Shell - Stepper Brick

This is the description of the Shell 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 Shell API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Configuration

Download (example-configuration.sh)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
#!/bin/sh
# Connects to localhost:4223 by default, use --host and --port to change this

uid=XXYYZZ # Change XXYYZZ to the UID of your Stepper Brick

tinkerforge call stepper-brick $uid set-motor-current 800 # 800mA
tinkerforge call stepper-brick $uid set-step-mode step-mode-eighth-step # 1/8 step mode
tinkerforge call stepper-brick $uid set-max-velocity 2000 # Velocity 2000 steps/s

# Slow acceleration (500 steps/s^2),
# Fast deacceleration (5000 steps/s^2)
tinkerforge call stepper-brick $uid set-speed-ramping 500 5000

tinkerforge call stepper-brick $uid enable # Enable motor power
tinkerforge call stepper-brick $uid set-steps 60000 # Drive 60000 steps forward

echo "Press key to exit"; read dummy

tinkerforge call stepper-brick $uid disable

Callback

Download (example-callback.sh)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
#!/bin/sh
# Connects to localhost:4223 by default, use --host and --port to change this

uid=XXYYZZ # Change XXYYZZ to the UID of your Stepper Brick

# Use position reached callback to program random movement
tinkerforge dispatch stepper-brick $uid position-reached\
 --execute "echo Changing configuration;
            tinkerforge call stepper-brick $uid set-max-velocity $(((RANDOM%1800)+1200));
            tinkerforge call stepper-brick $uid set-speed-ramping $(((RANDOM%900)+100)) $(((RANDOM%900)+100));
            if [ $((RANDOM % 2)) -eq 1 ];
            then tinkerforge call stepper-brick $uid set-steps $(((RANDOM%4000)+1000));
            else tinkerforge call stepper-brick $uid set-steps $(((RANDOM%4000)-5000));
            fi" &

tinkerforge call stepper-brick $uid enable # Enable motor power
tinkerforge call stepper-brick $uid set-steps 1 # Drive one step forward to get things going

echo "Press key to exit"; read dummy

tinkerforge call stepper-brick $uid disable

kill -- -$$ # Stop callback dispatch in background

API

Possible exit codes for all tinkerforge commands are:

  • 1: interrupted (ctrl+c)
  • 2: syntax error
  • 21: Python 2.5 or newer is required
  • 22: Python argparse module is missing
  • 23: socket error
  • 24: other exception
  • 25: invalid placeholder in format string
  • 26: authentication error
  • 201: timeout occurred
  • 209: invalid argument value
  • 210: function is not supported
  • 211: unknown error

Command Structure

The common options of the call and dispatch commands are documented here. The specific command structure is shown below.

tinkerforge call stepper-brick [<option>..] <uid> <function> [<argument>..]
Parameters:
  • <uid> -- string
  • <function> -- string

The call command is used to call a function of the Stepper Brick. It can take several options:

  • --help shows help for the specific call command and exits
  • --list-functions shows a list of known functions of the Stepper Brick and exits
tinkerforge dispatch stepper-brick [<option>..] <uid> <callback>
Parameters:
  • <uid> -- string
  • <callback> -- string

The dispatch command is used to dispatch a callback of the Stepper Brick. It can take several options:

  • --help shows help for the specific dispatch command and exits
  • --list-callbacks shows a list of known callbacks of the Stepper Brick and exits
tinkerforge call stepper-brick <uid> <function> [<option>..] [<argument>..]
Parameters:
  • <uid> -- string
  • <function> -- string

The <function> to be called can take different options depending of its kind. All functions can take the following options:

  • --help shows help for the specific function and exits

Getter functions can take the following options:

  • --execute <command> shell command line to execute for each incoming response (see section about output formatting for details)

Setter functions can take the following options:

  • --expect-response requests response and waits for it

The --expect-response option for setter functions allows to detect timeouts and other error conditions calls of setters as well. The device will then send a response for this purpose. If this option is not given for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

tinkerforge dispatch stepper-brick <uid> <callback> [<option>..]
Parameters:
  • <uid> -- string
  • <callback> -- string

The <callback> to be dispatched can take several options:

  • --help shows help for the specific callback and exits
  • --execute <command> shell command line to execute for each incoming response (see section about output formatting for details)

Basic Functions

tinkerforge call stepper-brick <uid> set-max-velocity <velocity>
Parameters:
  • <velocity> -- int
Output:

no output

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 set-target-position, set-steps, drive-forward or drive-backward.

