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bc94075df9 README: Add section on using resistive heaters 2024-11-11 18:04:28 +08:00
12 changed files with 194 additions and 288 deletions

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@ -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 |

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@ -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

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@ -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;
};

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@ -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:
data = tec.get_report()
for data in tec.report_mode():
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)

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@ -1,5 +1,4 @@
import time
from pythermostat.client import Client
from pytec.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:
print(tec.get_report())
time.sleep(0.05)
for data in tec.report_mode():
print(data)

128
pytec/plot.py Normal file
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@ -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()

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@ -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

12
pytec/setup.py Normal file
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@ -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(),
)

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@ -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"

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@ -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()

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@ -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()