I finally went on with the project and received the pcbs last week... my soldering oven is running and I could finish the first board (still some parts are missing :-( ) If only I had more time to work on that...
Here are some impressions:

I soldered some cables so that I can program it and check via ftdi...

More to come soon...

As I read your post again, you mean something like this:
http://de.aliexpress.com/item/5-sets-Double-Row-Female-Socket-SMD-2-10-20pin-1-27mm-Pin-Header-connector/32542921161.html?isOrigTitle=true

@GertSanders: On aliexpress you can find sets of male and female 1.25mm connectors, do you think about something like that:
http://de.aliexpress.com/item/20sets-Micro-1-25mm-5pin-Cable-JST-1-25-5-Pin-Male-Female-Connector-plug-with/32464250609.html?spm=2114.010208.3.2.BMcTZF&ws_ab_test=searchweb201556_9,searchweb201644_5_505_506_503_504_301_10020_502_10001_10002_10017_10010_10005_10006_10011_10003_10021_10004_10022_10009_10008_10018_10019,searchweb201560_2,searchweb1451318400_-1,searchweb1451318411_6448&btsid=8ded8c25-db33-49ed-835b-307cb83c0f47

@tbowmo: Sounds very impressive, chapeau! I'm looking forward to seeing your design when it is finished!

@TD22057: My dealer in China does some panelization for me as well, last time I ordered 20 board (size about 25x45mm) and I received 42... That was more than fine for me. But thanks for the link!

Hi all,
many thanks for all the valuable input!
I will share my files after having tested the board by myself for the first time!

@GertSanders: I've never thought about using the SMD version of NRF24L01, it really looks interesting!

@tbowmo: Your board size is really impressive, are you also using the EEPROM and ATSHA on that small size board?

The smallest and still (hopefully) manufacturable for me seems to be around 44x21mm...

Right now I'm waiting for all of the parts of my reflow oven, I have some boards for testing here and in case I'm successful with reflowing, I will order new boards in China.

Best regards,
Philipp

Hi TD,
many thanks for the library, I incorporated the drill holes and it looks much better now!

Best regards,
Philipp

Hi there,

I had some more time to work on it and I rearranged the parts on the board. One question for me is how big to make the drill holes for mounting? Is 2mm ok?

I will clean up the silk screen writings the weekend and then send it out to China :-)

Many thanks so far,
best regards,
Philipp

Regarding the MYSX connector, I have seen the specification before but for me the 2.54mm pinheads are way to big since I wanted to have a really small board that I can also use for quite small sensors (window open for example). I changed some connections and came up with that scheme now:

I added the caps for the ICs, many thanks again for the hint!
Philipp

So this could be an updates pin assignment:

Arduino Pin/ Function/ Pinhead
0/ RXI/ not used
1/ TXO/ not used
2/ D2/ NRF24 / Pinhead 1 / Button (via jumper)
3/ D3/ Pinhead 1
4/ D4/ Pinhead 2
5/ D5/ Pinhead ISP
6/ D6/ LED
7/ D7/ LED
8/ D8/ 25AA256
9/ D9/ NRF24
10/ D10/ NRF24
11/ MOSI/ Pinhead ISP
12/ MISO/ Pinhead ISP
13/ SCK/ Pinhead ISP
A0/ A0/ Voltage divider
A1/ A1/ Dallas 18B20
A2/ A2/ Pinhead 2
A3/ A3/ Pinhead ISP
A4/ SDA/ Pinhead I2C
A5/ SCL/ Pinhead I2C
A6/ A6/ Pinhead 2
A7/ A7/ Pinhead 1

What do you think?
Best regards,
Philipp

Hey guys,

many thanks so far, I will incorporate TD's ideas tomorrow.
For the A7, many thanks to Gert! Only A0-A5 can be used as digital pins so I will change this!
Design rule check was fine.

Thanks again and have a nice evening,
Philipp

Hi everyone,

after I had my first PCB manufactured last year in China, I'm a little bit addicted to designing and soldering new boards so here's another idea for a universal board. I'm building my own reflow oven right now, so I will try to directly use smt parts without using an arduino pro mini on top of my board.

