Multichannel Temperature logger [120637]

I present here a six channel temperature data logger. The unit uses the DS18B20 digital temperature sensors. It also has a Real Time Clock (RTC-DS1307). The RTC supplies the time stamp for the logged data. A 4x4 numeric is used for setting the time/date and the logging interval. The keypad is also used to start/stop the logging. I also use a 4x20 LCD to display the current time/date instantaneous temperature from one of the sensors. An SD/MMC is used for saving the logged data. Due to the temperature resolution of the sensors +-0.5oC and the min. logging time of 1sec. this logger is most suitable for environmental monitoring. The unit was build around the Microchip PIC18F420 microcontroller and the code was written using PIC MIKROC from MikroelektroniKa. For test I used the easypic6 development board from Mikroelektronika, their RTC2, and the MMC/SD board. http://www.mikroe.com/eng/products/view/138/mmc-sd-board/ http://www.mikroe.com/eng/products/view/197/rtc2-board/ http://www.mikroe.com/eng/products/view/297/easypic6-development-system/ The code, schematics and latter a pcb design is included.

Power Unit

Currently the unit uses an external DC power source and the 7805 regulator to supply current to the unit. I think for the unit to be more useful it is better to re-design the unit to use AA batteries. I think the best is to use DC-DC step up convertor IC. I will be very nice to have ideas about such addition to the logger circuit.

PCB:

I am now having a PCB layout for the project. I hope that I will soon get the PCB's made and then fully test the layout.

Project Elements

schematic.jpg (JPG, 965.61 KB)

top-layout.jpg (JPG, 306.1 KB)

bottom-layout.jpg (JPG, 310.27 KB)

top.jpg (JPG, 148.54 KB)

bottom.jpg (JPG, 529.97 KB)

code.zip (ZIP)

120367_TempLog.X.zip (ZIP)

C18 Software version

CSV_and_Key.zip (ZIP)

CSV file for the SD card and a document describing the keypad functions

Discussion (4 comments)

jean pierre gauthier 8 years ago

Hello I am interested in your system to measure the temperatures at various levels in my little greenhouse 20M² could you if you play me provide the layout of the card to be made under any format (pdf, eagle, proteus or other )
thank you very much

jean pierre gauthier 8 years ago

I wish to realize a card like yours without too much SMD. To do this I need the files that correspond to the turntables that you propose at the top.
Once realized I will try to add a bit of code to manage an alarm on 1 or 2 level of temperature
Jp.perso@wanadoo.fr
Thank you Best regards

ifriad 8 years ago

Hi Jean

Please send me your email and I will send the files you need.

My original unit is a little differne than the published unit. The gus at Elektor did improve my design and code but for the PCB they used a lot of SMD including the PIC microcontroller. My original code uses through in components.

Please let me know what would you like to have.

Ihab

2 Comment(s)

TimUiterwijk 11 years ago

Currently working on rewriting the software to more open C code, since MicroC requires a license.

Using more open C makes the software more easily adaptable to other platforms

midon 11 years ago

Was reading the related article in the November 2013 issue of the magazine (congratulations on being published by the way) and noticed that the article quotes DS18S20 sensors rather than DS18B20 sensors as used in your project. Did you make a code change to do this? Couldn't help but notice that figure 2 of the article says DS18S20 but that the family code shown in the LSB is for a DS18B20.

TimUiterwijk 11 years ago

Small bug fixed in software. New version uploaded

TimUiterwijk 11 years ago

No, we indeed had that plan, but later changed it back to the original. 6 pins, 6 sensors.

ifriad 11 years ago

Hi, I guess the currently implemented circuit is different from my original. In the original design each sensor was connected to the uc in an independent line but I was later informed that you will change that and make all sensors share the same data line, that is why I was asking on modifying the mikroC code. Cheers Ihab

TimUiterwijk 11 years ago

Hello Ihab, I did not change anything in the mikroC code, so that remains the same. Best regards, Tim

ifriad 11 years ago

Hi Tim, Could you please post the modified circuit. I guess it is will also be interesting if you can update the mikroC code as I think it is easier to understand for those who are not professional uc programers as myself. Thanks for the updates. Cheers Ihab

TimUiterwijk 11 years ago

Software writing done. Software added to project

7 Comment(s)

ifriad 11 years ago

The first unit was build to monitor the temperature variation at different points in a concrete slap just after the concrete was molded and during hardening. That was for an M.Eng. student. The unit was very primitive it only had the keypad and the LCD. The logging was done manually every few hours for a couple of days.

0 Comment(s)

NECV20 11 years ago

If you put the sensors on a vertical stick at 1,5, 1,0, 0,5, 0,1 meters above the ground and the lower two sensors in the ground, you get a good idea of the temperatures in your garden.

This is interesting for detecting nightfrost for low plants.Temperatures at 1,5 meter may still be above 0 celsius (official hight for measuring meteo temp.) but it can freeze nearer to the ground.