I'm looking at the spec sheet on that device,
https://www.electro-tech-online.com/custompdfs/2003/11/MAX232232I.pdf
Page 2 at the top says that the driver ranger is -0.3v to Vcc+0.3v. My input will be as low as -7.6 volts... won't that exceed specifications? I don't think this is right because then you couldn't use a RS-232 signal as an input...
Futher down on page 6, it shows a diagram. Would I put inputs on 10 and 11, tie 14 and 7 to 13 and 8, then use 12 and 9 as my outputs?
Edit: Actually, I guess I could just hook they GPS output (-7.6 to +7.6) to Pin8, which would make pin9 a CMOS output... I am not sure what the terminology Driver and Reciever means, I'm thinking that the "driver" is maybe the CMOS/TTL inputs, and the receiver is maybe the 232 inputs?
I'd be hooking up the GPS to the pin8, which if its the receiver, can handle +/- 30v. Pin 9 would then swing between 0 and 5v (Vs- to Vs+). I think I would then hook up the microcontroller to pin11 and then pin14 would output 0 and 5v (again Vs- to Vs+). That would take the current load off of the microcontroller, and the GPS can accept a 0 to 5v input for signaling.
Vcc = 5v
Vs- = 0v
Vs+ = 5v
gnd = 0v
Pin8 = GPS Tx
Pin9 = MCU Rx
Pin10 = MCU Tx
Pin7 = GPS Rx
And caps...
What are C1 and C2 for? Just for cleaning up internal signals maybe? I'm going to go ahead and lay this out, thanks for reading this. My design project is OOOOHHHHH so close to being finished. Its completely my fault for not having caught this problem sooner. Garmin makes a CMOS in/out GPS and I thought that is what I had, but worry got the better of me before I hooked it up to my microcontroller (thankfully). If we in fact did have the CMOS GPS unit then I honestly believe it would be done by now.
As soon as I lay this thing out and someone confirms (confidentally
) that this should work, I'll lay down my $100 and order my boards
Edit2: Ordered the board yesterday after I REALLY figured out how to wire up that MAX232 (for note, what I have above is wrong and will not work)