early.
void callback(uint16_t current_velocity, int32_t current_position, int32_t remaining_steps, uint16_t stack_voltage, uint16_t external_voltage, uint16_t current_consumption, void *user_data)
This callback is triggered periodically with the period that is set by stepper_set_all_data_period(). The parameters are: the current velocity, the current position, the remaining steps, the stack voltage, the external voltage and the current consumption of the stepper motor.
void callback(uint8_t state_new, uint8_t state_previous, void *user_data)
This callback is triggered whenever the Stepper Brick enters a new state. It returns the new state as well as the previous state.
Possible states are:
The following defines are available for this function:
This constant is used to identify a Stepper Brick.
The stepper_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.