Problems with homemade RS232-to-TTL converter board based on TI's MAX232

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April_21
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Problems with homemade RS232-to-TTL converter board based on TI's MAX232

Postby April_21 » Tue Oct 18, 2016 8:22 am UTC

I've designed an RS232-to-TTL converter board based on TI's MAX232 IC that I plan to use to program a few custom Arduino boards that I have. However, I'm having trouble with the board and I'm hoping that someone can help me debug it.

First, let me show you my setup, below.
Eh...I didn't see how to add a image...

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Felstaff
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Re: Problems with homemade RS232-to-TTL converter board based on TI's MAX232

Postby Felstaff » Tue Oct 18, 2016 10:23 am UTC

I think you need to add 5 posts before being able to add images, but perhaps once approved, you should be able to add images by:

  1. Pasting an image URL, highlighting it, and selecting the Image button
  2. Code: Select all

    Typing in [img]#[/img] adding in the image's URL where the # is
  3. Selecting the Image tab and add an image from your personal computational device of choice.

If you can't do any of these, make a few posts within the general forum until your post count reaches 5 (some subforums don't increment post counts, so why not introduce yourself and post a fleeting thought or three.
Away, you scullion! you rampallion! You fustilarian! I'll tickle your catastrophe.

KnightExemplar
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Re: Problems with homemade RS232-to-TTL converter board based on TI's MAX232

Postby KnightExemplar » Tue Oct 18, 2016 2:37 pm UTC

April_21 wrote:I've designed an RS232-to-TTL converter board based on TI's MAX232 IC that I plan to use to program a few custom Arduino boards that I have.


As have literally everyone else I've met who has ever done this. The RS232->TTL converter is a must have for beginners, but I think that maybe the number of pins is too much for a beginner. It really can be anything from poorly soldered connections, backwards capacitors, or a poorly made DB9 connector that will screw you over.

Here's a transistor version that is much simpler to assemble: https://www.sparkfun.com/products/449

No capacitors, and only like 4 pins or something.

I know that the Max232 is the legitimate industry standard way of doing things (It uses a charge-pump capacitor design to boost voltages to the industry standard levels). However, the above transistor design from sparkfun is simpler to assemble and has fewer parts. Its better for a beginner, even though it will only work with computers / arduino. (The transistors steal current from the Tx / Rx pins. Very non-standard)

Despite the non-standard approach, it has worked every single time for me.

------------

If you want a 100% legitimate solution, Sparkfun sells Max3232 breakout boards, which works for 3.3V and 5V projects.

https://www.sparkfun.com/products/11189

Capacitors already soldered on. Just gotta get the DB9 connector right and you should be set.
First Strike +1/+1 and Indestructible.

April_21
Posts: 5
Joined: Tue Oct 18, 2016 6:21 am UTC

Re: Problems with homemade RS232-to-TTL converter board based on TI's MAX232

Postby April_21 » Fri Oct 28, 2016 6:52 am UTC

Thanks a lot!
Felstaff wrote:I think you need to add 5 posts before being able to add images, but perhaps once approved, you should be able to add images by:

  1. Pasting an image URL, highlighting it, and selecting the Image button
  2. Code: Select all

    Typing in [img]#[/img] adding in the image's URL where the # is
  3. Selecting the Image tab and add an image from your personal computational device of choice.

If you can't do any of these, make a few posts within the general forum until your post count reaches 5 (some subforums don't increment post counts, so why not introduce yourself and post a fleeting thought or three.

April_21
Posts: 5
Joined: Tue Oct 18, 2016 6:21 am UTC

Re: Problems with homemade RS232-to-TTL converter board based on TI's MAX232

Postby April_21 » Fri Oct 28, 2016 7:01 am UTC

You mean this kind of transistor version ?
Image
KnightExemplar wrote:
April_21 wrote:I've designed an RS232-to-TTL converter board based on TI's MAX232 IC that I plan to use to program a few custom Arduino boards that I have.


As have literally everyone else I've met who has ever done this. The RS232->TTL converter is a must have for beginners, but I think that maybe the number of pins is too much for a beginner. It really can be anything from poorly soldered connections, backwards capacitors, or a poorly made DB9 connector that will screw you over.

Here's a transistor version that is much simpler to assemble: https://www.sparkfun.com/products/449

No capacitors, and only like 4 pins or something.

I know that the Max232 is the legitimate industry standard way of doing things (It uses a charge-pump capacitor design to boost voltages to the industry standard levels). However, the above transistor design from sparkfun is simpler to assemble and has fewer parts. Its better for a beginner, even though it will only work with computers / arduino. (The transistors steal current from the Tx / Rx pins. Very non-standard)

Despite the non-standard approach, it has worked every single time for me.

------------

If you want a 100% legitimate solution, Sparkfun sells Max3232 breakout boards, which works for 3.3V and 5V projects.

https://www.sparkfun.com/products/11189

Capacitors already soldered on. Just gotta get the DB9 connector right and you should be set.

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Soupspoon
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Re: Problems with homemade RS232-to-TTL converter board based on TI's MAX232

Postby Soupspoon » Fri Oct 28, 2016 11:25 am UTC

Umm.. April_21, are you top-posting, there? A bad habit1, IMO. You'll note that it's Question then Answer order on the forum (most forums). And that if it's viable to edit down what you're replying to, not just leave the whole thing hanging out below, apparently unnecessary.

Apologies for not helping you directly, but I'm already watching this thread for my own tangential interest in the subject. Consider this a PTW. I may add something on-topic, but so far I'm not able to compete.

1 I blame Outlook Express in the '90s for inverting all the common prior standards because "Microsoft knows best", although it's at least a logical ordering for real-time aggregations like Twitter feeds.

KnightExemplar
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Joined: Sun Dec 26, 2010 1:58 pm UTC

Re: Problems with homemade RS232-to-TTL converter board based on TI's MAX232

Postby KnightExemplar » Sat Oct 29, 2016 11:51 pm UTC

April_21 wrote:You mean this kind of transistor version ?
Image


I really don't know what you're talking about, at all.

My advice was basically buy this thing: https://www.sparkfun.com/products/449
First Strike +1/+1 and Indestructible.


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