docs: Add Firmware_Commands.md with information on common firmware commands
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
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Kevin O'Connor
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This document provides high-level information on common firmware
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commands. It is not an authoritative reference for these commands, nor
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is it an exclusive list of all available firmware commands.
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This document may be useful for users needing to configure a set of
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hardware actions that their printer may require at startup (via the
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"custom" field in the printer config file), and it may be useful for
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developers wishing to obtain a high-level feel for available firmware
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commands.
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See the [protocol](Protocol.md) document for more information on the
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format of commands and their low-level transmission. The commands here
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are described using their "printf" style syntax - for those unfamiliar
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with that format, just note that where a '%...' sequence is seen it
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should be replaced with an actual integer.
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Startup Commands
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================
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It may be necessary to take certain one-time actions to configure the
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micro-controller and its peripherals. This section lists common
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commands available for that purpose. Unlike other firmware commands,
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these commands run as soon as they are received by the firmware and
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they do not require any particular setup.
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These commands are most useful in the "custom" block of the "mcu"
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section of the printer configuration file. This feature is typically
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used to configure the initial settings of LEDs, to configure
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micro-stepping pins, to configure a digipot, etc.
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Several of these commands will take a "pin=%u" parameter. The
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low-level firmware uses integer encodings of the hardware pin numbers,
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but to make things more readable the host will translate human
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readable pin names (eg, "PA3") to their equivalent integer
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encodings. By convention, any parameter named "pin" or that has a
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"_pin" suffix will use pin name translation by the host.
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Common startup commands:
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* set_digital_out pin=%u value=%c : This command immediately
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configures the given pin as a digital out GPIO and it sets it to
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either a low level (value=0) or a high level (value=1). This command
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may be useful for configuring the initial value of LEDs and for
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configuring the initial value of stepper driver micro-stepping pins.
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* set_pwm_out pin=%u cycle_ticks=%u value=%c : This command will
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immediately configure the given pin to use hardware based
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pulse-width-modulation (PWM) with the given number of
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cycle_ticks. The "cycle_ticks" is the amount of time (in MCU clock
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ticks) in a complete power on and power off cycle. A cycle_ticks
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value of 1 can be used to request the fastest possible cycle
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time. The specified "value" is between 0 and 255 with 0 indicating a
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full off state and 255 indicating a full on state. This command may
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be useful for enabling CPU and nozzle cooling fans.
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* send_spi_message pin=%u msg=%*s : This command can be used to
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transmit messages to a serial-peripheral-interface (SPI) component
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connected to the micro-controller. It has been used to configure the
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startup settings of AD5206 digipots. The 'pin' parameter specifies
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the chip select line to use during the transmission. The 'msg'
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indicates the binary message to transmit to the given chip.
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Firmware configuration
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======================
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Most commands in the firmware require an initial setup before they can
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be successfully invoked. This section provides a high-level overview
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of the micro-controller configuration process. This section and the
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following sections are likely only of interest to developers
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interested in the internal details of Klipper.
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When the host first connects to the firmware it always starts by
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obtaining the firmware's data dictionary (see [protocol](Protocol.md)
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for more information). After the data dictionary is obtained the host
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will check if the firmware is in a "configured" state and configure it
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if not. Configuration involves the following phases:
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* get_config : The host starts by checking if the firmware is already
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configured. The firmware responds to this command with a "config"
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response message. At micro-controller power-on the firmware always
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starts in an unconfigured state. It remains in this state until the
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host completes the configuration processes (by issuing a
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finalize_config command). If the firmware is already configured (and
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is configured with the desired settings) from a previous
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host/firmware session then no further action is needed by the host
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and the configuration process ends successfully.
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* allocate_oids count=%c : This command is issued to inform the
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firmware the maximum number of object-ids (oid) that the host
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requires. It is only valid to issue this command once. An oid is an
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integer identifier allocated to each stepper, each endstop, and each
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schedulable gpio pin. The host determines in advance the number of
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oids it will require to operate the hardware and passes this to the
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firmware so that the firmware may allocate sufficient memory to
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store a mapping from oid to internal firmware object.
