RPM

Digital RPM indicator

IMAG0008

I made a circuit for RPM measurement based on an Atmel ATtiny24 to drive a Hitachi 44780 parallel interface character LCD. It uses an external interrupt request and INT0 to calculate the elapsed time between high/low transitions on the INT0 pin. The elapsed time is then converted to RPM and sent to the LCD. The code will work from RPM values up to 999, and a variable timeout is used for a low cutoff to display 0RPM. The RPM range could be extended to 9,999 or higher by modifying the decimal to BCD routine at the end of the program.

Sony 016

Here is the source code, it compiles with AVR Studio and AVR-GCC. › Continue reading

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Wednesday, August 26th, 2009 Electronics 7 Comments