An electronic thermometer can be made using a temperature sensor, an electronic circuit to process its signal, and a display to show the readings. The sensor is connected to the circuit, then the device is assembled and tested to see how it measures temperature.
In this article, “Technology 2: How to Make an Electronic Thermometer,” we’ll look at how this kind of device works and the sequence for assembling it. This will help explain the parts a thermometer consists of and how they work together.
| Design | Confirmed feature | What is not specified |
|---|---|---|
| PIC16F628A thermometer | Memory for maximum and minimum temperatures | Circuit, sensor, and firmware text |
| Multichannel thermometer | Monitoring up to 15 locations | Sensor and pinout details |
| Dallas Semiconductor sensors | Data transmission over a two-wire cable | Specific model and cable length |
- PIC16F628A Microcontroller in the description of a digital thermometer with maximum and minimum memory
- 15 locations Number of monitoring points in the multichannel thermometer described
- 2 wires Data cable from Dallas Semiconductor sensors to the bus master, according to the source description
What can be reliably said about the microcontroller-based thermometer project?
What the original projects confirm
Project descriptions confirm that the PIC16F628A thermometer stores the highest and lowest measured temperatures, while a separate design is intended to monitor 15 locations. These examples show two different approaches: storing extreme readings and measuring across multiple channels.
- PIC16F628A: a digital thermometer with memory for maximum and minimum temperatures.
- Multichannel project: temperature monitoring at 15 locations.
These descriptions do not provide a complete circuit for a simple single-channel device, a parts list, or assembly instructions. They therefore cannot be used to reconstruct a verified set of instructions, even if the goal is to build just one channel.
The source information also does not identify a specific sensor model, display type, firmware, or calibration values. These parameters cannot be supplied as ready-made solutions: without them, it is impossible to determine the device’s components and how to configure its readings with confidence.
How do you divide a thermometer into a sensor, microcontroller, and display?
An electronic thermometer has three main parts: the sensor measures the temperature, the microcontroller processes the signal, and the display shows the result. In a PIC16F628A-based design, the firmware must read the sensor and send the readings to the display; the available project description does not include the program code.
What to check before connecting the parts
Before connecting anything, consult the documentation for the specific sensor you have chosen: identify its output type, pinout, and communication method. Without this information, it is impossible to determine reliably how to connect the sensor to the PIC16F628A or how the microcontroller will receive its readings.
The display must also be selected before drawing up the circuit: until the sensor and display models are known, it is not possible to specify connections, supply voltage, or component values reliably. This is especially important for a PIC16F628A project: the microcontroller’s name alone does not determine the characteristics of the other components. Another project description mentions a multichannel thermometer for monitoring temperature at 15 locations, but that does not define the circuit for a single-sensor device or replace the documentation for specific components.
How do you connect the sensor and display without guessing the pinout?
Connect the sensor and display only after checking the markings and power requirements against the documentation for the specific components you have chosen; there is no universal pinout here. The device is based on a PIC16F628A microcontroller, but the available information does not identify the sensor model, so you cannot assign pins or choose a supply voltage without checking.
First find out which interface the sensor uses, then check whether the PIC16F628A supports it and whether the firmware can update the readings. The multichannel thermometer description mentions temperature monitoring at up to 15 locations, but it does not specify a sensor interface for this circuit; that number does not replace a compatibility check for the specific components.
Display and connection checks
Determine the display’s pinout and data format separately: the source information does not specify the screen model or its interface. Before applying power, check the connections against the documentation for the PIC16F628A, sensor, and display; if the necessary circuit diagrams and specifications are unavailable, do not connect the device by guesswork.
How do you check the readings and calibrate the thermometer?
Check the electronic thermometer’s readings by comparing them with another thermometer in the same place and under the same conditions. If necessary, calibrate it in software, if the firmware allows this. Record both readings and repeat the comparison after they have stabilized. The source material does not specify an acceptable margin of error, so do not treat an arbitrary accuracy threshold as an established standard.
Compare readings from the two devices at the same point, not results taken in different places or at different times. If the firmware supports adjustment, make the change in the program and compare the readings again after they stabilize; the source descriptions do not provide calibration coefficients.
Checking maximum and minimum memory
For the PIC16F628A version, check separately that the maximum- and minimum-temperature memory updates when the readings change accordingly. Compare the current temperature with the stored maximum and minimum: when a new maximum is reached, the maximum value should change; when a new minimum is reached, the minimum should change.
- Comparing readings: test the assembled thermometer and a second device in the same place and under the same conditions; no specific tolerance is given.
- Checking memory: for the PIC16F628A version, verify that the maximum and minimum are updated separately when the temperature changes in the corresponding direction.
How does a single-channel thermometer differ from monitoring 15 locations?
A single-channel thermometer measures the temperature at one point, while the multichannel project allows it to be monitored at 15 locations at once. Those 15 points are the limit of the project described, not a universal feature of all thermometers.
- Single-channel build: one measurement channel serves one measuring point. This option is suitable when you only need to monitor the temperature in one place.
- Multichannel project: monitoring at up to 15 locations is described. This makes it possible to compare temperatures at several points, but it does not mean every multichannel thermometer supports exactly 15 sensors.
How readings from Dallas sensors are transmitted
An article about Dallas Semiconductor digital sensors describes data being transmitted from the sensors to the bus master over a two-wire cable: the signal travels one way on one wire and returns on the other. This explains the communication principle between distributed sensors and the master device, but it does not specify a universal circuit for a 15-point project.
The descriptions provided do not identify a specific Dallas sensor model, cable length, or connection diagram. These parameters therefore cannot be treated as established: they must be confirmed for the chosen project and components, and the limit of 15 locations applies only to the multichannel thermometer described.
When might this build fail or need modification?
A PIC16F628A build will not work reliably if the sensor model and pinout are unknown: the connection cannot be determined safely from a general description. Before applying power, identify the exact sensor and its pin locations; the source material does not provide information about a specific model.
Even with the connections correct, the display will not show the temperature without compatible firmware: the project description does not include verified, ready-to-use code. The maximum- and minimum-temperature memory mentioned applies specifically to the PIC16F628A thermometer, not to every microcontroller. For another platform, this feature will need to be implemented separately in software.
When a multichannel modification is needed
A single-channel build cannot be treated as a 15-point thermometer without modification: it needs suitable sensors and support for polling multiple channels. The multichannel project description specifies temperature monitoring at up to 15 locations, but that is not enough to transfer its hardware or program automatically to the PIC16F628A. Before assembly, check the model and connections of each sensor, and confirm that the firmware can poll multiple channels.
Frequently asked questions
Can you build a thermometer using a PIC16F628A?
How many points does the multichannel project measure?
How do you connect Dallas Semiconductor sensors?
How can you tell if a homemade thermometer is calibrated correctly?
Sources
- sami-svoimi-rukami.ru — “Making a Simple Microcontroller Thermometer”
- habr.com — “Digital Thermometer Using Discrete Logic”
- pichobbi.narod.ru — “PIC16F628A Microcontroller Thermometer”
- vprl.ru — “Simple Multichannel Thermometer”
- kit-e.ru — “Dallas Semicoductor Digital Temperature Sensors”
