Wednesday, May 1, 2013

DIY Geiger Counter with Nokia 5110 (3310) LCD and PIC16F876A; new prototype!

It starts here, but now I tried to work with Nokia 5110 graphic LCD. The problem I met was there no ready library for my PIC compiler! It's mean that I was forced to write my own procedures to initialize the lcd, clear screen, write texts and etc. After searching the web I found some arduino examples from sparkfun  and lcd datasheet. With Arduino library it was very simple to run this display, but my project build with PIC16F876A and I started to transfer the principles to my mcu. This forum thread was helpful for understanding how to write main display procedures. The results are in the current video. This is diy geiger counter prototype. It use only PIC16F876A for controlling all dosimeter functions. I transferred almost all program functions from version with 16x2 lcd to this version of the board. The hardware include voltage reference IC for precision voltage measurements.

The prototype work started from this:

And comes to this:

1. PWM control high voltage, the output can be tuned with 2 keys from 300V to 600V.
2. Measurement period automatically changes, depend on radiation level. See on the video how it happen when level goes up and down. Long period is better for the background.
3. Fast response scale on the display will show immediately levels changes, even before the measurement period will end. It useful when prompt response is required. The bargraph scales up to 800 cpm.
4. As before  UART, Arduino, Geiger Bot communication
5. Calibration menu (not presented in the current video) allow to changed conversion factor, alert threshold, high voltage and save all settings.

This work still in progress. Because the signal captured from tube cathode there is some problem with sensitivity to static electricity (if you touch the tube it will cause false counting) I think I need to make some small circuit changes. But if enclosure is used its unnecessary.

follow for updates... 

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