This is the first version of my "water level alarm".
It is monitoring the water level in a dam.
If the water level gets to high or to low it sends a alarm SMS with the current water level.
The alarm also respond to SMS that is sent to it.
If the message text contains the right command it will respond with a SMS to the sending phonenumber that include the current water level in cm.
All settings (including HIGH level, LOW level, Alarm ON/OFF, phonenumber to send alarm to, clock, calibration) is configured in the menu.
ATMEGA8 - acts as a serial LCD and serial keypad. Sends keypresses to master MCU. Master MCU controls the LCD by serial commands.
I used an extra ATMEGA8 because they cost <1$ on ebay.
ATMEGA328 - Master MCU. Checks waterlevel every 5 minute and reads/sends SMS.
MCP3201 - 12bit ADC. The internal 10bit ADC that the ATMEGA MCU has was not good enough for my sensor.
DS1307 - The RTC is used because I save 24h history. By pressing a key you can go back in time and see the water level.
Pressure sensor 4-20ma, 0-0,3bar (0-3m) Realy good sensor!
GSM module TC35 - The module is basic (no GPRS) but has a low price. It works good, I wrote some simple functions to read/send SMS.
I used transistors to convert the modules 2.65v signals to 5v.
I think I will make a version 2 that include a SD-card for long term logging of the water level.
Version 2 will use DS1302 RTC instead of DS1307 because it can trickle charge a supercap or battery.
It would also be fun if I could learn to use Eagle and make a more professional PCB.
I do not hava a picture "in action" but the only thing on the LCD is time & date and the current water level in cm.
Here is two pictures of the project.