Beginner Serial + MAX232 Question

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1

Hello,

I am a programmer learning electronics through SparkFun’s tutorials.

I am now at [Tutorial #4 and I am trying to set up a loopback serial connection using the MAX232 chip.

http://www.sparkfun.com/commerce/images … /UART1.jpg

I have set up (to the best of my knowledge) the circuit above, but it does not seem to echo back the characters I type in my terminal.

Here is my circuit WITHOUT the wires going out to my serial port:

[

And here is my circuit after plugging in lead wires which are connected into my serial port:

[

I have been looking and fiddling around with this circuit for the past few hours with out any success.

Can anyone of you guys spot a mistake in my circuit?

Thanks in advance, :slight_smile:

Chris](ImageShack - Best place for all of your image hosting and image sharing needs)](ImageShack - Best place for all of your image hosting and image sharing needs)](Beginning Embedded Electronics - 4 - SparkFun Electronics)

2

Sure you have the RX/TX pin wiring correct on the DB9 side?

You can try flipping it as a quick test.

3

Try bridging pins 2 and 3 on the DB-9 connector, to make sure that your terminal software is working and your cable isn’t broken.

The MAX232 requires bigger capacitors than 100n. Use the MAX202 if you want to use 100n.

Leon

4

Also you may need to loopback DTE/DCE or RTS/CTS in order to get the terminal program you’re using to think that there’s a device present to talk to.

5

Thanks for the replies !

The wire I was using to create the loopback was damaged… Go figure… :slight_smile:

I swapped the wire and it works perfectly !