tinkerforge call stepper-brick <uid> get-max-velocity
Output:
  • velocity -- int

Returns the velocity as set by set-max-velocity.

tinkerforge call stepper-brick <uid> get-current-velocity
Output:
  • velocity -- int

Returns the current velocity of the stepper motor in steps per second.

tinkerforge call stepper-brick <uid> set-speed-ramping <acceleration> <deacceleration>
Parameters:
  • <acceleration> -- int
  • <deacceleration> -- int
Output:

no output

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

tinkerforge call stepper-brick <uid> get-speed-ramping
Output:
  • acceleration -- int
  • deacceleration -- int

Returns the acceleration and deacceleration as set by set-speed-ramping.

tinkerforge call stepper-brick <uid> full-brake
Output:no output

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 stop if you just want to stop the motor.

tinkerforge call stepper-brick <uid> set-steps <steps>
Parameters:
  • <steps> -- int
Output:

no output

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 set-max-velocity and set-speed-ramping will be used.

tinkerforge call stepper-brick <uid> get-steps
Output:
  • steps -- int

Returns the last steps as set by set-steps.

tinkerforge call stepper-brick <uid> get-remaining-steps
Output:
  • steps -- int

Returns the remaining steps of the last call of set-steps. For example, if set-steps is called with 2000 and get-remaining-steps is called after the motor has run for 500 steps, it will return 1500.

tinkerforge call stepper-brick <uid> drive-forward
Output:no output

Drives the stepper motor forward until drive-backward or stop is called. The velocity, acceleration and deacceleration as set by set-max-velocity and set-speed-ramping will be used.

tinkerforge call stepper-brick <uid> drive-backward
Output:no output

Drives the stepper motor backward until drive-forward or stop is triggered. The velocity, acceleration and deacceleration as set by set-max-velocity and set-speed-ramping will be used.

tinkerforge call stepper-brick <uid> stop
Output:no output

Stops the stepper motor with the deacceleration as set by set-speed-ramping.

tinkerforge call stepper-brick <uid> set-motor-current <current>
Parameters:
  • <current> -- int
Output:

no output

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.

tinkerforge call stepper-brick <uid> get-motor-current
Output:
  • current -- int

Returns the current as set by set-motor-current.

tinkerforge call stepper-brick <uid> enable
Output:no output

Enables the driver chip. The driver parameters can be configured (maximum velocity, acceleration, etc) before it is enabled.

tinkerforge call stepper-brick <uid> disable
Output:no output

Disables the driver chip. The configurations are kept (maximum velocity, acceleration, etc) but the motor is not driven until it is enabled again.

tinkerforge call stepper-brick <uid> is-enabled
Output:
  • enabled -- bool

Returns true if the driver chip is enabled, false otherwise.

Advanced Functions

tinkerforge call stepper-brick <uid> set-current-position <position>
Parameters:
  • <position> -- int
Output:

no output

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).

tinkerforge call stepper-brick <uid> get-current-position
Output:
  • position -- int

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 (set-target-position, set-steps, drive-forward or drive-backward). It also is possible to reset the steps to 0 or set them to any other desired value with set-current-position.

tinkerforge call stepper-brick <uid> set-target-position <position>
Parameters:
  • <position> -- int
Output:

no output

Sets the target position of the stepper motor in steps. For example, if the current position of the motor is 500 and 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 set-max-velocity and set-speed-ramping.

A call of set-target-position with the parameter x is equivalent to a call of set-steps with the parameter (x - get-current-position).

tinkerforge call stepper-brick <uid> get-target-position
Output:
  • position -- int

Returns the last target position as set by set-target-position.

tinkerforge call stepper-brick <uid> set-step-mode <mode>
Parameters:
  • <mode> -- int (has symbols)
Output:

no output

Sets the step mode of the stepper motor. Possible values are:

  • Full Step = 1
  • Half Step = 2
  • Quarter Step = 4
  • Eighth Step = 8

A higher value will increase the resolution and decrease the torque of the stepper motor.

The default value is 8 (Eighth Step).

The following symbols are available for this function:

  • step-mode-full-step = 1, for <mode>
  • step-mode-half-step = 2, for <mode>
  • step-mode-quarter-step = 4, for <mode>
  • step-mode-eighth-step = 8, for <mode>
tinkerforge call stepper-brick <uid> get-step-mode
Output:
  • mode -- int (has symbols)

Returns the step mode as set by set-step-mode.

