README: Add section on using resistive heaters

README.md

@@ -187,32 +187,39 @@ If the Thermostat is used for temperature control with the Sinara 5432 DAC "Zoti
 
 Testing heat flow direction with a low set current is recommended before installation of the TEC module.
 
+## Resistive Heater
+
+When using resistive heaters with the Thermostat, ensure that the thermal load has sufficient cooling, and connect the heater to TEC0- and TEC0+ or TEC1- and TEC1+.
+
+Then, set `max_i_neg` and `output_min` to 0 A with `pwm <ch> max_i_neg 0` and `pid <ch> output_min 0`, and make sure that `output_max` is non-negative.
+
 ### Limits
 
-Each channel has maximum value settings, for setting
+Each MAX1968 TEC driver has analog/PWM inputs for setting
 output limits.
 
-Use the `output` command to see them.
+Use the `output` command to see current settings and maximum values.
 
 | Limit       | Unit    | Description                   |
 | ---         | :---:   | ---                           |
 | `max_v`     | Volts   | Maximum voltage               |
 | `max_i_pos` | Amperes | Maximum positive current      |
 | `max_i_neg` | Amperes | Maximum negative current      |
+| `i_set`     | Amperes | (Not a limit; Open-loop mode) |
 
 Example: set the maximum voltage of channel 0 to 1.5 V.
 ```
 output 0 max_v 1.5
 ```
 
-Example: set the maximum negative current of channel 0 to -2 A.
+Example: set the maximum negative current of channel 0 to -3 A.
 ```
-output 0 max_i_neg 2
+output 0 max_i_neg 3
 ```
 
-Example: set the maximum positive current of channel 1 to 2 A.
+Example: set the maximum positive current of channel 1 to 3 A.
 ```
-output 1 max_i_pos 2
+output 0 max_i_pos 3
 ```
 
 ### Open-loop mode
@@ -239,22 +246,6 @@ of channel 0 to the PID algorithm:
 output 0 pid
 ```
 
-### PID output clamping
-
-It is possible to clamp the PID algorithm output independently of channel output limits. This is desirable when e.g. there is a need to keep the current value above a certain threshold in closed-loop mode.
-
-Note that the actual output will still ultimately be limited by the `max_i_pos` and `max_i_neg` values.
-
-Set PID maximum output of channel 0 to 1.5 A.
-```
-pid 0 output_max 1.5
-```
-
-Set PID minimum output of channel 0 to 0.1 A.
-```
-pid 0 output_min 0.1
-```
-
 ## LED indicators
 
 | Name | Color | Meaning                        |

doc/PID tuning.md

@@ -13,7 +13,7 @@ When tuning Thermostat PID parameters, it is helpful to view the temperature, PI
 To use the Python real-time plotting utility, run
 
 ```shell
-python pythermostat/pythermostat/plot.py
+python pytec/plot.py
 ```
 
 ![default view](./assets/default%20view.png)
@@ -44,12 +44,12 @@ Below are some general guidelines for manually tuning PID loops. Note that every
 
 ## Auto Tuning
 
-A PID auto tuning utility is provided in the PyThermostat library. The auto tuning utility drives the the load to a controlled oscillation, observes the ultimate gain and oscillation period and calculates a set of PID parameters.
+A PID auto tuning utility is provided in the Pytec library. The auto tuning utility drives the the load to a controlled oscillation, observes the ultimate gain and oscillation period and calculates a set of PID parameters.
 
 To run the auto tuning utility, run
 
