Propeller Project Board USB - VGA issues
Moskog
Posts: 554
LA6WNA and I are working on a project that will include several Spinnerets and Propeller boards and a Visual Basic application. The idea is to monitor the state of several ventilation systems placed on different facillities. Older systems that was made before the idea on remote controlling by the Internet. Soon we will have a test system ready and that will be placed on a vent system at the nearby school. The test system will be monitoring only but we plan to make a two-way communication later to be able to make a full remote control of the systems.
We plan to use several Propeller Project Boards USB (#32810) because they are nice and clean and simple to connect to the main PCB's. But we ran into a VGA issue when transferring the project from the PPD-board to the new project board. We plan to be able to use a standard VGA-screen to monitor values on location in addition to the Spinneret but during the tests the VGA screen randomly gets black like it turns off. Usually it gets black after a short, blue blink after reset but sometimes it gets black later in the program code and won't turn on again. We are using the standard VGA_text.spin and VGA.spin without any special effects, just a blue screen with white chars.
The PPB USB board is fed by a 12V 1A supply and the VGA connector is the slim type bought from Parallax. The only thing different,unlike the Professional Board, is that this new board are using different resistor values at the VGA output.
We have tested the board with a VGA-safe code too but with same result, screen turning black. LA6WNA also faced the same issue recently with another PPD USB board, on a different project.
So now we wonder if this is a problem related to the board itself as we can't find anything that could possibly be the reason, are there other people here that has used the same combination, the new board and VGA?
We plan to use several Propeller Project Boards USB (#32810) because they are nice and clean and simple to connect to the main PCB's. But we ran into a VGA issue when transferring the project from the PPD-board to the new project board. We plan to be able to use a standard VGA-screen to monitor values on location in addition to the Spinneret but during the tests the VGA screen randomly gets black like it turns off. Usually it gets black after a short, blue blink after reset but sometimes it gets black later in the program code and won't turn on again. We are using the standard VGA_text.spin and VGA.spin without any special effects, just a blue screen with white chars.
The PPB USB board is fed by a 12V 1A supply and the VGA connector is the slim type bought from Parallax. The only thing different,unlike the Professional Board, is that this new board are using different resistor values at the VGA output.
We have tested the board with a VGA-safe code too but with same result, screen turning black. LA6WNA also faced the same issue recently with another PPD USB board, on a different project.
So now we wonder if this is a problem related to the board itself as we can't find anything that could possibly be the reason, are there other people here that has used the same combination, the new board and VGA?
Comments
Looking at the schematic, I don't see anything going to pin 9... Maybe running a jumper wire from +5VDC to pin9 on the vga connector will help?
I took a look at the schematics of the Propeller Professional Development Board and it seems like pin 9 is connected to 5V there. I also took a look at the Propeller Proto Board (#32212) which I've been used for several projects without any kinds of VGA trouble. Pin 9 is connected to +5V there too. So maybe we have something here.
So, beside the different resistor values on this new board we also have this missing +5V on VGA pin 9.
Ken!
Look forward to hear from the Tech Support team.
Won't be able to test with a 5V jumper until tomorrow, but I will post the result!
It seems that the monitor remains awake, not sleeping, as the green button remains green during blackout.
The monitor is a Dell model nr 1905FP.
Yes, the project was made and tested on the professional board without any problem.
We also tested some other files thats been used with the older Propeller Proto Board (#32212) without any problems, and faced the same issue.
LA6WNA did mention this problem in an earlier thread where he used this new board with his heat-pump project. (In the Project forum)
Does the monitor accept the signalling for that display mode, given on the sync pulses timings and their polarities. Most modern monitors do their signal level clamping on the tail end of the syncs so if the pic content is too early then that could cause problems.
One of my "favorites" is getting the H & V syncs the wrong way around!
Alan
Could it be that your regulator is overheating and shutting down after some amount of time?
Is it just the VGA output that stops? Or maybe the whole system shuts down?
Maybe if you add an LED to the setup, maybe make it blink or something, you could tell...
Or, just measure the 3.3 volt rail when the monitor goes black...
Same .spin-files have been tested on the older boards using same monitor without any problems.
I guess if that happend the display would never act normal at all, now it usually start up at reset and get black after one second, or stays normal for a time or doesn't start up at all.
@Rayman
It is just the VGA, the main loop is up and running like normal. We do have a loop-LED that blinks and the Propeller keeps feeding the spinneret.