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* config_XXX oid=%c ... : By convention any command starting with the
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"config_" prefix creates a new firmware object and assigns the given
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oid to it. For example, the config_digital_out command will
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configure the specified pin as a digital output GPIO and create an
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internal object that the host can use to schedule changes to the
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given GPIO. The oid parameter passed into the config command is
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selected by the host and must be between zero and the maximum count
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supplied in the allocate_oids command. The config commands may only
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be run when the firmware is not in a configured state (ie, prior to
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the host sending finalize_config) and after the allocate_oids
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command has been sent.
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* finalize_config crc=%u : The finalize_config command transitions the
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firmware from an unconfigured state to a configured state. The crc
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parameter passed to the firmware is stored in the firmware and
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provided back to the host in "config" response messages. By
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convention, the host takes a 32bit CRC of the firmware configuration
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it will request and at the start of subsequent host/firmware
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communication sessions it checks that the CRC stored in the firmware
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exactly matches its desired CRC. If the CRC does not match then the
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host knows the firmware has not been configured in the state desired
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by the host.
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Common firmware objects
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-----------------------
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This section lists some commonly used config commands.
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* config_digital_out oid=%c pin=%u default_value=%c max_duration=%u :
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This command creates an internal firmware object for the given GPIO
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'pin'. The pin will be configured in digital output mode and set to
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an initial value as specified by 'default_value' (0 for low, 1 for
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high). Creating a digital_out object allows the host to schedule
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GPIO updates for the given pin at specified times (see the
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schedule_digital_out command described below). Should the firmware
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go into shutdown mode then all configured digital_out objects will
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be set back to their default values. The 'max_duration' parameter is
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used to implement a safety check - if it is non-zero then it is the
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maximum number of clock ticks that the host may set the given GPIO
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to a non-default value without further updates. For example, if the
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default_value is zero and the max_duration is 16000 then if the host
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sets the gpio to a value of one then it must schedule another update
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to the gpio pin (to either zero or one) within 16000 clock
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ticks. This safety feature can be used with heater pins to ensure
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the host does not set the heater to a value of one and then go
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off-line.
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* config_pwm_out oid=%c pin=%u cycle_ticks=%u default_value=%c
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max_duration=%u : This command creates an internal object for
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hardware based PWM pins that the host may schedule updates for. Its
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usage is analogous to config_digital_out - see the description of
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the 'set_pwm_out' and 'config_digital_out' commands for parameter
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description.
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* config_soft_pwm_out oid=%c pin=%u cycle_ticks=%u default_value=%c
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max_duration=%u : This command creates an internal firmware object
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for software implemented PWM. Unlike hardware pwm pins, a software
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pwm object does not require any special hardware support (other than
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the ability to configure the pin as a digital output GPIO). Because
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the output switching is implemented in the software of the firmware,
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it is recommended that the cycle_ticks parameter correspond to a
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time of 10ms or greater. See the description of the 'set_pwm_out'
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and 'config_digital_out' commands for parameter description.
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* config_analog_in oid=%c pin=%u : This command is used to configure a
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pin in analog input sampling mode. Once configured, the pin can be
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sampled at regular interval using the query_analog_in command (see
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below).
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* config_stepper oid=%c step_pin=%c dir_pin=%c min_stop_interval=%u
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invert_step=%c : This command creates an internal stepper
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object. The 'step_pin' and 'dir_pin' parameters specify the step and
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direction pins respectively; this command will configure them in
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digital output mode. The 'invert_step' parameter specifies whether a
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step occurs on a rising edge (invert_step=0) or falling edge
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(invert_step=1). The 'min_stop_interval' implements a safety
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feature - it is checked when the firmware finishes all moves for a
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stepper - if it is non-zero it specifies the minimum number of clock
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ticks since the last step. It is used as a check on the maximum
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stepper velocity that a stepper may have before stopping.
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* config_end_stop oid=%c pin=%c pull_up=%c stepper_oid=%c : This
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command creates an internal "endstop" object. It is used to specify
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the endstop pins and to enable "homing" operations (see the
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end_stop_home command below). The command will configure the
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specified pin in digital input mode. The 'pull_up' parameter
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determines whether hardware provided pullup resistors for the pin
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(if available) will be enabled. The 'stepper_oid' parameter
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specifies the oid of an associated stepper for the given endstop -
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it is used during homing operations.
