CheckRainPi -- a rainwater gauge data collection script

This is an easy script for collecting results off the serial port and sending them out to Amazon SimpleDB.

How it works

The script sends the memory dump command to a rainwater gauge attached to the serial port.

It collects the results and stores them in a file.

It then posts just the latest results to a database in the Amazon cloud.

The results can be retrieved at any time by accessing the Amazon SimpleDB.

This script is ideal for running on a Raspberry Pi.

Installation

First get python3 and git.

sudo apt-get install python python-virtualenv git

The following commands will create a python virtualenv and install the script into it.

git clone https://github.com/rvl/checkrainpi.git
cd checkrainpi
./install.sh

Configuration

Find the file raingauge.conf and edit it to your tastes.

In particular, you will need to go to http://aws.amazon.com/ and sign up for a free account, so you can enter your access key into the config file.

Invocation

./venv/bin/checkrain -v --conf=raingauge.conf

Getting results

This will print out all the samples collected so far.

./venv/bin/getrain --conf=raingauge.conf

Running automatically

Put the following in a file /etc/cron.d/checkrainpi.

It will run the script every day at 4PM.

SHELL=/bin/sh
PATH=/bin:/usr/bin

0 16 * * *  pi /home/pi/checkrainpi/venv/bin/checkrain --conf=/home/pi/checkrainpi/raingauge.conf

Complete setup starting from clean Raspbian image

Do the following steps as the pi user. Don't use sudo unless it says.

Initial raspberry pi setup

Do the following steps with this command.

sudo raspi-config

1. Change password to a good long secret password
2. Change language to en-AU.UTF-8
3. Change timezone to Australia/Perth
4. Change keyboard layout to 104 key English (US)
5. Enable the SSH server

Install vim editor because nano sucks.

apt-get update && apt-get install vim

Mobile Internet connection (Telstra)

Telstra 4G dongle config is quite easy. The attached dongle appears as a normal ethernet interface, using the cdc_ether driver.

First check for USB device. The attached dongle will appear as one of the following two vendor strings.

lsusb
Bus 001 Device 007: ID 19d2:1405 ZTE WCDMA Technologies MSM
Bus 001 Device 005: ID 12d1:14db Huawei Technologies Co., Ltd.

The ZTE is well supported by Raspbian and appears as the usb0 interface. The Huawei is supported by newer versions of Linux than Raspbian, so needs an updated config file. When it works, it comes up as eth1 (eth0 is the Raspberry Pi's ethernet port).

Get the updated file:

wget https://sources.debian.net/data/main/u/usb-modeswitch-data/20150115-1/40-usb_modeswitch.rules
sudo chown root:root 40-usb_modeswitch.rules
sudo mv 40-usb_modeswitch.rules /lib/udev/rules.d/40-usb_modeswitch.rules
sudo service udev reload

Edit the Debian networking file.

sudo vim /etc/network/interfaces

Add the following lines:

allow-hotplug usb0
auto usb0
iface usb0 inet dhcp

allow-hotplug eth1
auto eth1
iface eth1 inet dhcp

Bring up connection (choose interface based on attached dongle).

sudo ifup usb0
sudo ifup eth1

SSH Reverse Proxy

For this, we use the autossh software.

sudo apt-get install autossh

Running as the pi user, create a passwordless ssh keypair.

 ssh-keygen

Now, you will need a gateway host somewhere on the Internet that you have access SSH to. It is also nice to have the setting GatewayPorts yes in /etc/ssh/sshd_config, but not required.

On the gateway host, append the created file /home/pi/.ssh/id_rsa.pub to its authorized_keys file.

Add the following to /etc/rc.local (before exit 0 line). Replace myuser@mygateway.host with the correct username and hostname.

autossh -N -f -o "PubkeyAuthentication=yes" -o "PasswordAuthentication=no" -o "TCPKeepAlive=yes" -o "ServerAliveInterval=90" -i /home/pi/.ssh/id_rsa -R "*:6666:localhost:22" myuser@mygateway.host &

Test the SSH connection and accept the host key:

sudo ssh myuser@mygateway.host

Then run it the init script.

chmod +x /etc/rc.local
/etc/rc.local

Check the reverse proxy by trying to login to the raspberry pi from another machine.

ssh -p 6666 -l pi mygateway.host

The above assumes that the gateway has GatewayPorts yes. If not, then you need to login with two hops.

ssh myuser@mygateway.host
ssh -p 6666 -l pi localhost

Create your own gateway host

If you don't have access to a gateway host, one can be created under the Amazon EC2 12 month free usage tier. You would then need to use an dynamic DNS client to maintain a constant hostname. Amazon have instructions in their EC2 documentation.

USB Serial setup

The device will be /dev/ttyUSB0. Just check that the user has permission to open it.

sudo adduser pi dialout

Raingauge setup

sudo mkdir /data
sudo chown pi:pi /data

sudo apt-get install python python-virtualenv git

cd
git clone https://github.com/rvl/checkrainpi.git
cd checkrainpi
./install.sh

cp raingauge.conf site.conf

Edit site.conf according to your settings.

Automatic running with cron

This will run the script every day at 7AM. It will also auto-update the checkrainpi script every week. Run the crontab editor for the pi user:

crontab -e

Put the following lines down the bottom:

 0 7 * * * /home/pi/checkrainpi/venv/bin/checkrain --conf=/home/pi/checkrainpi/site.conf
 0 6 * * * cd /home/pi/checkrainpi && git pull -q
 */5 * * * * /home/pi/checkrainpi/scripts/connect4g.sh
 0 5 * * * /home/pi/checkrainpi/scripts/reboot-huawei.sh