USB to TTL help

[woody]

I have an old GPS unit from an OnStar system and have a couple of diffrent schmatics to hook it up to a computer. My problem is they all call for the RS232 shifter, namely the one from from sparkfun. Any ideas on how to convert that idea to a USB type of shifter as well as being able to use the ground and 5 volt side to power the unit? Any help would be appreciated.

 

[3v0]

Are you taking about the SparkFun USB Bitwacker? If so are you not wanting to use it because of current limitations.

How much current does the OnStar system draw ?

 

[woody]

Are you taking about the SparkFun USB Bitwacker? If so are you not wanting to use it because of current limitations.

How much current does the OnStar system draw ?

Not the SparkFun USB Bitwacker but rather like the RS232 Shifter, just with an USB plug, not the RS232 connector. It will need 5vdc. Here is a link to what I am trying to achieve. CLICK HERE

 

[ClydeCrashKop]

It looks like those programs are using COM1. Unless you can find a USB program or write one that can interface to Google, I would stick with RS232.

 

[3v0]

No Porgramming Solution

On the PC make the USB look like a COM port. Use a USB>RS232 converter to connect to RS232 shifter which connects to OnStar.

PC side
Microchip has a PC device driver that uses USB but creates a virtual COM port. It will let you use a PC program written for RS232 with a physical USB connection. The UBW instructions help you find and install it.

OnStar side
Get a USB to RS232 converter. If it does not provide the +5 you can open the cable and get it as described in the link you provided.

Power for the module is obtained from a PC USB port. Take a scavenged USB cable and connect the red wire to both the module's +5V pin and the VCC pin of the RS232 Shifter [see diagram above]. The black USB wire is connected to the GND pin of the module and the GND pin of the RS232 Shifter. Now attach the RS232 Shifter to the PC's DB-9 serial port and connect the shifter's RX pin to pin 8 of the module and the shifter's Tx pin to the module's pin 9. Finally, plug the GPS antenna into the module.

Should work and there in no programming.

Most any USB>RS232 converter should work because only the RX and TX signals are used.

 

[woody]

Cool, thanks for the help. What did you guys think of the idea on using the onstar gps module?

 

[3v0]

Cool, thanks for the help. What did you guys think of the idea on using the onstar gps module?

Depends on what you are going to do with it?