I wanted a multi usage node for my house. The goals are simple:

• I don't want it to be battery powered, but i have to powered it with usb charger,5V or 12v alimentation.
• Every node has to send temperature via 1 to 3 ds18b20 sensors (one node can be used for 2 or 3 pieces in the house)
• I wanted to add a DHT22 for room where humidity can be interesting or critical (bathroom or woodworking shop for exemple)
• Some of them are planed to be used with a PN532 RFID sensor for activate an alarm, open a door or other things like that
• I wanted to use some of them with a BH1750FVI for monitoring the outdoor light, or the lux in a room
• It has to communicate with me, so i wanted a RGB led, and a buzzer, so if i want a blink or a simple buzz or melody, for exemple in a room where i can't hear the doorbell, or beep with the RFID scan, it can do that.

So i have tried to do this as compact as possible, but i also wanted it to be easy to build.

That's why i have keeped an arduino nano instead a pro (it's still very cheap), who's avoid me to add a lots of smd components. To keep it pretty small, i have to use some smd, like resistors and the RGB led.

For security, i have placed a spot for an ATSHA in SOT-23 package, with his smd resistor and capacitor.

I have placed two other digital pin with a fan plug (KF2510 3P), to be used with relay and/or motion detector.

I have placed in the left top of the board some bonus connector, just in case : three analogics pin, one digital PWM pin, and one 5v, one 3.3v and two ground pin.

And finally, for the case it will be used in a Gateway mode, i have placed a push button for insertion (actually useless for me with Domoticz).

In the case of using the board in a Gateway mode, you have to shorten a switch to the GW pin, in other case, shorten it to the DS18 position (activation the activation button will deactivate the ds18b20). In the same way, the three colors of the RGB led can be used instead of three analog/digital pin (R/D4, G/D5, B/A2), so we can choose for exemple just one color of the led, and still use the two other pin for sensors.

The project is still in progress, i actually testing the board.

03/04/16:

The board was tested except for the buzzer and the atsha module (don't have both), and except for the led, all works fine. I still investigate why the led don't want to work

04/04/16

I found a bad datasheet for the original led (look's like there are different RGB5050 in same package...) If i solder the led with a 180° rotation, it works (the green and the blue are reversed, but use the same resistor, so i juste have to adapt the code)

Corrections planned in v1.1:

 -rename RDS1 (resistor for ATSHA) in R1
 -add value for C1 and R1 in pcb
 -add + and - label for all the 3pin fan plug in the PCB (ds18-1, ds18-2, ds18-3, D4, D7 and DHT22)
 -enlarge the three holes 
 -change the order of the LUX pinout (actually 5V-A5-A4-GND, next 5V-GND-A5-A4) to allow plugging the BH1750 sensor directly to the PCB
 -correction for the RGB led on the pcb
 -the D4 pin is used both : for the DHT22 connector, and for the led/D4 fan connector, i will keep the D4 for the DHT22, and use another pin for led/fan connector (probably D3 for the interrupt capacity, and using another pin for the ds18b20)
 -change the location on the pcb for the radio module to allow longest radio module (nrf24l01+pa+lna SMA antenna) to fit on the pcb
 -add a 3.3v regulator (0.5A) and enlarge wire from the ext 5v to the 3.3v radio pin to allow more power for the power amplified nrf24l01+ (add onboard switch to allow powering radio module from the arduino for non amplified radio module)
 -change the buzzer connector (just two simple pin to use every type of buzzer)
 -change the switch association to the button, now linked to D7, and add a pull-down capacitor to the switch
 -put all the soldering switch and smd things under the board and not under the arduino (can be changed if needed after soldering arduino)