 ```shell
-python pythermostat/pythermostat/autotune.py
+python pytec/autotune.py
 ```
 
 After some time, the auto tuning utility will output the auto tuning results, below is a sample output

flake.nix

@@ -57,23 +57,10 @@
         dontFixup = true;
         auditable = false;
       };
-
-      pythermostat = pkgs.python3Packages.buildPythonPackage {
-        pname = "pythermostat";
-        version = "0.0.0";
-        format = "pyproject";
-        src = "${self}/pythermostat";
-
-        propagatedBuildInputs =
-          with pkgs.python3Packages; [
-            numpy
-            matplotlib
-          ];
-      };
     in
     {
       packages.x86_64-linux = {
-        inherit thermostat pythermostat;
+        inherit thermostat;
         default = thermostat;
       };
 

pytec/autotune.py

@@ -1,10 +1,9 @@
 import math
 import logging
-import time
 from collections import deque, namedtuple
 from enum import Enum
 
-from pythermostat.client import Client
+from pytec.client import Client
 
 # Based on hirshmann pid-autotune libiary
 # See https://github.com/hirschmann/pid-autotune
@@ -237,14 +236,13 @@ def main():
 
     tec = Client()
 
-    data = tec.get_report()
+    data = next(tec.report_mode())
     ch = data[channel]
 
     tuner = PIDAutotune(target_temperature, output_step,
                         lookback, noiseband, ch['interval'])
 
-    while True:
+    for data in tec.report_mode():
-        data = tec.get_report()
 
         ch = data[channel]
 
@@ -257,8 +255,6 @@ def main():
 
         tec.set_param("output", channel, "i_set", tuner_out)
 
-        time.sleep(0.05)
-
     tec.set_param("output", channel, "i_set", 0)
 
 

pytec/example.py

@@ -1,5 +1,4 @@
-import time
+from pytec.client import Client
-from pythermostat.client import Client
 
 tec = Client() #(host="localhost", port=6667)
 tec.set_param("b-p", 1, "t0", 20)
@@ -8,6 +7,5 @@ print(tec.get_pid())
 print(tec.get_output())
 print(tec.get_postfilter())
 print(tec.get_b_parameter())
-while True:
+for data in tec.report_mode():
-    print(tec.get_report())
+    print(data)
-    time.sleep(0.05)

pytec/plot.py

@@ -0,0 +1,128 @@
+import numpy as np
+import matplotlib.pyplot as plt
+import matplotlib.animation as animation
+from threading import Thread, Lock
+from pytec.client import Client
+
+TIME_WINDOW = 300.0
+
+tec = Client()
+target_temperature = tec.get_pid()[0]['target']
+print("Channel 0 target temperature: {:.3f}".format(target_temperature))
+
+class Series:
+    def __init__(self, conv=lambda x: x):
+        self.conv = conv
+        self.x_data = []
+        self.y_data = []
+
+    def append(self, x, y):
+        self.x_data.append(x)
+        self.y_data.append(self.conv(y))
+
+    def clip(self, min_x):
+        drop = 0
+        while drop < len(self.x_data) and self.x_data[drop] < min_x:
+            drop += 1
+        self.x_data = self.x_data[drop:]
+        self.y_data = self.y_data[drop:]
+        
+series = {
+    # 'adc': Series(),
+    # 'sens': Series(lambda x: x * 0.0001),
+    'temperature': Series(),
+    # 'i_set': Series(),
+    'pid_output': Series(),
+    # 'vref': Series(),
+    # 'dac_value': Series(),
+    # 'dac_feedback': Series(),
+    # 'i_tec': Series(),
+    'tec_i': Series(),
+    'tec_u_meas': Series(),
+    # 'interval': Series(),
+}
+series_lock = Lock()
+
+quit = False
+
+def recv_data(tec):
+    global last_packet_time
+    for data in tec.report_mode():
+        ch0 = data[0]
+        series_lock.acquire()
+        try:
+            for k, s in series.items():
+                if k in ch0:
+                    v = ch0[k]
+                    if type(v) is float:
+                        s.append(ch0['time'], v)
+        finally:
+            series_lock.release()
+
+        if quit:
+            break
+
+thread = Thread(target=recv_data, args=(tec,))
+thread.start()
+
+fig, ax = plt.subplots()
+
+for k, s in series.items():
+    s.plot, = ax.plot([], [], label=k)
+legend = ax.legend()
+
+def animate(i):
+    min_x, max_x, min_y, max_y = None, None, None, None
+    
+    series_lock.acquire()
+    try:
+        for k, s in series.items():
+            s.plot.set_data(s.x_data, s.y_data)
+            if len(s.y_data) > 0:
+                s.plot.set_label("{}: {:.3f}".format(k, s.y_data[-1]))
+
+            if len(s.x_data) > 0:
+                min_x_ = min(s.x_data)
+                if min_x is None:
+                    min_x = min_x_
+                else:
+                    min_x = min(min_x, min_x_)
+                max_x_ = max(s.x_data)
+                if max_x is None:
+                    max_x = max_x_
+                else:
+                    max_x = max(max_x, max_x_)
+            if len(s.y_data) > 0:
+                min_y_ = min(s.y_data)
+                if min_y is None:
+                    min_y = min_y_
+                else:
+                    min_y = min(min_y, min_y_)
