src/temperature/pid.h File Reference

The proportional–integral–derivative algorithm controls the amount of power delivered to the nozzle and printbed heaters, in order to keep them at their required temperature, without too much fluctuation. More...

#include <stdint.h>

Go to the source code of this file.

Data Structures
struct	pid_t
	Datastructure for an instance of the PID algorithm. More...
Functions
void	pid_init (pid_t *pid, uint8_t envelope, uint8_t p, uint8_t i, uint8_t d)
	Initializes an instance of the PID algorithm.
void	pid_set_target (pid_t *pid, float target_temp)
	Sets the target temperature for a given PID algorithm instance.
uint8_t	pid_next (pid_t *pid, float current_temp)
	Returns the next result of a given PID algorithm instance, given the current measured temperature.

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Detailed Description

The proportional–integral–derivative algorithm controls the amount of power delivered to the nozzle and printbed heaters, in order to keep them at their required temperature, without too much fluctuation.

Author:

Pieter Agten (pieter.agten@gmail.com)

Date:

28 okt 2011

Definition in file pid.h.

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Function Documentation

void pid_init	(	pid_t *	pid,
		uint8_t	envelope,
		uint8_t	p,
		uint8_t	i,
		uint8_t	d
	)

Initializes an instance of the PID algorithm.

Parameters:

pid	pointer to the instance of the PID algorithm to initialize
envelope	number of degrees above or below the target temperature, at which the PID algorithm kicks in. Outside of this temperature range, pid_next returns 0 if the temperature is too high and 255 if it is too low.
p	gain of the proportional component for the given PID instance
i	gain of the integral component for the given PID instance
d	gain of the derivative component for the given PID instance

Definition at line 52 of file pid.c.

uint8_t pid_next	(	pid_t *	pid,
		float	current_temp
	)

Returns the next result of a given PID algorithm instance, given the current measured temperature.

The result indicates the amount of power to apply to heater belonging to the given PID instance. This function should be called at short periodic intervals.

Parameters:

pid	pointer to the PID instance for which to return the next result
current_temp	the current measured temperature in degrees celsius

Returns:

An integer between 0 and 255, indicating the relative amount of power to apply to the heater belonging to the given PID instance, in order to reach the instance's target temperature.

Definition at line 74 of file pid.c.

void pid_set_target	(	pid_t *	pid,
		float	target_temp
	)

Sets the target temperature for a given PID algorithm instance.

Parameters:

pid	pointer to the PID instance of which to set the target temperature
target_temp	target temperature in degrees celcius

Definition at line 66 of file pid.c.