If you want to add ethernet networking to your Arduino based project following are the conventional solutions:

• Buy an Arduino Ethernet that has ethernet already included on the board ~48€
• Arduino ethernet shield for ~33 €

One of the problems with these options is that they don’t support DHCP so you have to hardcode your IP address in the firmware. Besides they seem to cost too much – for this kind of money it would be cheaper to get wireless shields.

One alternative that I have come accros is to use self contained ethernet to serial bridges, while these might not be any cheaper from the previously mentioned options, they are more powerful.
These modules are not much larger than the RJ45 socket itself and are extremelly easy to interface to any controller. Support exists for TCP, UDP, DHCP, SNMP, AES encryption and you can actually configure it to send e-mail when IO pin is triggered so for some extremelly simple applications you might be able to avoid the controller alltogether. What I’m talking about is the XPort from Lantronix.

I happen to have one laying around since we used this in one of the projects many years ago. Nowadays I think you should be able to get one for ~30€ if you search long enough. There’s also a newer generation available called XPort PRO that has full linux running inside of it which allows you to do far more but costs far too much for me (~60€).

There’s also a cheaper and very powerful alternative from Digi called Digi Connect ME 9210 with full Linux running inside it (39€). It has more pins and you should be able to do things like bridging 1-wire sensor network to ethernet without any external controller. I have no experiences with that device though and haven’t found any useful discussions about it so far.

So anyway to get the XPort up and running you first have to give it an IP address. There are basically 2 ways of doing this – either with DHCP (the easy method) or over serial.

Since I wanted to learn a bit about using my Bus Pirate I used it to communicate with the serial port and verify that I can actually enter the serial setup if I wanted to.

Here’s how I connected the XPort and Bus Pirate:

Here’s how it looks like:

To enter the serial setup you would have to do something like this:

$ picocom -b 115200 -p n -d 8 /dev/ttyUSB0
picocom v1.4
 
port is        : /dev/ttyUSB0
flowcontrol    : none
baudrate is    : 115200
parity is      : none
databits are   : 8
escape is      : C-a
noinit is      : no
noreset is     : no
nolock is      : no
send_cmd is    : ascii_xfr -s -v -l10
receive_cmd is : rz -vv
 
Terminal ready
 
HiZ>b
Set serial port speed: (bps)
 1. 300
 2. 1200
 3. 2400
 4. 4800
 5. 9600
 6. 19200
 7. 38400
 8. 57600
 9. 115200
10. BRG raw value
 
(9)>5
Adjust your terminal
Space to continue
 
Thanks for using picocom
 
$ picocom -b 9600 -p n -d 8 /dev/ttyUSB0
picocom v1.4
 
port is        : /dev/ttyUSB0
flowcontrol    : none
baudrate is    : 9600
parity is      : none
databits are   : 8
escape is      : C-a
noinit is      : no
noreset is     : no
nolock is      : no
send_cmd is    : ascii_xfr -s -v -l10
receive_cmd is : rz -vv
 
Terminal ready
HiZ>m
1. HiZ
2. 1-WIRE
3. UART
4. I2C
5. SPI
6. 2WIRE
7. 3WIRE
8. LCD
9. DIO
x. exit(without change)
 
(1)>3
Set serial port speed: (bps)
 1. 300
 2. 1200
 3. 2400
 4. 4800
 5. 9600
 6. 19200
 7. 38400
 8. 57600
 9. 115200
10. BRG raw value
 
(1)>5
Data bits and parity:
 1. 8, NONE *default
 2. 8, EVEN
 3. 8, ODD
 4. 9, NONE
(1)>
Stop bits:
 1. 1 *default
 2. 2
(1)>
Receive polarity:
 1. Idle 1 *default
 2. Idle 0
(1)>
Select output type:
 1. Open drain (H=Hi-Z, L=GND)
 2. Normal (H=3.3V, L=GND)
 
(1)>2
Ready
UART>W%:1000 0x78:100 %:100 0x0D 0x0A (2)
Power supplies ON
DELAY 1000ms
WRITE: 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78 0x78
DELAY 100ms
WRITE: 0x0D
WRITE: 0x0A
Raw UART input
Any key to exit
 
*** basic parameters
Hardware: Ethernet TPI
IP addr - 0.0.0.0/DHCP/BOOTP/AutoIP, no gateway set
DHCP device name : not set
 