The scheme looks like this:

I added as many parts as possible and tried to make nearly all other pins for Arduino accessible with some 1.25mm pinheads. Here's a list of all the pins and where you'll find them:

Arduino Pin/ Function/ Pinhead
0/ RXI/ not used
1/ TXO/ not used
2/ D2/ NRF24 / Pinhead 2 / Button (via jumper)
3/ D3/ Pinhead 1
4/ D4/ Pinhead 2
5/ D5/ Pinhead ISP
6/ D6/ ATSHA
7/ D7/ LED
8/ D8/ 25AA256
9/ D9/ NRF24
10/ D10/ NRF24
11/ MOSI/ Pinhead ISP
12/ MISO/ Pinhead ISP
13/ SCK/ Pinhead ISP
A0/ A0/ Voltage divider
A1/ A1/ Pinhead 1
A2/ A2/ Pinhead 2
A3/ A3/ Pinhead ISP
A4/ SDA/ Pinhead I2C
A5/ SCL/ Pinhead I2C
A6/ A6/ Dallas 14B20
A7/ A7/ LED

On the front of the board, there's the Atmega, an ATSHA, an EEPROM and a D18B20. on the back, I have two tactile switches and 3 LEDs, the idea is to drill holes in the box and access them from the bottom side while the additional sensors will be in front of the Atmega chip. Besides the ISP head for programming, I added some more digital lines to the ISP pinhead so the pinhead can also being used to connect to another serial device (with the digital pins being CS lines).
There are two connectors for connection to sensors etc and an I2C connector.

Size of the board would be 44.1x23.5mm.

What do you think of this layout? Is there any wrong connection regarding Arduino pins? Any ideas to improve the layout?

Many thanks for your input in advance,
best regards,
Philipp

Long time no see... I had time to work on my sensors lately and here are some pictures of my humidity sensor which is running here for three months now:

I left out the power regulator shown above and also desoldered the LED and voltage regulator of the Arduino to safe power. The sensor is directly powered by 3.7V of the lithium battery. The voltage is measured and the battery will be recharged when it goes down.
Since I also built a 3D printer lately, I was able to put the sensor into a little box. Now I can easily measure humidity and temperature in my bath room and see it in fhem on a raspberry.

Currently I'm working on my next pcb... I will show the next one when I'm finished in a new thread.

@BulldogLowell I just reinstalled arduino and now it is working... thank you for testing and telling me!

Hi everyone,

I tried to compile the code for the HumiditySensor but it does not work. I downloaded the latest Arduino-master from Github, added all libraries but when I compile the code of the HumiditySensor, I get this answer:

HumiditySensor.cpp.o: In function loop': /Users//Desktop/Desktop/HumiditySensor.ino:38: undefined reference to DHT::getTemperature()'
/Users//Desktop/Desktop/HumiditySensor.ino:51: undefined reference to DHT::getHumidity()' HumiditySensor.cpp.o: In function setup':
/Users//Desktop/Desktop/HumiditySensor.ino:22: undefined reference to `DHT::setup(unsigned char, DHT::DHT_MODEL_t)'

I tried other sensors (for example distance) and they compile and work.
I'm using a Mac, any other things of relevance?

Thanks a lot,
Philipp

@gloob : The scheme shown above is still the same, I only added a capacitor in parallel to the voltage divider!

Hi everyone,

I received the last parts on monday and populated 2 boards so far. I found out, that one header for nrf24 is not working properly... most likely since the wires are too far away from the capacitor. The other header is working perfect. Here are the first pictures of the populated board:

Though the hand soldering of the sot23-6 was not easy at all, I managed to do it. I tested the boards with the BatteryPoweredSensor and the voltage divider is working properly. I will now start to program more and see which sensor I can build with that board.

Thanks again for all your help,
Philipp

There are several cheap producers that you can find at aliexpress.com. Just send them your gerber file and they will send a quote... I paid 16,80$ for ten up to size 5x10cm last time...