Monitors a network connection and reset a switch (or any other device) if that fails.

I created this sketch because some cheap switches in our office tend to fail after some days of operation and need to be reset manually.

The sketch was tested on an Arduino Meda 2560, an ethernet shield, a relay connected to PIN 12 and a HC-05 bluetooth PBC connected to the default serial port. After the connection timed out several times, the relay will disconnect the power line to the switches for 2 seconds.

To test the connection, the uC can send a ping command to a remote IP and awaits the repsonse in a timely fashion or it can do DHCP requests on a regular basis and check if these succeed.

When configured to synchronize its time with a NTP time server, office hours can be defined during which resets of the controller switch should be suppresed.

The sketch will accept administrator commands on the serial port (thus on bluetooth) to modify the target IP, the timeout and the retry count and store them opermanantly in EEProm:

J=mac  set the mac address of the control (aa:bb:cc:dd:ee:ff)
I=ip   set the IP address to ping to check if the network works (111.222.33.44)
N=ip   set the IP address of the time server to query
F=1|0  fetch time from time server (1) or do not (0)
T=4    timeout for ping and dhcp requests (seconds) [1,...,180]
W=10   wait time between checks (seconds)           [1,...,180]
Z=2    timezone difference in hours (2=CEST)        [-14,...,14]
R=10   set number of retries before a network outage is assumed [1,...,100]
P=1|0  pause on|off
M=1|2  set monitor mode: 1=ping requests, 2=dhcp requests
S=9    set office start hour [0,...,24]
E=19   set office end        [0,...,24]
Y=17   same for fridays      [0,...,24]
    @      toggle reset @ midnight
C      show config
U      update time from timeserver now
B=4711 reboot the micro controller ("4711" is fixed and acts as a confirmation)
X=4711 factory reset the micro controller
Q=4711 reset the attached switch now
H      help