The following symbols are available for this function:

  • step-mode-full-step = 1, for mode
  • step-mode-half-step = 2, for mode
  • step-mode-quarter-step = 4, for mode
  • step-mode-eighth-step = 8, for mode
tinkerforge call stepper-brick <uid> get-stack-input-voltage
Output:
  • voltage -- int

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.

tinkerforge call stepper-brick <uid> get-external-input-voltage
Output:
  • voltage -- int

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

tinkerforge call stepper-brick <uid> get-current-consumption
Output:
  • current -- int

Returns the current consumption of the motor in mA.

tinkerforge call stepper-brick <uid> set-decay <decay>
Parameters:
  • <decay> -- int
Output:

no output

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 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

tinkerforge call stepper-brick <uid> get-decay
Output:
  • decay -- int

Returns the decay mode as set by set-decay.

tinkerforge call stepper-brick <uid> set-sync-rect <sync-rect>
Parameters:
  • <sync-rect> -- bool
Output:

no output

Turns synchronous rectification on or off (true or false).

With synchronous rectification on, the decay can be changed (see 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.

tinkerforge call stepper-brick <uid> is-sync-rect
Output:
  • sync-rect -- bool

Returns true if synchronous rectification is enabled, false otherwise.

tinkerforge call stepper-brick <uid> set-time-base <time-base>
Parameters:
  • <time-base> -- int
Output:

no output

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.

tinkerforge call stepper-brick <uid> get-time-base
Output:
  • time-base -- int

Returns the time base as set by set-time-base.

tinkerforge call stepper-brick <uid> get-all-data
Output:
  • current-velocity -- int
  • current-position -- int
  • remaining-steps -- int
  • stack-voltage -- int
  • external-voltage -- int
  • current-consumption -- int

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 all-data callback.

tinkerforge call stepper-brick <uid> set-spitfp-baudrate-config <enable-dynamic-baudrate> <minimum-dynamic-baudrate>
Parameters:
  • <enable-dynamic-baudrate> -- bool
  • <minimum-dynamic-baudrate> -- int
Output:

no output

The SPITF protocol can be used with a dynamic baudrate. If the dynamic baudrate is enabled, the Brick will try to adapt the baudrate for the communication between Bricks and Bricklets according to the amount of data that is transferred.

The baudrate will be increased exponentially if lots of data is send/received and decreased linearly if little data is send/received.

This lowers the baudrate in applications where little data is transferred (e.g. a weather station) and increases the robustness. If there is lots of data to transfer (e.g. Thermal Imaging Bricklet) it automatically increases the baudrate as needed.

In cases where some data has to transferred as fast as possible every few seconds (e.g. RS485 Bricklet with a high baudrate but small payload) you may want to turn the dynamic baudrate off to get the highest possible performance.

The maximum value of the baudrate can be set per port with the function set-spitfp-baudrate. If the dynamic baudrate is disabled, the baudrate as set by set-spitfp-baudrate will be used statically.

The minimum dynamic baudrate has a value range of 400000 to 2000000 baud.

By default dynamic baudrate is enabled and the minimum dynamic baudrate is 400000.

New in version 2.3.6 (Firmware).

tinkerforge call stepper-brick <uid> get-spitfp-baudrate-config
Output:
  • enable-dynamic-baudrate -- bool
  • minimum-dynamic-baudrate -- int

Returns the baudrate config, see set-spitfp-baudrate-config.

New in version 2.3.6 (Firmware).

tinkerforge call stepper-brick <uid> get-send-timeout-count <communication-method>
Parameters:
  • <communication-method> -- int (has symbols)
Output:
  • timeout-count -- int

Returns the timeout count for the different communication methods.

The methods 0-2 are available for all Bricks, 3-7 only for Master Bricks.

This function is mostly used for debugging during development, in normal operation the counters should nearly always stay at 0.

The following symbols are available for this function:

  • communication-method-none = 0, for <communication-method>
  • communication-method-usb = 1, for <communication-method>
  • communication-method-spi-stack = 2, for <communication-method>
  • communication-method-chibi = 3, for <communication-method>
  • communication-method-rs485 = 4, for <communication-method>
  • communication-method-wifi = 5, for <communication-method>
  • communication-method-ethernet = 6, for <communication-method>
  • communication-method-wifi-v2 = 7, for <communication-method>

New in version 2.3.4 (Firmware).

tinkerforge call stepper-brick <uid> set-spitfp-baudrate <bricklet-port> <baudrate>
Parameters:
  • <bricklet-port> -- char
  • <baudrate> -- int
Output:

no output

Sets the baudrate for a specific Bricklet port ('a' - 'd'). The baudrate can be in the range 400000 to 2000000.