What happens if you turn the monitor off when it is black and then turn it back on?
Do you have another monitor you can try? Do you have a scope or multimeter?
Pic showing the bottom side of the Propeller board how the VGA connector is connected to the Propeller.
Rayman, if the screen is black and we restart the program it usually blinks blue or stay blue for a short time before getting black. Sometimes it remains black and sometimes it turns on getting blue and stay blue. Second question, not sure we tested turning off/on the monitor during program-run today. Third question, sorry we haven't tried another monitor today, but LA6WNA used another monitor on his heat-pump project, different but still a Dell. Facing the same problem.
And kuroneko, its hard to believe this is a software problem as the same code ran pretty well on the Professional Developing board using the same monitor.
Sure it wasn't 3.3V you put there?
Good question, we took 5V from the main board. We have a 1,5A 7805 there for other stuff.
You may also want to double check your wiring and check continuity with a multimeter...
I have seen a bad solder connection on a sync signal giving similar effects as you describe.
I think a bad ground connection can also do it.
Also noticed that pin 11 on vga connector is grounded. This don`t happens at the old boards. Could this affect the monitor performance..???
I can either not see that my connections should be wrong.??
Just like this:
VGA PROP
1----240R----23 'forms R signal
1----510R----22 'forms R signal
2----240R----21 'forms G signal
2----510R----20 'forms G signal
3----240R----19 'forms B signal
3----510R----18 'forms B signal
13--240R----17 'H-sync
14--240R----16 'V-sync
At all, 8 wires. See the picture from Moskog. Is this as simple that I`ve done something wrong here???
I`ve also tried interchange H and V wires, but then the monitor did`nt start at all. I put them back again.
If the regulator isn't overheating, not sure what else could do it...
Think I'd try 5 or 3.3 V on Pin 9 again...
If you have a scope, it might help to look at the sync signals and make sure they are there...
You could just look at the DC level with a multimeter too, that might tell you something if it changes when the screen goes black...
Guess you mean ground between the PPB and the main PCB, yes, the grounding is taken good care of.
I tried an LC monitor tonight to see if there were any difference from the Dell, but with same result.
As LA6WNA now has tried the third Propeller Project Board and with plain VGA demo and with nothing else connected and still face the problem I think there is nothing more for us to do.
Nothing else then await for the Tech Support Team to arrive.
Are all cut-to-black events related to something like a Load switching ?
Does it usually always start ok from a cold start ?
If the system is largely stable, and only rarely goes out to lunch, you need to focus on 'how rarely' ?
If you have a Multimeter with Frequency Counter mode, leave that connected to the H sync, or better still, a scope.
I'd try load nothing but a VGA test pattern into a board, and see what your longest Up Time is ?
I have good news! “Propeller Project Board REV B” has a fix for this issue. I’d be more than happy to send you a REV B once they arrive next week. Just send me an email (kcook@parallax.com) with your information and I’ll be sure you get the REV B at no cost.
We discovered a trace issue that made one of the Propeller decoupling capacitors to be ineffective and therefore, on higher definition and some standard VGA video, the reliability was not there. If you were to look at the Cogs running the VGA signals you would see an “out of phase” effect due to this issue.
You should be able to run some simple VGA with the current board. I’m very sorry about the problem!
-Kevin Cook
Thanks a lot, Kevin. Now I can stop spending my time banging my head in the wall...
I`ve scoped the sync pulses tonight, and it seems like the V-sync is getting crazy when the phenomen arrives. I also tried connect an other VGA connector with 470 and 240 ohm resistors and no pull-downs, just like the old boards, but negative results...
So, when your post arrived here I tought; YIPPI.....
We`re really grateful for your support. I`ll send you an email directly tomorrow. Its midnight here, so I guess I go seeing into my head for a while.
Again: THANK YOU ALL FOR NICE REPLIES AND SUPPORT.
Is there a user-patch solution to this problem ?
Excellent work, excellent forum and excellent company!
The crystals' "XI" (input) runs down along the board to the XI on the Quickstart Header. Well this run was inducing some interference on some of the IO.
The "fix" for any existing REV B users is to cut the XI trace that runs down from the crystal. The only way to do this is to drill a hole, since that trace is on an internal layer of the board. See my attached photos for details.
As always, we will replace any Project boards with the upcoming REV C. The update will re-route that trace.
Note, this problem on effects high resolution drivers.