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24 votes
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Is soil moisture sensor corrosion normal?

If you think about what is happening you have a very hostile environment for electronics (moisture - sometimes large amounts, soil PH and electrical current induced electrolysis) The Hookup Guide for ...
Steve Robillard's user avatar
23 votes

Is soil moisture sensor corrosion normal?

Yes, this is normal for a DC drive configuration. You're effectively setting up an electrolysis experiment where the copper atoms on the positive electrode are being ionised, transported via the soil'...
stefandz's user avatar
  • 330
9 votes

Using 5 volts on an mcp3008

First, lets check the characteristics of the MCP3008 again: Single supply operation: V_dd = 2.7V to 5.5V All Inputs and Outputs < V_dd + 0.6V (this should include V_ref) 200 ksps max. sampling ...
Ghanima's user avatar
  • 15.9k
9 votes

Looking for a starter kit for my 10 year old

There are a few things in addition to the pi itself that are required, and if you do not already have them, you would want a kit that includes them. Generally these are appropriately priced, but ...
goldilocks's user avatar
  • 59.1k
9 votes

ESP 8266 and Raspberry Pi communication without an Internet connection

You could have the Raspberry Pi behave like a WiFi access point (using hostapd and dnsmasq, introductory documentation from the Foundation is here) with a static IP and then have the ESP8266 join the ...
Roger Jones's user avatar
  • 1,484
8 votes

Do I have to connect a resistor to my DHT22 humidity sensor?

It seems necessary for reliable readings. I started my project without pull up resistor and the humidity measurement started dropping down. It may start correctly but deterioate later. Since I was ...
Benny's user avatar
  • 181
8 votes

How to Connect 6 ultrasonic sensors to a raspberry pi?

The following code will scale to multiple sensors. If you want all triggers to be at exactly the same time then connect the same GPIO to each of the triggers. Use that GPIO for the last sonar's ...
joan's user avatar
  • 71.1k
8 votes

Is soil moisture sensor corrosion normal?

Yes, it's normal. One electrode (the anode) will oxidise. That said, it shouldn't happen so quickly. I guess you have the sensor powered constantly. That means you always enable corrosion. What you ...
Bex's user avatar
  • 2,929
6 votes
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Connecting DS18B20 temperature sensor with RJ45 connector?

Connecting the DS18B20 to the Ethernet port would either not work or the effort to make it work (even if it was possible) would be excessive for someone starting out with a Raspberry Pi. As you state,...
d3noob's user avatar
  • 1,876
6 votes
Accepted

nutrient sensors for hydrophonics with raspberry

You need a TDS (Total Dissolved Solids) meter (aka EC/PPM meter) for measuring the nutrient content in your water, and you should also have a pH meter for maintaining a proper alkaline/acid level. I ...
stevieb's user avatar
  • 1,456
6 votes
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Scaling of digital reading of pressure sensor

Linear for the win! y = (slope * x) + intercept is the classic linear formula, in your case, x=sensor, y=bars, so the formula becomes bars = (slope * sensor) + intercept ... and you have two data ...
Beege's user avatar
  • 176
6 votes

Is joining NEO6MV2 module and RC 522 module together to Raspberry Pi possible?

Short answer YES. The GPS module uses Serial = Yes you can do that with a Raspberry Pi https://www.raspberrypi.org/documentation/configuration/uart.md The RFID module uses SPI = Yes you can do that ...
Mats Karlsson's user avatar
6 votes
Accepted

How to connect multiple sensors to an rpi with the I2C?

I2C is a bus system and allows you to connect multiple sensors to the same pins. The master system (the Pi) lets the sensors know who should respond by placing that sensor's address on the bus. In ...
joan's user avatar
  • 71.1k
5 votes

Sensor to detect water/liquid level

I found this Raspberry Pi water level meter - should answer the question is there water or not , but also a level indicator , like a measuring cup. 12" eTape Liquid Level Sensor https://www.adafruit....
sbayercisco's user avatar
5 votes
Accepted

I want to use a common power supply to pi and sensors BME280 and BMA180 (sensor modules). Is it possible?

BME280 Adafruit I2C or SPI Temperature Humidity Pressure Sensor First, I assume that this sensor module is referred to, not the bare sensor itself. There it reads: So we made it easy for you to ...
Ghanima's user avatar
  • 15.9k
5 votes

Do I have to connect a resistor to my DHT22 humidity sensor?

I use a 10K pull-up from pin 2 (DATA) to pin 1 (VCC), and always use 3V3 to pin 1. On 5V the sensor heats up a few degrees celsius. Also, pay attention to nearby heatsources (laptop, your breath, ...
user400344's user avatar
5 votes

Getting a CO2 sensor for Arduino to talk to Pi

To read this sensor on the Pi, you can use one of two methods. First of all, you could have Arduino read the sensor and send the readings back to the Raspberry Pi, over a connection, either I2C, ...
recantha's user avatar
  • 4,479
5 votes

How to approximate room temperature in a better way

That's the main problem with the Enviro pHAT, and the SenseHAT for that matter - proximity to the Pi affecting results. You're better off getting a Dallas 1-wire temperature sensor, preferably one ...
recantha's user avatar
  • 4,479
5 votes

Connecting 18B20 temperature sensor to Raspberry Pi 3

I've written a blog post detailing how to connect DS18b20 temperature sensors to a Pi here, but the short version is this: The sensor has 3 pins: Sense 3.3V Ground Which is which should be indicated ...
Lawrence's user avatar
  • 2,672
5 votes

Weather proofing a Pi

You've probably searched for a cover (as I just did), and didn't find anything that you could buy. That being the case, you must shift into "DIY Mode", and come up with your own solution. Before going ...
Seamus's user avatar
  • 22.2k
5 votes

Powering a sensor using an external power supply board

Yes, (in general) in this case you should wire the ground terminal of all devices in your circuit together. This provides the necessary common ground reference voltage for them to interoperate. Your ...
Seamus's user avatar
  • 22.2k
5 votes
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Pi locking up trying to use rising/falling edge detection

Solution: Add: dtoverlay=gpio-no-irq to /boot/config.txt. Previously the kernel would automatically disable interrupts when you set one of rising/falling edge detection methods but that apparently ...
Nick's user avatar
  • 195
5 votes
Accepted

5v/12v power source/submersible water pump/RPI/relay. What kind of combination is suitable?

12V pump will require 12V PSU. 20LPM is a pretty reasonable flow rate for a small pump so your pump PSU will need to have enough power to drive the pump - check the max current draw on startup (which ...
Bruce Heath's user avatar
4 votes
Accepted

Why are one wire temperature sensor readings so slow?

From the datasheet currently hosted by Adafruit: Converts Temperature to 12-Bit Digital Word in 750ms (Max) From s445203's answer here: ...as far as I can tell from the w1_therm source code ...
goobering's user avatar
  • 10.7k
4 votes

How to send temperature and humidity sensor data from a raspberry pi to a pc wirelessly?

From the help of user goobering, based on mattrichardson.com and Flask RESTful documentation. I have solved the problem. Here is my solution for anyone who face the same problem. First write a python ...
Komgcn's user avatar
  • 171
4 votes
Accepted

How does RPi "know" when it hasn't got enough power

The Pi (at least all since B+) has a power monitor - the APX803 chip triggers if voltage falls below 4.63±0.07V. This drives the power LED and is connected to a pin on the chip. In fact the Pi will ...
Milliways's user avatar
  • 60.3k
4 votes

Sensor Bus for USB

RS-485 is another bus likely to be suitable for this task (though maybe a little technical overkill). It is based on a differential signaling on a single twisted wire which makes it quite robust and ...
Ghanima's user avatar
  • 15.9k
4 votes
Accepted

DHT11 or GPIO Library to Use in C

For the GPIO libraries available on the Pi see http://elinux.org/RPi_GPIO_Code_Samples For C the usual choices are wiringPi bcm2835 pigpio (github)
joan's user avatar
  • 71.1k
4 votes
Accepted

Smoke sensor MQ-135

The analog pin will give a level reading depending on 'how much' smoke is surrounding the sensor. Analog cannot be read directly by the Raspberry Pi so, yes, to get that kind of reading, you will need ...
recantha's user avatar
  • 4,479
4 votes
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Air Compressor or pump for raspi?

I would get a cheap tire inflator (one that lets you set the pressure) that runs from a cigarette lighter. Then I would cut the plug off the power cable, attach it to a 12V relay, and control the ...
Steve Robillard's user avatar

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