+                max_y_ = max(s.y_data)
+                if max_y is None:
+                    max_y = max_y_
+                else:
+                    max_y = max(max_y, max_y_)
+
+        if min_x and max_x - TIME_WINDOW > min_x:
+            for s in series.values():
+                s.clip(max_x - TIME_WINDOW)
+    finally:
+        series_lock.release()
+
+    if min_x != max_x:
+        ax.set_xlim(min_x, max_x)
+    if min_y != max_y:
+        margin_y = 0.01 * (max_y - min_y)
+        ax.set_ylim(min_y - margin_y, max_y + margin_y)
+
+    global legend
+    legend.remove()
+    legend = ax.legend()
+
+ani = animation.FuncAnimation(
+    fig, animate, interval=1, blit=False, save_count=50)
+
+plt.show()
+quit = True
+thread.join()

pytec/pytec/client.py

@@ -1,7 +1,7 @@
 import socket
 import json
 import logging
-
+import time
 
 class CommandError(Exception):
     pass
@@ -147,6 +147,36 @@ class Client:
         """Get Thermostat hardware revision"""
         return self._command("hwrev")
 
+    def report_mode(self):
+        """Start reporting measurement values
+
+        Example of yielded data::
+            {'channel': 0,
+             'time': 2302524,
+             'adc': 0.6199188965423515,
+             'sens': 6138.519310282602,
+             'temperature': 36.87032392655527,
+             'pid_engaged': True,
+             'i_set': 2.0635816680889123,
+             'vref': 1.494,
+             'dac_value': 2.527790834044456,
+             'dac_feedback': 2.523,
+             'i_tec': 2.331,
+             'tec_i': 2.0925,
+             'tec_u_meas': 2.5340000000000003,
+             'pid_output': 2.067581958092247}
+        """
+        while True:
+            self._socket.sendall("report\n".encode('utf-8'))
+            line = self._read_line()
+            if not line:
+                break
+            try:
+                yield json.loads(line)
+            except json.decoder.JSONDecodeError:
+                pass
+            time.sleep(0.05)
+
     def set_param(self, topic, channel, field="", value=""):
         """Set configuration parameters
 

pytec/setup.py

@@ -0,0 +1,12 @@
+from setuptools import setup, find_packages
+
+setup(
+    name="pytec",
+    version="0.0",
+    author="M-Labs",
+    url="https://git.m-labs.hk/M-Labs/thermostat",
+    description="Control TEC",
+    license="GPLv3",
+    install_requires=["setuptools"],
+    packages=find_packages(),
+)

pythermostat/pyproject.toml

@@ -1,18 +0,0 @@
-[build-system]
-requires = ["setuptools"]
-build-backend = "setuptools.build_meta"
-
-[project]
-name = "pythermostat"
-version = "0.0"
-authors = [{name = "M-Labs"}]
-description = "Python utilities for the Sinara 8451 Thermostat"
-urls.Repository = "https://git.m-labs.hk/M-Labs/thermostat"
-license = {text = "GPLv3"}
-
-[project.gui-scripts]
-thermostat_plot = "pythermostat.plot:main"
-
-[project.scripts]
-thermostat_autotune = "pythermostat.autotune:main"
-thermostat_test = "pythermostat.test:main"

pythermostat/pythermostat/plot.py

@@ -1,137 +0,0 @@
-import time
-import numpy as np
-import matplotlib.pyplot as plt
-import matplotlib.animation as animation
-from threading import Thread, Lock
-from pythermostat.client import Client
-
-
-def main():
-    TIME_WINDOW = 300.0
-
-    tec = Client()
-    target_temperature = tec.get_pid()[0]['target']
-    print("Channel 0 target temperature: {:.3f}".format(target_temperature))
-
-    class Series:
-        def __init__(self, conv=lambda x: x):
-            self.conv = conv
-            self.x_data = []
-            self.y_data = []
-
-        def append(self, x, y):
-            self.x_data.append(x)
-            self.y_data.append(self.conv(y))
-
-        def clip(self, min_x):
-            drop = 0
-            while drop < len(self.x_data) and self.x_data[drop] < min_x:
-                drop += 1
-            self.x_data = self.x_data[drop:]
-            self.y_data = self.y_data[drop:]
-
-    series = {
-        # 'adc': Series(),
-        # 'sens': Series(lambda x: x * 0.0001),
-        'temperature': Series(),
-        # 'i_set': Series(),
-        'pid_output': Series(),
-        # 'vref': Series(),
-        # 'dac_value': Series(),
-        # 'dac_feedback': Series(),
-        # 'i_tec': Series(),
-        'tec_i': Series(),
-        'tec_u_meas': Series(),
-        # 'interval': Series(),
-    }
-    series_lock = Lock()
-
-    quit = False
-
-    def recv_data(tec):
-        global last_packet_time
-        while True:
-            data = tec.get_report()
-            ch0 = data[0]
-            series_lock.acquire()
-            try:
-                for k, s in series.items():
-                    if k in ch0:
-                        v = ch0[k]
-                        if type(v) is float:
-                            s.append(ch0['time'], v)
-            finally:
-                series_lock.release()
-