If you want to increase the throughput of Bricklets you can increase the baudrate. If you get a high error count because of high interference (see get-spitfp-error-count) you can decrease the baudrate.

If the dynamic baudrate feature is enabled, the baudrate set by this function corresponds to the maximum baudrate (see set-spitfp-baudrate-config).

Regulatory testing is done with the default baudrate. If CE compatibility or similar is necessary in you applications we recommend to not change the baudrate.

The default baudrate for all ports is 1400000.

New in version 2.3.3 (Firmware).

tinkerforge call stepper-brick <uid> get-spitfp-baudrate <bricklet-port>
Parameters:
  • <bricklet-port> -- char
Output:
  • baudrate -- int

Returns the baudrate for a given Bricklet port, see set-spitfp-baudrate.

New in version 2.3.3 (Firmware).

tinkerforge call stepper-brick <uid> get-spitfp-error-count <bricklet-port>
Parameters:
  • <bricklet-port> -- char
Output:
  • error-count-ack-checksum -- int
  • error-count-message-checksum -- int
  • error-count-frame -- int
  • error-count-overflow -- int

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Brick side. All Bricklets have a similar function that returns the errors on the Bricklet side.

New in version 2.3.3 (Firmware).

tinkerforge call stepper-brick <uid> enable-status-led
Output:no output

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).

tinkerforge call stepper-brick <uid> disable-status-led
Output:no output

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).

tinkerforge call stepper-brick <uid> is-status-led-enabled
Output:
  • enabled -- bool

Returns true if the status LED is enabled, false otherwise.

New in version 2.3.1 (Firmware).

tinkerforge call stepper-brick <uid> get-protocol1-bricklet-name <port>
Parameters:
  • <port> -- char
Output:
  • protocol-version -- int
  • firmware-version -- int,int,int
  • name -- string

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.

tinkerforge call stepper-brick <uid> get-chip-temperature
Output:
  • temperature -- int

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.

tinkerforge call stepper-brick <uid> reset
Output:no output

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!

tinkerforge call stepper-brick <uid> get-identity
Output:
  • uid -- string
  • connected-uid -- string
  • position -- char
  • hardware-version -- int,int,int
  • firmware-version -- int,int,int
  • device-identifier -- int (has symbols)

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

Callback Configuration Functions

tinkerforge call stepper-brick <uid> set-minimum-voltage <voltage>
Parameters:
  • <voltage> -- int
Output:

no output

Sets the minimum voltage in mV, below which the 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.

tinkerforge call stepper-brick <uid> get-minimum-voltage
Output:
  • voltage -- int

Returns the minimum voltage as set by set-minimum-voltage.

tinkerforge call stepper-brick <uid> set-all-data-period <period>
Parameters:
  • <period> -- int
Output:

no output

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

tinkerforge call stepper-brick <uid> get-all-data-period
Output:
  • period -- int

Returns the period as set by set-all-data-period.

Callbacks

Callbacks can be used to receive time critical or recurring data from the device:

tinkerforge dispatch stepper-brick <uid> example

The available callbacks 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.

tinkerforge dispatch stepper-brick <uid> under-voltage
Output:
  • voltage -- int

This callback is triggered when the input voltage drops below the value set by set-minimum-voltage. The parameter is the current voltage given in mV.

tinkerforge dispatch stepper-brick <uid> position-reached
Output:
  • position -- int

This callback is triggered when a position set by set-steps or set-target-position is reached.

Note

Since we can't get any feedback from the stepper motor, this only works if the acceleration (see 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.

tinkerforge dispatch stepper-brick <uid> all-data
Output:
  • current-velocity -- int
  • current-position -- int
  • remaining-steps -- int
  • stack-voltage -- int
  • external-voltage -- int
  • current-consumption -- int

This callback is triggered periodically with the period that is set by 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.

tinkerforge dispatch stepper-brick <uid> new-state
Output:
  • state-new -- int (has symbols)
  • state-previous -- int (has symbols)

This callback is triggered whenever the Stepper Brick enters a new state. It returns the new state as well as the previous state.

The following symbols are available for this function:

  • state-stop = 1, for state-new and state-previous
  • state-acceleration = 2, for state-new and state-previous
  • state-run = 3, for state-new and state-previous
  • state-deacceleration = 4, for state-new and state-previous
  • state-direction-change-to-forward = 5, for state-new and state-previous
  • state-direction-change-to-backward = 6, for state-new and state-previous