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Common commands
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===============
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This section lists some commonly used run-time commands. It is likely
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only of interest to developers looking to gain insight into Klippy.
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* schedule_digital_out oid=%c clock=%u value=%c : This command will
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schedule a change to a digital output GPIO pin at the given clock
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time. To use this command a 'config_digital_out' command with the
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same 'oid' parameter must have been issued during firmware
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configuration.
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* schedule_pwm_out oid=%c clock=%u value=%c : Schedules a change to a
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hardware PWM output pin. See the 'schedule_digital_out' and
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'config_pwm_out' commands for more info.
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* schedule_soft_pwm_out oid=%c clock=%u value=%c : Schedules a change
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to a software PWM output pin. See the 'schedule_digital_out' and
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'config_soft_pwm_out' commands for more info.
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* query_analog_in oid=%c clock=%u sample_ticks=%u sample_count=%c
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rest_ticks=%u min_value=%hu max_value=%hu : This command sets up a
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recurring schedule of analog input samples. To use this command a
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'config_analog_in' command with the same 'oid' parameter must have
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been issued during firmware configuration. The samples will start as
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of 'clock' time, it will report on the obtained value every
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'rest_ticks' clock ticks, it will over-sample 'sample_count' number
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of times, and it will pause 'sample_ticks' number of clock ticks
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between over-sample samples. The 'min_value' and 'max_value'
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parameters implement a safety feature - the firmware will verify the
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sampled value (after any oversampling) is always between the
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supplied range. This is intended for use with pins attached to
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thermistors controlling heaters - it can be used to check that a
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heater is within a temperature range.
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* get_status : This command causes the firmware to generate a "status"
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response message. The host sends this command once a second to
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obtain the value of the micro-controller clock and to estimate the
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drift between host and micro-controller clocks. It enables the host
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to accurately estimate the micro-controller clock.
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Stepper commands
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----------------
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* queue_step oid=%c interval=%u count=%hu add=%hi : This command
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schedules 'count' number of steps for the given stepper, with
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'interval' number of clock ticks between each step. The first step
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will be 'interval' number of clock ticks since the last scheduled
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step for the given stepper. If 'add' is non-zero then the interval
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will be adjusted by 'add' amount after each step. This command
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appends the given interval/count/add sequence to a per-stepper
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queue. There may be hundreds of these sequences queued during normal
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operation. New sequence are appended to the end of the queue and as
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each sequence completes its 'count' number of steps it is popped
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from the front of the queue. There may be tens of thousands of steps
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queued in the firmware and every step will have a reliable and
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predictable schedule time.
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* set_next_step_dir oid=%c dir=%c : This command specifies the value
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of the dir_pin that the next queue_step command will use.
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* reset_step_clock oid=%c clock=%u : Normally, step timing is relative
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to the last step for a given stepper. This command resets the clock
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so that the next step is relative to the supplied 'clock' time. The
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host usually only sends this command at the start of a print or
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after a long idle period for the stepper (for example a Z stepper
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move after printing an extensive layer).
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* end_stop_home oid=%c clock=%u rest_ticks=%u pin_value=%c : This
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command is used during stepper "homing" operations. To use this
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command a 'config_end_stop' command with the same 'oid' parameter
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must have been issued during firmware configuration. When invoked,
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the firmware will sample the endstop pin every 'rest_ticks' clock
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ticks and check if it has a value equal to 'pin_value'. If the value
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matches then the movement queue for the associated stepper will be
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cleared and the stepper will come to an immediate halt. The host
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uses this command to implement homing - the host instructs the
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endstop to sample for the endstop trigger and then it issues a
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series of queue_step commands to the stepper to move it towards the
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endstop. Once the stepper hits the endstop, the trigger will be
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detected, the movement halted, and the host notified.
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@ -5,7 +5,9 @@ See [code overview](Code_Overview.md) for developer information on the
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structure and layout of the Klipper code.
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See [protocol](Protocol.md) for developer information on the messaging
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protocol between host and firmware.
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protocol between host and firmware. See also
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[firmware commands](Firmware_Commands.md) for a high-level description
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of some commands implemented in the firmware.
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See [debugging](Debugging.md) for developer information on how to test
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and debug Klipper.
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