14
votes
Accepted
The use of 4.7kOhm resistor with DS18B20 temperature sensor
The product page FAQ [https://www.maximintegrated.com/en/support/faqs/ds18b20-faq.html] has an entry:
Q: Is the 4.7kΩ resistor needed for 5V and 3.3V operation?
A: Yes, the 4.7kΩ pullup resistor is ...
- 6,954
7
votes
Accepted
Frequent ON OFF in SSR
You need to implement hysteresis. Set two temperature points around set_temp. One a little higher to be a limit for turning the heater off and a one a little lower then set_temp to turn the heater on.
...
- 17.2k
6
votes
The use of 4.7kOhm resistor with DS18B20 temperature sensor
Adding to jose's answer above to answer your other two questions
And why this resistance?
When the device doesnt have its own power supply it uses the power going through the pull up resistor-thus ...
- 395
6
votes
How to measure the supply voltage of Arduino without using an analog pin
Yes, you can do it.
You can measure the voltage of the internal (approximately) 1.1V reference voltage using the ADC and use the results of that to calculate what the reference voltage you used (VCC) ...
- 104k
6
votes
How to perform multitask using arduino such as update data as well as check condition?
You need to think about this with a real-world analogue.
I like to use boiling an egg...
There are three ways you can boil an egg:
Blocking operation
Put the egg in the boiling water
Stand there ...
- 104k
5
votes
Accepted
ESP8266 cannot read DHT22
I found, that the pin mapping printed at the board of the nodeMCU does NOT match the pin mapping in the library/software.
Check out this issue/solution. It states the correct pin mapping (e.g. pin 2 ...
- 51
5
votes
Accepted
Thermometer project shows fluctuation due to varying sensor value and voltage
What you need to do is take an averaged reading, this is because the sensor is always fluctuating, noise on the 5V line or the signal line. There are possible hardware solutions.
Adding a capacitor ...
- 1,437
5
votes
Arduino freezing with OLED display
Because your program uses various String objects in several different sizes, there's a good chance that heap memory (in RAM) is getting fragmented to the point that String allocation begins to fail, ...
- 8,800
5
votes
Problems with I2C connection on ESP8266 - 12F, which pins should I use?
Unlike most Arduinos, the ESP8266 doesn't have a hardware TWI, so I²C is bit-banged in software. This means that you can use any GPIO pins. By default, Wire.begin() initializes pins 4 (SDA) and 5 (SCL)...
- 1,300
5
votes
Accepted
Is there a way to shift through sensors
As I mentioned in the comments, one way to do this is to use a multiplexer.
You haven't said which temperature sensors you are planning to use, so I'll illustrate this example using the TMP36 ...
- 1,032
4
votes
LM35 at higher temperatures
No, you cannot. The LM35 is rated for an absolute maximum junction temperature of 150°C. Any higher than that and you will damage it.
For temperatures above that you are better using a thermocouple....
- 104k
4
votes
Accepted
Remote temperature and humidity sensor with long battery life
I made a Temperature and humidity sensor - battery powered in 2013. It is powered from 3 x AA batteries, and lasted, as I recall, until a couple of months ago before I changed the batteries. That is, ...
- 36.4k
4
votes
Plug/socket between thermocouple wires and the amplifier
I do not know the accuracy that you will require in your temperature measurements.
Your idea of using copper wire and connector sockets is reasonably ok as long as you are aware of the following : ...
- 600
4
votes
What could I use to vary the temperature of a Heating Pad?
In principle, I don't see any problems. Your heating pad uses 12V and 10W, which means it would be consuming slightly less than one amp of current. The MOSFET you linked can go up to 5A (needing a ...
- 36.4k
4
votes
What difference makes resistance of thermistors?
Skip to the end to get the easy answer!
Your choice of thermistor and bias resistor values depends on the following:
1. How much current do you want to spend?
2. How do you want the thermistor ...
- 407
4
votes
Is there a way to shift through sensors
Have you looked at OneWire temperature sensors? You connect them to a bus IC and the bus IC to your Mcu. This allows you to multiplex many sensors.
You can also forego the master bus IC and just ...
- 332
4
votes
Accepted
DHT11 Sensor Code Fatal Error
The examples I can see from Adafruit say
#include "DHT.h"
or
#include <DHT.h>
But you wrote
#include <dht.h>
They aren't the same.
Further, the examples for the Adafruit library ...
- 6,954
4
votes
Accepted
Wemos: relay shield doesn't work on top of the stack
Yes, there is a pin conflict. The relay uses D1, however D1 is (as you can see from looking at the schematics) part of the I2C connection for the SHT30.
You will have to find some way of modifying ...
- 104k
4
votes
Accepted
Can I generate 5 sec delay within an interrupt program?
You don't need interrupts for any of that. Your main loop just needs to test the switch, eg.
void loop ()
{
if (digitalRead (button) == HIGH) // assuming LOW means pressed
return;
// ...
- 36.4k
4
votes
Accepted
DHT11 Sensor : Stand-by or Shut down?
At times like this it is useful to refer to the datasheet. You can, in that document, find this paragraph:
4. Power and Pin
DHT11’s power supply is 3-5.5V DC. When power is supplied to the ...
- 104k
3
votes
Accepted
How can BMP180 measure a temperature too?
If you read the data sheet (on the site you point to) you see plenty of references to temperature:
The BMP180 is designed to be connected directly to a microcontroller of a mobile device via the I ...
- 104k
3
votes
Accepted
Reducing read time for reading DS18B20 temp sensors
After nearly a year and a number of experiments later, I've learned a little bit more about using these devices:
Issuing the sensors a Skip ROM command followed by Convert T command starts all ...
- 14.9k
3
votes
Failed to read DHT22 sensor using Arduino Uno
I suggest you to modify the following lines of code to check which reading has issue.
if (isnan(h) || isnan(t) || isnan(f)) {
Serial.println("Failed to read from DHT sensor!");
return;
}
- 69
3
votes
Why do my temperature sensor values become inconsistent when additional hardware is added to the board?
Don't take power for LCD from Uno pins. Connect LCD power to separate power source.
- 105
3
votes
What difference makes resistance of thermistors?
The standard way to measure a resistive sensor is to make a voltage
divider with the sensor and a fixed resistance between Vcc and GND, like
this:
Vcc
│
Rb
│
├─── analog input
│
Rx
│
GND
...
- 40.2k
3
votes
Accepted
Help using thermistor with esp8266
Considerations about the ESP8266 analog pin
The ESP8266 has only one pin that allows analog read. This pin is call A0 on the NodeMCU module or A on the ESP8266 Huzzah (some other ESP module don't ...
- 146
3
votes
Can I generate 5 sec delay within an interrupt program?
It's bad practice to use a delay within a timer, and 5 seconds is a huge amount of time. Also print statements and possibly lcd print statements I would not advice.
What is better, is to calculate ...
- 12.8k
3
votes
Accepted
Thermistor doesn't work
The series resistance is 220 Ohms (Red, Red, Brown).
You also need to take into account the thermistor resistance at 25C. Assuming its 10K. Hence choosing a 10K series resistance will make the ...
Only top scored, non community-wiki answers of a minimum length are eligible