My Valentine One to PC research

**zPilott** · 04-04-2005, 10:31 PM

I have been working on this interface for a while (bout a year an a half), but, due to a lacking of hardware knowledge, I still haven't gotten an interface that I like. My first attempt was using an adapter from http://www.compsys1.com/workbench/On...3_adapter.html.

It worked, but I wanted a usb solution, and I have been chasing it unsuccessfully ever since.

I found a usb adapter USBMOD3 that looks like I could use it to do what I want and made an adapter that looks a little like this:

. The first one I made I was getting some data back from, but it didn't make sense. It was now sending a bit of data then quitting ( the serial connection with the max232 would continuously transmit). It also wasn;t extinguishing the V1 display. I thought it was a problem with my interface, but I later checked out my remote display, and it didn't work either. I tried hooking it up with different cables and the remote worked, but now I can't find the original adapter that I made (it got lost in my 2000 mile move, I guess). I tried making another one, and I am getting NO output from the V1 in my application.

Anyway, I probably woudl have had this all done a long time ago, but I have been asking for help from the wrong people. I am a software guy (I make video games) and I don't know much about the hardware. I have failed to get any of my friends who have the knowledge interested. I need to ask for some advice from the peopel here on the forum who have an interest in getting somethign like this.

I have spend a bit too much time on the software, but I don't have the hardware interface. My program is easily skinnable, and all the info is exported via a dll so that any application can use it, even multiple applications simultaneously (for integration into front ends, gps software, logging, etc.)

Lets knoock this out, the answer is not too far away.

**drait** · 04-05-2005, 10:39 AM

zPilott, that's great that you're getting back into this interface. I remember reading about your first serial version. With you and jimbonzzz doing V1 software, it can only help to inspire more hardware development. I'll read up on the USBMOD3 and see if I can contribute anything.

EDIT: Also, according to Jim's schematics, a resistance value of at least 3.6k is necessary to turn off the V1's display and send the display signal to the concealed display if you don't have one already hooked up. If you do, you should be able to use an RJ11 splitter and forego the need for the resistor loop between +12V and the data line (looks like you've got a 2.2k between +5V and data).

This USB interface looks promising (and simple to boot!).

EDIT2: Is your diode facing that direction intentionally? If I'm reading it correctly, that's the RXD line, and if you have the cathode on that side, wouldn't it be blocking the signal?

**zPilott** · 04-05-2005, 11:29 AM

josh -
The bottom half of the pic is from the V1 docs. I added an extra trace that I forgot to put on the pic, for the +5 volts. This is supposed to turn off the display on the V1, but that isn't happening. I personally can't tell you why it is there, but this is an email I received from a friend because I asked if it was necessary to be there:

The 10K you are probably alright to leave out, but if you can squeeze it in somewhere it wouldn’t hurt…It is a current limiting resister. If for some reason your USB board blew up and shorted the V1 to ground you would get a large current spike that could damage the V1s output driver.

On the data side, I checked the voltage across the receive and ground pins, and got something just below 5V. I got a new multimeter that measures Hz, and I can see a flurry of activity when the V1 is sending out data, then nothing (I swear that it used to send out continuously). I am setting the baud rate to 5958, but I can't seem to find a way in the usbmod API to verify if it actually is getting the correct baud rate. It seems to me that using the multimeter will only tell me if something is being sent. The signal from the V1 is idle about 25% of the time. Maybe I should have gotten the more expensive one with the min/max value as well as the average, it might help here.

Anyway, I don't seem to be getting any data to the USB chip, even though there seems to be activity. I am still confused as to how I could ever get a start bit (0V) with the circuit the way it is.

The last time I made this circuit, I was getting consistent garbage data back (it was 99% the same every time I turned on the V1, but the data coming back was malformed). I had taken out my remote display when I installed my carPC, and didn't reinstall it for some time. When I did, it seems that my hardwiring kit went bad, because, while the V1 still works with it, the remote display doesn't. If I hook it up via the cigarette lighter, the remote display does work. The V1 docs say to not display anything if it receives malformed data, so I was hoping that I was getting what was actually on the line, which was garbage. I tried to find my old interface, but it is either lost, or buried in one of the moving boxes we aren't planning to unpack until July.

drait - thanks for any help you can offer.

I don't know if connecting the V1 to the +5 V on the USBMOD chip is bad. I also was having trouble finding the right capacitor, so I used a .047uF, and I am not sure if this would be a problem.

Also, I think my software is working properly. I made a standalone loopback circuit (similar to the top portion of the drawing, but tying 27-28 together, and not connecting the V1 at all) at it worked.

**zPilott** · 04-06-2005, 12:24 PM

I will try it out tonight without the 10k.

I was looking at Fry's at the frequency generators and oscilloscopes, but they are way out of the ballpark on price. I have already asked everyone that I can think of, but no one I know has one that I can borrow.

**zPilott** · 04-08-2005, 11:58 AM

the serial interface looked something like this:

but without the RD piece attached. It was connected to an A232DB adapter from http://www.compsys1.com/workbench/On...3_adapter.html

this is the schematic for the adapter that I used.

I had it working on the breadboard, but I tried to make a small pcb a couple times, and they didn't work, which is another reason why I tried to pursue the USB solution