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By jschwalbe
#196180
Greetings! I'm trying to accomplish this: https://github.com/matlock08/homesecurity and as such am contemplating the purchase of a MAX3232.

In reviewing the product info at https://www.sparkfun.com/products/11189 I can't tell for sure if it's going to work the way I think it's going to work. The board I'm attaching to apparently has 12V logic ( 0 to +12V? ) which of course needs to be converted to 3.3 or 5 if I want to use it for anything useful.

Is this the right unit to purchase?

Many thanks!
By Valen
#196211
RS 232 is based on positive and negative voltages of the same swing. So your device would probably send +12 and -12 volt instead. This MAX3232 would convert those incomming voltages on RX safely to TTL levels between 0 and positive supply voltages (+3.3v or 5 volt or whatever above 2.7 volt that you put on the Vcc pin). However, it will not send out more than about 5.5 volt on the TX pin. So your board may not work reliably if it expects 12 volt at least. IIRC, the minimum voltage swings for RS232 communication must be larger than + and minus 3 volt so it is probably ok. Unless you have substantial voltage drops along long wires and/or crappy shielding in a electrical noisy environment.