The mLink Home sensor is a compact multiple sensor module featuring a DHT22 temperature/humidity sensor, a LDR light sensor and a PIR motion detector. These features make this module ideal for sensing occupancy and environmental conditions within a room.

Communication with the sensors is made via the modules serial (I2C) interface which is compatible with microcontrollers featuring an I2C interface including most types of Arduinos. Being an mLink module it is also compatible with other modules in our mLink range and can simply be daisy-chained together allowing multiple different mLink modules to be controlled via one serial interface.

For Arduino users you can use the mLink library (see below for library and examples) to control any type of mLink module. Only one single instance of the library is needed to control multiple types of mLink modules resulting in very little resource overhead and therefore making it great for Arduinos with small amounts of memory and pin counts.

Module code:

HCMODU0198

Supply Voltage(VDD):

5V (3.3V with solder pad bridged - see forum post)

Current consumption:

7mA

Current consumption (sleep):

0.5mA

I2C Interface speed:

400kbits/s (fast mode)

I2C default address (HEX):

0h5B

Maximum number of modules:

5 with pullups fitted, 112 with pullups removed*

Temperature sensor range:

-40 to 80oC

Temperature sensor resolution:

0.1oC

Humidity sensor range:

0 to 10 %RH

Humidity sensor resolution:

0.1 %RH

LDR sensor range:

0 to 255

PIR Trigger on time:

~4 seconds

PIR Sensor angle:

100 degree cone

Sensor range:

~3 to 5 metres

Module dimensions ex headers (LxWxH):

45mm x 30mm x  18mm

*Note the maximum number of connected modules will depend on cable lengths and power requirements of each module. Do not exceed 5 mLink modules connected in series with I2C pullups fitted to all modules. For disconnecting pullups see forum post.

Arduino Connection Example:

Because the modules use an I2C interface this also means multiple modules can be controlled from a single Arduino I2C interface simply by daisy-chaining them together. Note to control multiple mLink modules of the same type requires changing the default I2C address of the additional modules. See example Arduino sketch on forum post.

Example Arduino Sketch:

1. #include "mLink.h"                              // Include the library
2.  
3. #define I2C_ADD 0x5B                            // Default I2C address
4.  
5. mLink mLink;                                    // Create an instance of the library
6.  
7.  
8. void setup()
9. {
10.   Serial.begin(9600);
11.   mLink.init();                                 // Initialise the library
12. }
13.  
14.  
15. void loop()
16. {
17.   mLink.HSense_Start_Meas(I2C_ADD);             // Trigger a new temp/hum measurement
18.   while(mLink.busy(I2C_ADD));                   // Wait for the measurement to complete
19.  
20.   // Read the sensors
21.   float temp = mLink.HSens_Temp(I2C_ADD);
22.   float hum = mLink.HSens_Hum(I2C_ADD);
23.   byte LDR = mLink.HSens_LDR(I2C_ADD);
24.   boolean PIR = mLink.HSens_PIR(I2C_ADD);
25.  
26.   // Print out the results
27.   Serial.print("Temperature: "); Serial.println(temp, 1);
28.   Serial.print("Humidity: "); Serial.println(hum, 1);
29.   Serial.print("Light: "); Serial.println(LDR);
30.   Serial.print("PIR: ");
31.   PIR ? Serial.println("Triggered!") : Serial.println("Idle");
32.  
33.   Serial.println();
34.  
35.   delay(1000);
36. }

For more information, including exclusive Arduino library, sketches, spec and register map, please see our support forum here.