Multiwii Write Miscellaneous

Writes miscellaneous information from the auto-pilot, such as thresholds, triggers and counters.

Library

QUARC Targets/Communications/Multiwii

Description

The Multiwii Write Miscellaneous block uses the Multiwii protocol on the input stream to send a command to the aircraft to write miscellaneous information to the auto-pilot. The Multiwii Write Miscellaneous block sends a MSP_SET_MISC message to the auto-pilot.

This block is designed to be used with blocking I/O. It is typically used with a stream connected to a serial port. To open the stream a Multiwii Connect block should be used.

The inputs to the block are the internal power trigger level, throttle thresholds, arm counter and lifetime, magnetic declination, battery voltage scale factor and battery thresholds. The throttle thresholds are input as a 4-vector containing the minimum throttle, maximum throttle, minimum command (throttle at the lowest position), and failsafe threshold for the throttle respectively. The battery thresholds are input as a 3-vector containing the warning level 1, warning level 2 and critical levels respectively. To get the magnetic declination for a particular location, visit https://www.magnetic-declination.com/.

A copy of the stream is also output so that the Multiwii blocks may be chained together.

If an error occurs, then the block returns a negative error code at its err output. The Compare to Error block may be used to check for specific error codes. If the stream is not valid because it is not yet connected, the err output will be zero since this condition is expected and the validity of the stream may be checked using the con output of the Multiwii Connect block.

Helpful Hints

Other uses of this block

Although it is intended for use in the main diagram with the other Multiwii blocks, the Multiwii Write Miscellaneous block may be used with the Advanced stream blocks, even in an asynchronous thread.

Input Ports

stm

A reference to the stream created by the Multiwii Connect block. If a connection has not yet been established, then the err output of the Multiwii Write Miscellaneous block will be zero.

pwr

An integer scalar (uint16) representing the internal power trigger.

thr

A 4-vector of doubles containing the minimum throttle, maximum throttle, minimum command (throttle at the lowest position), and failsafe threshold for the throttle respectively. The values are denoted as percentages between 0 and 1.

arm

An integer scalar (uint16) representing the arm counter.

life

An integer scalar (uint32) representing the lifetime.

mag

A scalar representing the magnetic declination in radians.

scale

An integer scalar (uint8) representing the battery voltage scale factor.

level

A 3-vector of doubles containing the warning level 1, warning level 2 and critical voltage levels for the battery respectively. The units are in Volts.

Output Ports

stm

A reference to the stream. This output is merely a copy of the stm input. Providing this output makes it much easier to establish the execution order of Multiwii blocks in the diagram because Simulink generally executes daisy-chained blocks in sequence.

err

An int32 value indicating whether the message was sent successfully. This value will be positive if message was sent successfully. It will be zero if no message was sent. If an error occurs then this value is a negative error code. See Error Codes for the different error codes and their values. Use the Compare to Error block rather than the error code itself to check for specific error codes. To check for errors in general use the Compare to Zero block to check whether the err output is less than zero.

Parameters and Dialog Box

Write only when the input changes

Check this option to have the block only write new miscellaneous information when the input changes. If this option is not checked then the block will write new miscellaneous information every time it executes.

This option makes it easier to use the block, since it typically makes a Triggered Subsystem unnecessary when the option is checked.

Targets

See Also

• Multiwii Connect block
• Multiwii Communications

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