pid_calibrate: Move PID calibration logic from heater.py to new file

Drop support for M303 and PID_TUNE, and replace it with a new
PID_CALIBRATE command.  Move the logic for this command from heater.py
to a new pid_calibrate.py file in the extras/ directory.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/extras/pid_calibrate.py

@@ -0,0 +1,127 @@
+# Calibration of heater PID settings
+#
+# Copyright (C) 2016-2018  Kevin O'Connor <kevin@koconnor.net>
+#
+# This file may be distributed under the terms of the GNU GPLv3 license.
+import math, logging
+import extruder, heater
+
+class PIDCalibrate:
+    def __init__(self, config):
+        self.printer = config.get_printer()
+        self.gcode = self.printer.lookup_object('gcode')
+        self.gcode.register_command(
+            'PID_CALIBRATE', self.cmd_PID_CALIBRATE,
+            desc=self.cmd_PID_CALIBRATE_help)
+    cmd_PID_CALIBRATE_help = "Run PID calibration test"
+    def cmd_PID_CALIBRATE(self, params):
+        heater_name = self.gcode.get_str('HEATER', params)
+        target = self.gcode.get_float('TARGET', params)
+        write_file = self.gcode.get_int('WRITE_FILE', params, 0)
+        try:
+            heater = extruder.get_printer_heater(self.printer, heater_name)
+        except self.printer.config_error as e:
+            raise self.gcode.error(str(e))
+        print_time = self.printer.lookup_object('toolhead').get_last_move_time()
+        calibrate = ControlAutoTune(heater)
+        old_control = heater.set_control(calibrate)
+        try:
+            heater.set_temp(print_time, target)
+        except heater.error as e:
+            raise self.gcode.error(str(e))
+        self.gcode.bg_temp(heater)
+        heater.set_control(old_control)
+        if write_file:
+            calibrate.write_file('/tmp/heattest.txt')
+        Kp, Ki, Kd = calibrate.calc_final_pid()
+        logging.info("Autotune: final: Kp=%f Ki=%f Kd=%f", Kp, Ki, Kd)
+        self.gcode.respond_info(
+            "PID parameters: pid_Kp=%.3f pid_Ki=%.3f pid_Kd=%.3f\n"
+            "To use these parameters, update the printer config file with\n"
+            "the above and then issue a RESTART command" % (Kp, Ki, Kd))
+
+TUNE_PID_DELTA = 5.0
+
+class ControlAutoTune:
+    def __init__(self, heater):
+        self.heater = heater
+        # Heating control
+        self.heating = False
+        self.peak = 0.
+        self.peak_time = 0.
+        # Peak recording
+        self.peaks = []
+        # Sample recording
+        self.last_pwm = 0.
+        self.pwm_samples = []
+        self.temp_samples = []
+    # Heater control
+    def set_pwm(self, read_time, value):
+        if value != self.last_pwm:
+            self.pwm_samples.append((read_time + heater.PWM_DELAY, value))
+            self.last_pwm = value
+        self.heater.set_pwm(read_time, value)
+    def adc_callback(self, read_time, temp):
+        self.temp_samples.append((read_time, temp))
+        if self.heating and temp >= self.heater.target_temp:
+            self.heating = False
+            self.check_peaks()
+        elif (not self.heating
+              and temp <= self.heater.target_temp - TUNE_PID_DELTA):
+            self.heating = True
+            self.check_peaks()
+        if self.heating:
+            self.set_pwm(read_time, self.heater.max_power)
+            if temp < self.peak:
+                self.peak = temp
+                self.peak_time = read_time
+        else:
+            self.set_pwm(read_time, 0.)
+            if temp > self.peak:
+                self.peak = temp
+                self.peak_time = read_time
+    def check_busy(self, eventtime):
+        if self.heating or len(self.peaks) < 12:
+            return True
+        return False
+    # Analysis
+    def check_peaks(self):
+        self.peaks.append((self.peak, self.peak_time))
+        if self.heating:
+            self.peak = 9999999.
+        else:
+            self.peak = -9999999.
+        if len(self.peaks) < 4:
+            return
+        self.calc_pid(len(self.peaks)-1)
+    def calc_pid(self, pos):
+        temp_diff = self.peaks[pos][0] - self.peaks[pos-1][0]
+        time_diff = self.peaks[pos][1] - self.peaks[pos-2][1]
+        max_power = self.heater.max_power
+        Ku = 4. * (2. * max_power) / (abs(temp_diff) * math.pi)
+        Tu = time_diff
+
+        Ti = 0.5 * Tu
+        Td = 0.125 * Tu
+        Kp = 0.6 * Ku * heater.PID_PARAM_BASE
+        Ki = Kp / Ti
+        Kd = Kp * Td
+        logging.info("Autotune: raw=%f/%f Ku=%f Tu=%f  Kp=%f Ki=%f Kd=%f",
+                     temp_diff, max_power, Ku, Tu, Kp, Ki, Kd)
+        return Kp, Ki, Kd
+    def calc_final_pid(self):
+        cycle_times = [(self.peaks[pos][1] - self.peaks[pos-2][1], pos)
+                       for pos in range(4, len(self.peaks))]
+        midpoint_pos = sorted(cycle_times)[len(cycle_times)/2][1]
+        return self.calc_pid(midpoint_pos)
+    # Offline analysis helper
+    def write_file(self, filename):
+        pwm = ["pwm: %.3f %.3f" % (time, value)
+               for time, value in self.pwm_samples]
+        out = ["%.3f %.3f" % (time, temp) for time, temp in self.temp_samples]
+        f = open(filename, "wb")
+        f.write('\n'.join(pwm + out))
+        f.close()
+
+def load_config(config):
+    return PIDCalibrate(config)