heater.c File Reference

Manage heaters. More...

#include "heater.h"
#include <stdlib.h>
#include <avr/eeprom.h>
#include <avr/pgmspace.h>
#include "arduino.h"
#include "debug.h"
#include "temp.h"
#include "crc.h"
#include "sersendf.h"
#include "config.h"

Data Structures
struct	heater_definition_t
	simply holds pinout data- port, pin, pwm channel if used More...
struct	EE_factor
	this lives in the eeprom so we can save our PID settings for each heater More...
Defines
#define	DEFINE_HEATER(name, port, pin, pwm)   { &(port), (pin), &(pwm) },
	helper macro to fill heater definition struct from config.h
#define	DEFAULT_P   8192
	default scaled P factor, equivalent to 8.0
#define	DEFAULT_I   512
	default scaled I factor, equivalent to 0.5
#define	DEFAULT_D   24576
	default scaled D factor, equivalent to 24
#define	DEFAULT_I_LIMIT   384
	default scaled I limit
Functions
void	heater_init ()
	initialise heater subsystem Set directions, initialise PWM timers, read PID factors from eeprom, etc
void	heater_save_settings ()
	Write PID factors to eeprom.
void	heater_tick (heater_t h, temp_sensor_t t, uint16_t current_temp, uint16_t target_temp)
	run heater PID algorithm
void	heater_set (heater_t index, uint8_t value)
	manually set PWM output
uint8_t	heaters_all_off ()
	turn off all heaters
void	pid_set_p (heater_t index, int32_t p)
	set heater P factor
void	pid_set_i (heater_t index, int32_t i)
	set heater I factor
void	pid_set_d (heater_t index, int32_t d)
	set heater D factor
void	pid_set_i_limit (heater_t index, int32_t i_limit)
	set heater I limit
void	heater_print (uint16_t i)
	send heater debug info to host
Variables
struct {
int32_t   p_factor
	scaled P factor
int32_t   i_factor
	scaled I factor
int32_t   d_factor
	scaled D factor
int16_t   i_limit
	scaled I limit, such that
}	heaters_pid [NUM_HEATERS]
	this struct holds the heater PID factors
struct {
int16_t   heater_i
	integrator,
uint16_t   temp_history [TH_COUNT]
	store last TH_COUNT readings in a ring, so we can smooth out our differentiator
uint8_t   temp_history_pointer
	pointer to last entry in ring
uint8_t   heater_output
	this is the PID value we eventually send to the heater
}	heaters_runtime [NUM_HEATERS]
EE_factor EEMEM	EE_factors [NUM_HEATERS]

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Detailed Description

Manage heaters.

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Function Documentation

void heater_print

(

uint16_t

i )

send heater debug info to host

Parameters:

i	index of heater to send info for

Referenced by process_gcode_command().

void heater_set	(	heater_t	index,
		uint8_t	value
	)

manually set PWM output

Parameters:

index	the heater we're setting the output for
value	the PWM value to write

anything done by this function is overwritten by heater_tick above if the heater has an associated temp sensor

Referenced by dda_start(), dda_step(), heater_tick(), and process_gcode_command().

void heater_tick	(	heater_t	h,
		temp_sensor_t	t,
		uint16_t	current_temp,
		uint16_t	target_temp
	)

run heater PID algorithm

Parameters:

h	which heater we're running the loop for
t	which temp sensor this heater is attached to
current_temp	the temperature that the associated temp sensor is reporting
target_temp	the temperature we're trying to achieve

Referenced by temp_sensor_tick().

uint8_t heaters_all_off

(

void

)

turn off all heaters

for emergency stop

Referenced by clock_250ms().

void pid_set_d	(	heater_t	index,
		int32_t	d
	)

set heater D factor

Parameters:

index	heater to change D factor for
d	scaled D factor

Referenced by process_gcode_command().

void pid_set_i	(	heater_t	index,
		int32_t	i
	)

set heater I factor

Parameters:

index	heater to change I factor for
i	scaled I factor

Referenced by process_gcode_command().

void pid_set_i_limit	(	heater_t	index,
		int32_t	i_limit
	)

set heater I limit

Parameters:

index	heater to set I limit for
i_limit	scaled I limit

Referenced by process_gcode_command().

void pid_set_p	(	heater_t	index,
		int32_t	p
	)

set heater P factor

Parameters:

index	heater to change factor for
p	scaled P factor

Referenced by process_gcode_command().

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Variable Documentation

heaters_pid

this struct holds the heater PID factors

PID is a fascinating way to control any closed loop control, combining the error (P), cumulative error (I) and rate at which we're approacing the setpoint (D) in such a way that when correctly tuned, the system will achieve target temperature quickly and with little to no overshoot

At every sample, we calculate where S is setpoint and T is temperature.

The three factors kP, kI, kD are chosen to give the desired behaviour given the dynamics of the system.

See http://www.eetimes.com/design/embedded/4211211/PID-without-a-PhD for the full story

Referenced by heater_init(), heater_print(), heater_save_settings(), heater_tick(), pid_set_d(), pid_set_i(), pid_set_i_limit(), and pid_set_p().