I’m trying to connect rs232 communications to your Lassen IQ GPS board I am using a max3232 chip which is a MAX232 but works at 3.3V and have managed to receive signals on my computer but I can’t seem to be able to transit any thing to the GPS receiver?
I have tested the circuit by connecting the TLL level TX and RX pins of the MAX3232 together and used terminal program to echo a data stream and it all seemed to work fine.
Any help would be most appreciated.
I have managed to get it to work 
by unsoldering the jumper pins that connect the USB RX and TX lines to the module.
It would appear that both USB and rs232 can not live together happily
I would be interested to know why this is if any one out there has an idea.
(Also maybe sparkfun might reconsider their board design as unsoldering jumpers is not very convenient way of setting up things that have to be changed around a lot.)
Yeah, the jumper thing on this board has come up. The next rev should see both solder jumpers and a .1" header footprint for regular jumpers for development.
Pete