-            if quit:
-                break
-            time.sleep(0.05)
-
-    thread = Thread(target=recv_data, args=(tec,))
-    thread.start()
-
-    fig, ax = plt.subplots()
-
-    for k, s in series.items():
-        s.plot, = ax.plot([], [], label=k)
-    legend = ax.legend()
-
-    def animate(i):
-        min_x, max_x, min_y, max_y = None, None, None, None
-        
-        series_lock.acquire()
-        try:
-            for k, s in series.items():
-                s.plot.set_data(s.x_data, s.y_data)
-                if len(s.y_data) > 0:
-                    s.plot.set_label("{}: {:.3f}".format(k, s.y_data[-1]))
-
-                if len(s.x_data) > 0:
-                    min_x_ = min(s.x_data)
-                    if min_x is None:
-                        min_x = min_x_
-                    else:
-                        min_x = min(min_x, min_x_)
-                    max_x_ = max(s.x_data)
-                    if max_x is None:
-                        max_x = max_x_
-                    else:
-                        max_x = max(max_x, max_x_)
-                if len(s.y_data) > 0:
-                    min_y_ = min(s.y_data)
-                    if min_y is None:
-                        min_y = min_y_
-                    else:
-                        min_y = min(min_y, min_y_)
-                    max_y_ = max(s.y_data)
-                    if max_y is None:
-                        max_y = max_y_
-                    else:
-                        max_y = max(max_y, max_y_)
-
-            if min_x and max_x - TIME_WINDOW > min_x:
-                for s in series.values():
-                    s.clip(max_x - TIME_WINDOW)
-        finally:
-            series_lock.release()
-
-        if min_x != max_x:
-            ax.set_xlim(min_x, max_x)
-        if min_y != max_y:
-            margin_y = 0.01 * (max_y - min_y)
-            ax.set_ylim(min_y - margin_y, max_y + margin_y)
-
-        nonlocal legend
-        legend.remove()
-        legend = ax.legend()
-
-    ani = animation.FuncAnimation(
-        fig, animate, interval=1, blit=False, save_count=50)
-
-    plt.show()
-    quit = True
-    thread.join()
-
-
-if __name__ == "__main__":
-    main()

pythermostat/pythermostat/test.py

@@ -1,81 +0,0 @@
-import argparse
-from contextlib import contextmanager
-from pythermostat.client import Client
-
-
-CHANNELS = 2
-
-
-def get_argparser():
-    parser = argparse.ArgumentParser(description="Thermostat hardware testing script")
-
-    parser.add_argument("host", metavar="HOST", default="192.168.1.26", nargs="?")
-    parser.add_argument("port", metavar="PORT", default=23, nargs="?")
-    parser.add_argument(
-        "-r",
-        "--testing_resistance",
-        default=10_000,
-        help="Testing resistance value through SENS pin in Ohms",
-    )
-    parser.add_argument(
-        "-d",
-        "--deviation",
-        default=1,
-        help="Allowed deviation of resistance in percentage",
-    )
-
-    return parser
-
-
-def main():
-    args = get_argparser().parse_args()
-
-    min_allowed_resistance = args.testing_resistance * (1 - args.deviation / 100)
-    max_allowed_resistance = args.testing_resistance * (1 + args.deviation / 100)
-
-    print(min_allowed_resistance, max_allowed_resistance)
-
-    thermostat = Client(args.host, args.port)
-    for channel in range(CHANNELS):
-        print(f"Channel {channel} is active")
-
-        print("Checking resistance through SENS input ....", end=" ")
-        sens_resistance = thermostat.get_report()[channel]["sens"]
-        if sens_resistance is not None:
-            print(sens_resistance, "Ω")
-            if min_allowed_resistance <= sens_resistance <= max_allowed_resistance:
-                print("PASSED")
-            else:
-                print("FAILED")
-        else:
-            print("Floating SENS input! Is the channel connected?")
-
-        with preserve_thermostat_output_settings(thermostat, channel):
-            test_output_settings = {
-                "max_i_pos": 2,
-                "max_i_neg": 2,
-                "max_v": 4,
-                "i_set": 0.1,
-                "polarity": "normal",
-            }
-            for field, value in test_output_settings.items():
-                thermostat.set_param("output", channel, field, value)
-
-            input(f"Check if channel {channel} current = 0.1 A, and press ENTER...")
-
-        input(f"Channel {channel} testing done, press ENTER to continue.")
-        print()
-
-    print("Testing complete.")
-
-
-@contextmanager
-def preserve_thermostat_output_settings(client, channel):
-    original_output_settings = client.get_output()[channel]
-    yield original_output_settings
-    for setting in "max_i_pos", "max_i_neg", "max_v", "i_set", "polarity":
-        client.set_param("output", channel, setting, original_output_settings[setting])
-
-
-if __name__ == "__main__":
-    main()