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Serial Port Prototypes Answered

Has anyone made a serial port interface? I would like to build a rpm meter using a serial port of my laptop. The schematic should be easy but I can not find any information on it. Any ideas? Thanks, Brian

3 Replies

Goodhart (author)2007-10-09
gmoon (author)Goodhart2007-10-11

Let me elaborate on Goodhart's comment:

Possibly because it's obvious to most hardware guys, he neglected to mention that most modern microcontrollers have serial protocols built-in (two of the 4 links above use Atmel controllers.) So AVRs or PICs are great platforms for starting this type of project.

You generally need a rs-232 'glue' chip (MAX232 project) to convert the uC voltage to normal serial.

Some more modern serial ports can deal with 5 volts, however. I've used the E-Lab EDE702 LCD driver, which is based on a PIC. It uses a 33K current-limiting resistor to drop the rs232 voltage. Worked fine for me, so a similar approach might work...

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