*** Security
SNMP is              enabled
SNMP Community Name: public
Telnet Setup is      enabled
TFTP Download is     enabled
Port 77FEh is        enabled
Web Server is        enabled
Web Setup is         enabled
ECHO is              disabled
Encryption is        disabled
Enhanced Password is disabled
Port 77F0h is        enabled
 
*** Channel 1
Baudrate 9600, I/F Mode 4C, Flow 00
Port 10001
Connect Mode : C0
Send '+++' in Modem Mode enabled
Auto increment source port disabled
Remote IP Adr: --- none ---, Port 00000
Disconn Mode : 00
Flush   Mode : 00
 
*** Expert
TCP Keepalive    : 45s
ARP cache timeout: 600s
High CPU performance: disabled
Monitor Mode @ bootup : enabled
HTTP Port Number : 80
SMTP Port Number : 25
MTU Size: 1400
Alternate MAC: disabled
Ethernet connection type: auto-negotiate
 
*** E-mail
Mail server: 0.0.0.0
Unit       :
Domain     :
Recipient 1:
Recipient 2: 
 
- Trigger 1
Serial trigger input: disabled
  Channel: 1
  Match: 00,00
Trigger input1: X
Trigger input2: X
Trigger input3: X
Message :
Priority: L
Min. notification interval: 1 s
Re-notification interval  : 0 s
 
- Trigger 2
Serial trigger input: disabled
  Channel: 1
  Match: 00,00
Trigger input1: X
Trigger input2: X
Trigger input3: X
Message :
Priority: L
Min. notification interval: 1 s
Re-notification interval  : 0 s
 
- Trigger 3
Serial trigger input: disabled
  Channel: 1
  Match: 00,00
Trigger input1: X
Trigger input2: X
Trigger input3: X
Message :
Priority: L
Min. notification interval: 1 s
Re-notification interval  : 0 s
 
Change Setup:
  0 Server
  1 Channel 1
  3 E-mail
  5 Expert
  6 Security
  7 Defaults
  8 Exit without save
  9 Save and exit            Your choice ?

At this point you could go on configuring the device over the serial connection but it’s a bit incovenient so I just gave it an IP with DHCP and used the web interface for configuring.

So with this configuration the XPort will connect to TCP port 12345 on 192.168.1.1 right after restart and we can use this channel to talk over serial port.
To test it let’s bind netcat on the 192.168.1.1:

$ nc -l 12345

And from the bus pirate shell we have to exit the monitor mode, reset the device and enter the serial bridge mode:

UART>w
Power supplies OFF
UART>W
Power supplies ON
UART>(1)
UART bridge
Reset to exit
Are you sure? y
 
test

You should now see test on the netcat shell and anything that wou write into the netcat session should show up on the buspirate shell.

I’m slowly expanding my home automation systems and the latest addition to that is this weather station.

The large rectangular thing in the lowest position on the antenna pole is a WIFI panel antenna.

I decided to add the weather station primarily in order to measure wind speeds so that my scripts would be able to make better decisions about closing and opening the greenhouse windows. I’m not so much worried about keeping optimal temperature in there but rather about making sure that the windows won’t get ripped off on a windy day. Another good reason is that I just like to have a lot of data and nice graphs 🙂

I wanted a relatively cheap and open weather station that I could integrate into my setup without too much effort. The closest match seemed to be this one that is sold by Sparkfun. It has an anemometer, wind vane and rain gauge. Interfacing it with a microcontroller is very simple since the wind speed and rain gauge are just Reed switches and the wind vane changes resistance. The only external component that you need is a 10k ohm resistor for the wind vane and of course some kind of microcontroller to take the measurements.

I ordered mine for 60€ from Watterott electronics which is a German shop that sells a lot of Sparkfun stuff among other things.

I hooked it up to an Arduino Uno using a small library that I wrote and connected that in turn over a USB cable to a beagleboard that serves as a controller for my home automation stuff.

The small red board on this picture is a BMP085 barometric pressure sensor.

In general the weather station seems to work well enough. I’m not entirelly sure about the correctness of the measurements from the rain gauge since I see some rain measurements even though it has been constantly below -20 degs celcius here which obviously rules out rain. Here’s what the rain gauge looks like:

Inside you will find a seesaw with 2 buckets with a magnet in the pivot that triggers contact in the Reed switch every time the equilibrium position is changed.

While the design of the rain gauge is beautiful in its simplicity it doesn’t seem to be very precise. For example sometimes the other end will bounce right back after emptying and I have no theory yet about the reason behind the random small measurements that I currently get from it.

Anyway, here’s some real time wind information from my weather station through open.sen.se and pachube: