Arduino COM

Temperature graphs

Fish tanks, terraria, plants, mini breweries, etc often need their temperature and humidity info displayed on a PC. In the past, USB sensors were used for this purpose, such as the Temper (shown below):

Temper

The problem with USB sensors is that their comm protocols are hard to get and the manufacturers are unresponsive. Each new model requires reverse engineering. A better solution is to use an Arduino, which has many sensors and code examples ("sketches"). Unlike USB sensors, which have to be read one-by-one, this plugin can get data from several sensors attached to an Arduino, all in one go (the included Arduino sketch needs to be modified for more sensors).

Instructions

This plugin retrieves data from an Arduino via a serial port. The data is formatted using short tags. For example, "t0" could mean temp. sensor 0, "h0" humidity sensor 0 etc. The retrieved values can be shown in Rainmeter using various meters. An example of a measure reading the data tag "t0":

[msTemp0]
Measure=Plugin
Plugin=Arduino
COM port=3
Baudrate=57600
UpdateRate=#ArduinoDivider#
DataID=t0
Correction=-1.2
Conversion=C2F
MinValue=70
MaxValue=90

Read the comments in the sample skin for more info about the plugin's settings.

Sketch

The skin folder includes a sample Arduino sketch for the DHT11 sensor.

void setup() {
  pinMode(DHTPIN,INPUT);
  lastRead=0;
  dht.begin();
  Serial.begin(57600);  
}

Sensors

The cheapest and the least accurate sensor is the DHT11. More accurate sensors include: BME680, GY21 & HTU12.


DHT-11	GY-21	BME-680	SH12

SparkFun Si7021 | GY-21 HTU21 Sensor | Adafruit BM680

Wiring

Wiring tutorial

A sample wiring tutorial for the DTH11. You only need the simplest 3-wire connection and you don't need an LCD display.

Calibration

If you need to calibrate several temp/humidity sensors, you may want to invest in an expensive, but very accurate reference device.

Hygrometer

Download

Note: the official Rainmeter build has a bug in the meter implementation, corrected in this modded version. The sample skin uses this correction, so use that mod if you want to see the sample skin as intended. Otherwise, you'll need to modify the sample skin to work with the official build.