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Portable temperature and air humidity loger with LCD display - ATIV
Revision: 1.2
Date: 28.02.2005.

This device is intended for autonomous measuring and storing temperature and relative air humidity data, without PC. It has enough memory for 3 continuous years of measuring.

Click here to see ATIV device photo GALLERY

Fizicki izgled uredaja

Device is constructed in order to be used as portable temperature and air humidity measuring unit. Usage of SHT11 sensor makes this device a serious candidate for overrunning boundaries of amateurism. Important feature for this sensor is that it needs no configuring, and is very accurate and precise in measuring. This device has user-friendly menu for configuring the parameters, preview mode for viewing non-saved measured values, and is able to transfer saved data to PC using RS232 interface.

Device characteristics:

Power supply: 9V (30mA-150mA, depends on LCD back light intensity set)
Display: Smart LCD module (Hitachi HD44780 compatible) 2x16 characters
Measuring sonde: Intelligent sensor for temperature and relative air humididy measuring, SHT11
Commands: Four push buttons: LEFT, RIGHT, UP, DOWN
Data storing: Internal 64kb EEPROM memory is used, which is enough for 3 years max of continuous work time.
Measuring: Temperature: -40 °C - 99°C; Humidity: 1 - 99%
Accuracy: Temperature: ±0.5°C at 25°C Humidity: ±3.5 % RH
Measuring resolution: 0.1°C Temperature and 0.1% RH
Real time clock: Internal, with back-up batrery
Others: Optional full memory alarm, LCD display back light setting, preview of stored data on device display, PC link for data transfer...

HARDWARE: rev 1.2

Device consists of PIC16F876A microcontroller, EEPROM memory 24LC512 (64x8 kbites), Dallas DS1307 RTC, and RS232 voltage adaptation circuit. LCD is connected to device in 4-bit mode, so it uses minimal number of microcontroller pins, that is, 6. Device also has BUZZER, which is used for audible indication when some of push buttons are pushed. It is also used for audible warnings when memory is full, or for similar actions. Electrical schematic for this device is shown on picture 1.

Picture 1. Electrical schematic
Click on the picture left to open detailed PDF file with schematic.

Picture 2. ATIV v1.2 device PCB
Most of components are placed on PCB. LCD is connected to connector SV2. Connector SV3 is used for connecting SHT11 sensor. BCK_K pin can be connected (optionally) to LCD back light CATHODE, which enables the LCD back light setting feature.

You can download zip archive with PCBs from here.

ATIV v1.2 device front layout.
Click on the picture to download PDF file.

FIRMWARE ver 2.0


Picture 3 shows basic display at device start up. If you press UP button, device will start storing measured values at preset period. Display will indicate that sampling is in progress and will periodically show current session number (BZ), number of stored samples (RN) and memory left, etc, in bottom left corner, instead of current date. If we stop storing by pressing DOWN button and then press UP button to start storing again, session number (BZ) will increase by one, which eases later searching and browsing through database in case we have multiple measuring points (places). Record Number (RN) shows number of total samples stored.

Picture 3. Main view on ATIV v1.2
Current time is shown in upper left corner of LCD. Current date is shown below current time, i.e. in bottom left corner. Measured temperature is shown on the upper right, and bottom right corner shows relative air humidity in percents.


You can adjust device settings easily, using LEFT or RIGHT push buttons. By pressing LEFT or RIGHT button we enter menus 1 to 9, that are shown in a table below. Adjusting of desired parameter is done by using DOWN and UP push buttons. If push buttons are inactive longer than 8 seconds while we are in some of nine available menu sections, LCD will display back the main view.

Menu sections available in current firmware version are shown below:

Menu #
LCD menu display
Menu description

Real time clock setting (Push buttons UP, DOWN, LEFT, RIGHT)

Selecting a period of sampling (push buttons UP, DOWN). Total time available for recording (depends on available memory) is shown in upper right corner.

If you want to delete everything from memory, you should press UP and DOWN push buttons simultaneously in this menu section.

This menu section shows memory left. 100% means that memory is completely empty. (This menu section is informational, thus it offers no adjustments)

If MEMORYFull alarm is on (ukljucen), you will hear sound warning when memory is critically full. (Settings are done by pressing down UP or DOWN push buttons).

If buzzer (bipper) is on (ukljucen), your actions with device will have proper sound indication. Note that buzzer must be ON for memory alarm to work.

Info menu. This menu section shows info about current session number (BZ), total memory used (MEM), number of samples recorded (RN), Samling period (PS), etc...

Adjustments for LCD back light intensity. It is useful for battery saving, if device is not powered from main supply.
9. If AUTONastavak is ON (ukljucen), in case power suddenly goes off, device will continue work as soon as power is restored, without any disturbance in sampling.


If you push both LEFT and RIGHT push buttons simultaneously while on main view, you will enter sessions preview menu, form which you can preview stored sessions on device. Now you can select session number and then, by pressing RIGHT push button, you can enter at start of that session. Now, using UP and DOWN push button, you can browse through database with time and date shown on display. When needed entry is found, pressing down the RIGHT push button will display numerical and bar-graph preview of measured temperature and air humidity for selected date/time. LCD display for this menu is shown in table below:

Menu #
LCD menu display
Menu description

Choosing the needed session number (BZ) (UP, DOWN push buttons)

Browsing through date/time database using UP, DOWN push buttons.

RIGHT push button enters preview of measured values for selected date/time.

Simultaneously pressing down the LEFT and RIGHT push buttons exits this menu.

SOFTWARE: ver 1.6.02 (august 2004.)

We have created special applications for connecting and using ATIV device on PC, ATIV Komunikacija and ATIV Analiza. Both of these two applications can be found in install package, which can be downloaded from the link below. First application offers real time tracking of measured values, displayed on PC (Picture 4.1), reading and storing data from device to PC, exporting data into DTS or RTF file format (Picture 4.2), and tabular preview of stored values. It also allows you to check device status, i.e. sampling period that is set, memory left, number of sessions... (Picture 4.3). Useful tool this application also offers is device's real time clock synchronization with Windows time on PC (Picture 4.4).

Picture 4.1

Picture 4.2

Picture 4.3

Picture 4.4

Click on desired picture to enlarge it.

ATIV analiza is application that allows graphic preview of stored data. It features basic functions for graphic manipulation: zoom, moving and selecting a specific session from saved DTS file. You can also print your graph, which completes your documentation about measuring.

Picture 4.5
This picture shows ATIV Analiza application, which allows graphic preview of DTS files, that are exported from ATIV Komunikacija application.

Click on picture to enlarge it.

Installation archive for ATIV software (WinXP, WinME, Win98) can be downloaded from here.

Firmware is not free, so, if you are interested in ordering HEX file, you can contact me at:

If there are some unclearnesses about this project, feel free to contact me at:

© 2014 all rights reserved by ePraktikum design by Pinky Poslednja promena: 06 Jan 2014. 12:01:02