55 lines
1.7 KiB
C
55 lines
1.7 KiB
C
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/**
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* General PID implementation for AVR
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*
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* Discrete PID controller implementation. Set up by giving P/I/D terms
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* to pid_init(), and uses a struct pid to store internal values.
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*
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* Based on ATMEL AppNote: AVR221 - Discrete PID controller
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*
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* @copyright 2012 Institute Automation of Complex Power Systems (ACS), RWTH Aachen University
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* @license http://www.gnu.org/licenses/gpl.txt GNU Public License
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* @author Atmel Corporation <avr@atmel.com>
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* @link http://www.atmel.com
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* @revision 456
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* @date 2006-02-16 12:46:13
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*/
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#ifndef _PID_H_
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#define _PID_H_
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#include <stdlib.h>
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#include <stdint.h>
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#define SCALING_FACTOR 128
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#define SCALING_SHIFT 7
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/**
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* PID Status
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*
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* Setpoints and data used by the PID control algorithm
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*/
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struct pid {
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int16_t lastProcessValue; // Last process value, used to find derivative of process value.
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int32_t sumError; // Summation of errors, used for integrate calculations
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int16_t pFactor; // The Proportional tuning constant, multiplied with SCALING_FACTOR
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int16_t iFactor; // The Integral tuning constant, multiplied with SCALING_FACTOR
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int16_t dFactor; // The Derivative tuning constant, multiplied with SCALING_FACTOR
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int16_t maxError; // Maximum allowed error, avoid overflow
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int32_t maxSumError; // Maximum allowed sumerror, avoid overflow
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};
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/**
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* Maximum values
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*
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* Needed to avoid sign/overflow problems
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*/
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#define MAX_INT INT16_MAX
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#define MAX_LONG INT32_MAX
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#define MAX_I_TERM (MAX_LONG / 2)
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void pid_init(int16_t pFactor, int16_t iFactor, int16_t dFactor, struct pid *pid);
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int16_t pid_controller(int16_t setPoint, int16_t processValue, struct pid *pid);
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void pid_reset_integrator(struct pid *pid);
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#endif /* _PID_H_ */
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