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[on:]

I'm trying to interface this rs232 serial card reader(female db9 port, port powered) with my USB Arduino. (I know there are other/better ways to interface with a card reader, but this is all I have at the moment and I'm trying to get a prototype out the door ASAP)

I'm played around with the ttl to rs232 adaptor , but had no luck (presumably because it's designed to hook into a computer's rs232 port, or at least a powered port)

I've seen alot about the max232 chip, but I'm not sure that it's going to help me.

Any suggestions to get something running with the supplies I have? Thanks!

[Reply #1 on:]

Extensive information for this sort of project at...

http://sheepdogguides.com/arduino/art4SeIntro.htm

[Reply #2 on:]

The reader is "port powered",  so you'll need to supply about 9-12V on DTR and/or RTS to power it (probably:  it's really chickenbleep of SparkFun to not document where the reader gets its power  >).

Something like a TTL-to-232 converter could be handy,  but you don't really need it because you're not transmitting.  A simple 1-transistor inverter will suffice for dealing with the data coming in from the reader.  You can steal the design from some versions of serial Arduino,  or from any of various other simple single-board computer designs.