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VGA problem — Parallax Forums

VGA problem

Areal PersonAreal Person Posts: 197
edited 2006-12-29 15:29 in Propeller 1
·
Ok, I’m new to this stuff and I don’t know what I’m doing wrong.
·
I’ve hooked up a VGA cable according to the demo board diagram
on my very simple breadboard setup. I’ve double checked the pin outs on the
VGA db15 connector for connectivity and they all check ok, I know the monitor works
It’s a standard 15inch Compaq brand, I know pins p16-p23 are working, (I can flash LED’s on each pin).
·
But when I try to run VGA_TEXT_DEMO.spin, nothing happens, no VIDEO.
I had this working about 3 weeks ago on a different breadboard setup, I’m using
the same VGA cable I used then.
·
It may be a simple stupid problem, or whatever.
·
Is pin9 required to be on 5 volts ?
·
Also, I just plugging each VGA pin to the correct Propeller Pin
i.e –
·
VGA p16 – p23 with the resistor in the middle.
VGA p5,p6,p7,p8 & p10 go to the 3.3v ground
·
Do I need to ground each of the prop pins p16-p23 ?
·
This is ridiculous, I simply don’t know what else to check.
·
Thanks,
-Areal

Comments

  • Bill HenningBill Henning Posts: 6,445
    edited 2006-12-06 17:53
    Here's what I suggest; this is what let me solve my problem with video output [noparse]:)[/noparse]

    1- using an ohm meter, check that the resistance is correct from each pin of the propeller socket to the vga connector pin to make sure it is correct
    2- write a little program to turn on/off each of the outputs on the propeller, and measure the voltages at the output of the connector with a 75ohm load between the pin (r,g,b,vsync,hsync, one at a time) and ground to make sure you are getting a signal in the 0v-1v range

    My problem turned out to be a bad RCA connector!

    Best,

    Bill
  • Areal PersonAreal Person Posts: 197
    edited 2006-12-06 19:02
    Ok, I did step #1 I checked the resistance for p16 - p28 as you said, from the pin socket to the VGA connector.
    everything shows correct.

    p16 - 239ohm
    p17 - 238ohm
    p18 - 472ohm
    p19 - 246ohm
    p20 - 463ohm
    p21 - 239ohm
    p22 - 465ohm
    p23 - 239ohm

    OK, I did step #2, all the pins (p16-p23) through to the VGA show .8v - 2.0v when I toggle the pins,
    with a line of spin code, I also used the 75ohm as you said in the middle.

    I also rechecked the grounds, I don't know why this is not working.

    What else can I check ?

    -Areal
  • Areal PersonAreal Person Posts: 197
    edited 2006-12-06 21:46
    Ok, I've still not been able to get this to work.

    Do I need the +5v ? I have not hooked that up.

    I also made a second connector setup, and it also will not work.
    I don't have a scope.

    Can someone explane how to test the pins to make sure the chip has not been damaged
    in any way ? I have a volt meter, can I use that to verify the chip ? How do I do it ?

    I again have double checked the ohms & voltages, and also the grounds comming out of the
    VGA female connector, and the monitor DOES work if I hook it up to a computer.

    Is this not a simple thing to do ?

    Thanks for all the help,

    Post Edited (Areal Person) : 12/6/2006 9:58:41 PM GMT
  • NewzedNewzed Posts: 2,503
    edited 2006-12-06 21:57
    Can you post the instruction that starts your VGA, something like:

    vga.start(16.........

    Sid

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Sid Weaver
    Don't have VGA?

    Newzed@aol.com
    ·
  • Areal PersonAreal Person Posts: 197
    edited 2006-12-06 21:58
    I'm using the VGA_TEXT_DEOM.SPIN program
    ....................................................................

    CON

    _clkmode = xtal1 + pll16x
    _xinfreq = 5_000_000


    OBJ

    text : "vga_text"


    PUB start | i

    'start term
    text.start(16)
    text.str(string(13," VGA Text Demo...",13,13,$C,5," OBJ and VAR require only 2.6KB ",$C,1))
    repeat 14
    text.out(" ")
    repeat i from $0E to $FF
    text.out(i)
    text.str(string($C,6," Uses internal ROM font ",$C,2))
    repeat
    text.str(string($A,12,$B,14))
    text.hex(i++, 8)
  • NewzedNewzed Posts: 2,503
    edited 2006-12-06 23:10
    On the board connector that the VGA cable pugs into - are pins
    6-7-8-9-10 grounded?

    Sid

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Sid Weaver
    Don't have VGA?

    Newzed@aol.com
    ·
  • Areal PersonAreal Person Posts: 197
    edited 2006-12-07 00:14
    Yes, they are.

    I thought pin 9 was +5v ?

    I had not hooked that one up before.

    But I did hook it to ground now , but it still will not work.

    -Areal
  • NewzedNewzed Posts: 2,503
    edited 2006-12-07 00:23
    DB15 Pin 13 should go to Prop Pin 17 and DB15 Pin 14 should go to Prop Pin 16.· Is that what you have?

    Just eliminating possibilities.

    Sid

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Sid Weaver
    Don't have VGA?

    Newzed@aol.com
    ·
  • NewzedNewzed Posts: 2,503
    edited 2006-12-07 00:52
    Areal. looking at the female DB15 connector, Pin 1 is the upper right hand hole.·· Is that the way you are measuring?

