SCI to Serial/USB cable How to?

[1BADVAN]

I was thinking with all the stuff being made like SMEClog and the plugins for logworks to datalog with our computers someone could make a tutorial on how to make the SCI to serial/usb cables.
I get how to do it but have some major questions on how to choose the right board.
Another thing is that if we can USB the board could be powered by that eliminating the power line level converter Also i know shel game builds them for about $50 - $65 but from what i can see is if you eliminate the sci connector and just use push terminals you can build one for as cheap as $15

[1BADVAN]

like this http://cgi.ebay.com/USB-To-TTL-Conve...3%3A1|294%3A50
it has a power output so obviously it does not need a power supply

[risen]

That may work, but you have to make sure it can handle the inverted TTL signal.

I've been using the same module I have a writeup on in the KC for LM datalogging interfaces for SMEC bench testing, so I can tell you that it works. You just need to configure it to do inverted comms and you only need the tx/rx wires hooked into the sci port. You don't need to do anything with power or ground. I'm going to do a writeup for the SMEC eventually, but I can try and help you out with your setup if you'd like.

[1BADVAN]

Thanks for the help! So what do you mean exactly by inverted comms do you just hook the wires up differently or to you have to flash the chip, or is it a setting on the computer like in windows

[1BADVAN]

i read your KC post and see the program that you need I am guessing i would need to check the inverted signal boxes is what you mean

And does it matter if there is another USB cable between this and the computer or can this plug right in?

[ShelGame]

I was thinking with all the stuff being made like SMEClog and the plugins for logworks to datalog with our computers someone could make a tutorial on how to make the SCI to serial/usb cables.
I get how to do it but have some major questions on how to choose the right board.
Another thing is that if we can USB the board could be powered by that eliminating the power line level converter Also i know shel game builds them for about $50 - $65 but from what i can see is if you eliminate the sci connector and just use push terminals you can build one for as cheap as $15

It won't be that much when I get them done (boards have been shipped!).

Like Risen said, my original instructions for the Minidash interface were wrong. I didn't realize the signals were inverted (which just means that a 'high' signal is considered 'low' and vice versa - ie, 5v= 'high' and 0v='low').

The cables I'm building will be 100% plug-n-play, into the SCI connector. No figuring required.

If you want to do it DIY, it's not really that tough - especially for USB. FTDI makes a cable with their chip built in, powered from the USB port, for $20. And, you can invert the inputs with a software setting (as you noted). For the SMEC, that works fine.

But, for the SBEC, an additional protection cicuit for the Rx line is required becuase the Rx and bootstrap lines are multiplexed. You want to keep the 12V off the Rx line, if possible.

[risen]

i read your KC post and see the program that you need I am guessing i would need to check the inverted signal boxes is what you mean

And does it matter if there is another USB cable between this and the computer or can this plug right in?

Yes, checking the 2 boxes is exactly what I'm talking about.

To answer your previous question I believe that the TTL signals are normally at 0v and get pulled up to 5v to signal, and inverted means that they're normally held @ 5v and get pulled down to 0v to signal.

To use the module you need a A to mini-b USB cable, it won't directly plug into your laptop. Those types of usb cables are commonly used for cameras and cell phones. There's a link to a 6ft cable from mouser in the article so if you don't have a cable laying around you can order both at once from mouser.

[jeeper]

Would something like this work as-is with MPScan? http://www.ebay.com/itm/USB-2-0-DB9-...965#vi-content