Summary of d.i.y. Handheld Multichannel Analyzer (MCA) based on 16F877 PIC Microcontroller and LCD
The author rebuilt a handheld Multichannel Analyzer (MCA) for medical instruments using a PIC 16F877 microcontroller. The system utilizes variable RAM to create a 95-channel histogram, stopping when a channel hits 240 counts. It displays the resulting spectrum as a 30-pixel high bar graph on an LCD screen.
Parts used in the Handheld Multichannel Analyzer:
- PIC 16F877 Microcontroller
- Variable RAM
- LCD Screen
Some time ago I was developing a medical instrument which required histogramming, which got me in the mood to retake my own PIC MCA project(http://home.comcast.net/~prutchi/index_files/scint.htm ).
I used the variable RAM in the microcontroller (16F877), so I limited the number of channels to 95 and let the histogram run until some channel reaches 240 counts (the highest 8-bit number that yields an integer when divided by 8 which is also divisible by the 30 pixel height of the LCD).
The firmware then displays the spectrum as a bar with a maximum height of 30 pixels for each one of the 95 channels.
Click here for complete how-to construction instructions in pdf format.
Click here for a pdf of the schematic diagram for the front-end of the MCA
For more detail: d.i.y. Handheld Multichannel Analyzer (MCA) based on 16F877 PIC Microcontroller and LCD
- What microcontroller was used in the project?
The project uses a PIC 16F877 microcontroller. - How many channels does the histogram support?
The system limits the number of channels to 95 due to available variable RAM. - What is the maximum count value before the histogram stops running?
The histogram runs until some channel reaches 240 counts. - What is the display height for each channel bar?
The spectrum is displayed with a maximum height of 30 pixels per channel. - Why was the number 240 chosen as the limit?
It is the highest 8-bit number that yields an integer when divided by 8 and is divisible by the 30 pixel height of the LCD. - Can I view the construction instructions online?
Yes, complete how-to construction instructions are available in PDF format. - Is a schematic diagram provided for the front-end?
A PDF schematic diagram for the front-end of the MCA is provided.
