diff options
Diffstat (limited to 'pcr-controller/pid_control.c')
| -rw-r--r-- | pcr-controller/pid_control.c | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/pcr-controller/pid_control.c b/pcr-controller/pid_control.c new file mode 100644 index 0000000..ce39bc1 --- /dev/null +++ b/pcr-controller/pid_control.c @@ -0,0 +1,109 @@ +#include "pid_control.h" + +#include <avr/eeprom.h> + +EEMEM int32_t pid_p_eeprom_; +EEMEM int32_t pid_i_eeprom_; +EEMEM int32_t pid_d_eeprom_; +EEMEM int32_t crc_eeprom_; + +#define PID_SCALE 1024L + +int32_t pid_outlimit_min_ = -255 * PID_SCALE; +int32_t pid_outlimit_max_ = 255 * PID_SCALE; + +int32_t pid_p_ = 8192; +int32_t pid_i_ = 512; +int32_t pid_d_ = 24576; + +int32_t pid_i_integralsum_ = 0; +int32_t pid_d_last_error_ = 0; + +uint16_t pid_target_value_ = 0; + +void pid_setP(int16_t p) +{ + pid_p_ = (int32_t) p * PID_SCALE; + pid_saveToEEPROM(); +} + +void pid_setI(int16_t i) +{ + pid_i_ = (int32_t) i * PID_SCALE; + pid_saveToEEPROM(); +} + +void pid_setD(int16_t d) +{ + pid_d_ = (int32_t) d * PID_SCALE; + pid_saveToEEPROM(); +} + +void pid_printVars(void) +{ + printf("PID P: %d\r\nPID I: %d\r\nPID D: %d\r\n", (int16_t) (pid_p_ / PID_SCALE), (int16_t) (pid_i_ / PID_SCALE), (int16_t) (pid_d_ / PID_SCALE)); +} + +void pid_setTargetValue(uint16_t v) +{ + pid_target_value_ = v; +} + +uint16_t pid_getTargetValue(void) +{ + return pid_target_value_; +} + +// PRE-CONDITION: call pid_calc at exactly regular intervals !! +int16_t pid_calc(uint16_t current_value) +{ + int32_t error = pid_target_value_ - current_value; + // derivative + // instead of derivative of error we take derivative on measurement + // since dError/dt = - dInput/dt (note the - ) + int32_t d_measure = current_value - pid_d_last_error_; + pid_d_last_error_ = error; + + // integral (bring pid_i_ into integral, so we get smooth transfer if pid_i_ suddenly changes) + pid_i_integralsum_ += pid_i_ * error; + + // prevent integrator wind-up + if (pid_i_integralsum_ > pid_outlimit_max_) + pid_i_integralsum_ = pid_outlimit_max_; + else if (pid_i_integralsum_ < pid_outlimit_min_) + pid_i_integralsum_ = pid_outlimit_min_; + + // combine factors (insofar as we did not already do it above) + int32_t pid_output_preclamp = ( + (error * pid_p_) + (pid_i_integralsum_) - (d_measure * pid_d_) + ); + + // limit output + if (pid_output_preclamp > pid_outlimit_max_) + return (int16_t) (pid_outlimit_max_ / PID_SCALE); + else if (pid_output_preclamp < pid_outlimit_min_) + return (int16_t) (pid_outlimit_min_ / PID_SCALE); + else + return (int16_t) (pid_output_preclamp / PID_SCALE); +} + +void pid_loadFromEEPROM(void) +{ + int32_t p = eeprom_read_dword((uint32_t *) &pid_p_eeprom_); + int32_t i = eeprom_read_dword((uint32_t *) &pid_i_eeprom_); + int32_t d = eeprom_read_dword((uint32_t *) &pid_d_eeprom_); + int32_t crc = eeprom_read_dword((uint32_t *) &crc_eeprom_); + if (crc == (p ^ i ^ d)) { + pid_p_ = p; + pid_i_ = i; + pid_d_ = d; + } +} + +void pid_saveToEEPROM(void) +{ + eeprom_write_dword((uint32_t *) &pid_p_eeprom_, pid_p_); + eeprom_write_dword((uint32_t *) &pid_i_eeprom_, pid_i_); + eeprom_write_dword((uint32_t *) &pid_d_eeprom_, pid_d_); + eeprom_write_word((uint16_t *) &crc_eeprom_, pid_p_ ^ pid_i_ ^ pid_d_); +}
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