Arduino used as USB to RS323 Adapter

Hey guys, just got my Arduino UNO boards last week and have yet to have a chance to work with them. Last night I ran into a problem when I realized my computer does not have a RS323 serial port that I need. Unfortunately I do not have the luxury of time to figure all of this out on my own, so I am looking for some help to build a quick and dirty USB to RS323 adaptor until my proper bale comes in the mail in a couple weeks.

I have a Arduino UNO R3 and plenty of spare components to around. I also have a MAX202. Would I need anything else? Where do I start?

Looks like just handful of 0.1uF caps. Wire it up per the datasheet, page 11. https://datasheets.maximintegrated.com/en/ds/MAX200-MAX213.pdf What's the RS232 for? Let the Uno talk to something else? Connect D0, D1 (but can't use USB to PC at same time) or use 2 other pins and one of the software serial libraries. Don't forget to connect Gnd as well.

All you need are some caps, the MAX202 datasheet, and a better spelling of the RS232 interface! Build up the circuit as datasheet shows, connect rx and tx to digital pin 0 and 1, connect 5V and GND to the chip and connect reset pin to ground. Should work.

Cheers, Ale.

P.S.: CrossRoads was more fast than me!

Ceramic caps should work for this, right? I don't have any electrolytic as small as 0.1uF.

Never mind, I found the proper caps.

Well I didn't get this finished and working in time, but I am still trying to get it to work.

Right now I have the IC wired up as described in the datasheet.

I am not sure if I have all the inputs and outputs connected as I should, but this is what I have:

MAX202 Pin 7 RS-232 Output -> Arduino TX MAX202 Pin 8 RS-232 Input -> Arduino RX

MAX202 Pin 9 TLL/CMOS Output -> Device Data In MAX202 Pin 10 TLL/CMOS Input -> Device Data Out

Arduino Ground -> Device Ground Arduino Ground -> Arduino Reset

Alley_Cat_Jack: MAX202 Pin 7 RS-232 Output -> Arduino TX MAX202 Pin 8 RS-232 Input -> Arduino RX

This ones have to be swapped, rs232out -> arduino rx and rs232in -> arduino tx .

Ciao, Ale.

Sorry, I wrote that down wrong. This is what it’s wired as:

MAX202 Pin 7 RS-232 Output → Device Data In
MAX202 Pin 8 RS-232 Input → Device Data Out

MAX202 Pin 9 TLL/CMOS Output → Arduino RX
MAX202 Pin 10 TLL/CMOS Input → Arduino TX

Arduino Ground → Device Ground
Arduino Ground → Arduino Reset

Seems ok, how do you make the test? Try using serial monitor to make a loopback test : first remove the rs232 interface and short pin 0 and pin 1 of arduino : when you send a string should echoed back in the monitor. If this works, reconnect the interface and try the loopback on the rs232 side.

Ciao, Ale.

Jumpering Reset to GND is supposed to put it into USB to TTL mode. Is that not what I should have ti set up as?

What device is the RS232 interface connected to?