GLK12232-25-SM with RS-232 and TTL Serial

knightofoldcode · Post by **knightofoldcode** » Wed Jan 12, 2005 3:20 pm

I'd like to setup my display so that I can use RS-232 on my PC and TTL on my basic stamp. The intention is to ultimately put my display into a container with a Basic Stamp, but the BS needs TTL levels, (I guess I could design a circuit, but why when the display already has the TTL levels?) therefore I would like to solder on a pair of wires onto the pads, and use those for the TTL levels, and the initial header with the power connector for RS-232 with full 12V swings.

So do I solder to A and B (as I would assume), or some other combination?

TIA,
Knight.

Tom · Post by **Tom** » Wed Jan 12, 2005 3:59 pm

Thanks for posting at Matrix Orbital.

You wouldn't be able to control the unit via TTL and RS-232 by hooking up both protocols. You can only use one or the other protocols. The reason for this is TTL and RS-232 are using the same TX and RX lines. If you have TTL while having the RS-232 jumpers on, there will be a conflict. The RS-232 chip will pull some of the voltage levels.

You would be able to use the I2C protocol with RS-232, but not TTL and RS-232.

Best Regards,

knightofoldcode · Post by **knightofoldcode** » Wed Jan 12, 2005 7:00 pm

Tom wrote:Thanks for posting at Matrix Orbital.

You wouldn't be able to control the unit via TTL and RS-232 by hooking up both protocols. You can only use one or the other protocols. The reason for this is TTL and RS-232 are using the same TX and RX lines. If you have TTL while having the RS-232 jumpers on, there will be a conflict. The RS-232 chip will pull some of the voltage levels.

You would be able to use the I2C protocol with RS-232, but not TTL and RS-232.

Best Regards,

I guess I didn't explain what I wanted to do well enough.

I understand that I can't run BOTH rs-232 and TTL at the SAME TIME, but I'd like to be able to switch between TTL (Basic Stamp) and rs-232 (PC), without having to solder and unsolder two solder pads each time I need to take the screen off of my Basic Stamp and put it onto my PC.

Knight.

Tom · Post by **Tom** » Thu Jan 13, 2005 9:18 am

The explaination I gave is pertaining to you switching from TTL to RS-232 without removing and soldering jumpers. It cannot be done.

I apologize for any inconvenience this causes you. You can have I2C and RS-232 switching though. That can still work for your basic stamp. I believe there is a I2C section in the Basic Stamp manual.

Best Regards,

knightofoldcode · Post by **knightofoldcode** » Fri Jan 14, 2005 10:36 pm

Tom wrote:The explaination I gave is pertaining to you switching from TTL to RS-232 without removing and soldering jumpers. It cannot be done.

I apologize for any inconvenience this causes you. You can have I2C and RS-232 switching though. That can still work for your basic stamp. I believe there is a I2C section in the Basic Stamp manual.

Best Regards,

That's not the answer I wanted.

I misunderstood your response initially. I incorrectly assumed that the solder pads just connected and disconnected the rx and tx lines of the header.

I guess I'll have to look into I2C, although that's alot more crap than I'd like to play with at the moment, I can't even get the display to work with the Basic stamp as of yet.

philium · Post by **philium** » Wed Dec 05, 2007 6:44 am

Could you remove all jimpers & create a circuit that switched between TTL & 233?

Clark · Post by **Clark** » Wed Dec 05, 2007 8:57 am

Hi Philium,

Thanks for your question, sorry to hear that the solder jumpers require a little more effort than you would like to spend. Unfortunately, the solder pads must be connect for one of the protocols that you have listed for the display to work, so it would not be possible to remove them all. If you could design some sort of circuit to switch each of the pads on and off, and manage to solder it to the pads that are on the board, you may be able to avoid changing the jumpers manually. However, should you attempt to connect any circuit of this nature to your display, you would void your warranty. So, if you have the technical expertise to take on a project of this nature, and have faith in your display; go for it, if not, you'll just have to continue switching protocols manually.

Thanks,

Troy