    Sid

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Sid Weaver
    Don't have VGA?

    Newzed@aol.com
    ·
  • Areal PersonAreal Person Posts: 197
    edited 2006-12-07 03:14
    @Sid

    Yes, pin 1 is top right.
    Yes, pin vga13 goes to p17 & vga14 go to p16

    I don't know what else to check ?

    I heard that there are two sides to a pin, sync ? and what else ?

    Is it possiable for an LED to flash from a spin program, but
    for the VGA stuff to be damaged in the chip ? is this possiable ?

    How can I check the pins on the chip to verify that it is not damaged in some way ?

    OK< I'm going to the Diode check on the pin alt to Vss or VDD.
    I'm checking the integrity of parasitic diodes from the silicon substrate

    "With the positive probe to VSS the port pins read around 420mv. With the ground probe to VDD the port pins read 630mv. The exact reading doesn't matter too much but you should find them in this general range however all the port pins should read much the same, any significant difference probably indicates a breakdown of the substrate." Per Peter Jakacki's instructions.

    I'll let you know what I find.



    Thanks for the help,
    -Areal

    Post Edited (Areal Person) : 12/7/2006 3:47:26 AM GMT
  • Areal PersonAreal Person Posts: 197
    edited 2006-12-07 03:37
    Ok, all my pins on a diode check show about 478mv on the port side.

    I guess this is ok ?, it's higher that 420mv but there all about the same.

    checking VDD to ground and the port pins are reading just under 630mv around 600mv.

    Ok, I'll start over from scratch a forth time.

    -Areal

    Post Edited (Areal Person) : 12/7/2006 3:41:34 AM GMT
  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-12-07 06:48
    What monitor are you hooking it up to? CRTs will take what you throw at them, LCD monitors are a different story. Good ones will take it, some will complain and others (the really cheap ones) wont do anything. This is because the resolution is not standard for all but a couple of the VGA drivers.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • NewzedNewzed Posts: 2,503
    edited 2006-12-07 12:52
    Areal, if you will post a copy of the program you are actually using, along with the objects you are using, I will run it and eliminate any program problems.· If you prefer, you can send it direct to [url=mailto:Newzed@aol.com.]Newzed@aol.com.[/url]

    Sid

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Sid Weaver
    Don't have VGA?

    Newzed@aol.com
    ·
  • Areal PersonAreal Person Posts: 197
    edited 2006-12-07 19:13
    @Newzed

    I dont understand what your asking for.
    I downloaded the software from this site. It's the propeller tool software bundle

    Here the example I'm using the VGA_TEXT_DEOM.SPIN program
    It was written by Parallax. Its one of the canned example programs.
    ....................................................................

    CON

    _clkmode = xtal1 + pll16x
    _xinfreq = 5_000_000


    OBJ

    text : "vga_text"


    PUB start | i

    'start term
    text.start(16)
    text.str(string(13," VGA Text Demo...",13,13,$C,5," OBJ and VAR require only 2.6KB ",$C,1))
    repeat 14
    text.out(" ")
    repeat i from $0E to $FF
    text.out(i)
    text.str(string($C,6," Uses internal ROM font ",$C,2))
    repeat
    text.str(string($A,12,$B,14))
    text.hex(i++, 8)
  • NewzedNewzed Posts: 2,503
    edited 2006-12-07 19:30
    The reason I asked for the specific code your are running is to make sure nothing got lost or garbled when you downloaded it.· I have the Parallax program so I don't need that.· What I want is what you are running, including the object you are using.

    Sid

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Sid Weaver
    Don't have VGA?

    Newzed@aol.com
    ·
  • Areal PersonAreal Person Posts: 197
    edited 2006-12-07 19:47
    Ok,

    I'm just executing that single program. I installed the software directly from the
    download without modificaytion. My propeller is on a breadboard
    and that's all I'm trying to do is get VGA working, stripped down simple as possiable.

    Here’s how I’m hooking the pins up
    from the propeller chip to the “VGA” monitor

    I simply cannot get the VGA feature to work
    vga-p5 –> VSS
    vga-p4 –> VSS

    resistor groupings
    vga-p3 –> 470ohm –> prop-p18
    vga-p3 -> 240ohm –> prop-p19

    vga-p2-> 470ohm -> prop-p20
    vga-p2-> 240ohm –> prop-p21

    vga-p1->470ohm –> prop-p23
    vga-p1->240ohm –> prop-p24

    vga-p10, p9, p8, p7, p6 -> VSS

    vga-p15 -> VSS
    vga-p14 – 240ohm -> prop-p16

    vga-p13 – 470ohm -> prop-p17
    vga-p13 – 240ohm -> prop-p18

    vga-p12,p11 -> VSS

    It's my understanding that it is really simple to hook up VGA ?

    I'm using the Propeller Demo Board Rev D Schematic (9-18-06)
    for my breadboard setup. The only thing I'm doing different is I'm not applying
    5v to pin 9 (I'm grounding everything that does not go to a propeller pin)

    I also do not have any LED's on the right side (as the demo board does, and has them grounded also),
    I'm just wiring the VGA pin directly to the propeller pin through the correct resistor(s) for that pin.
    and I've never put more that 3.3v through the propeller.

    I have re done this setup 5-6 times, with fresh VGA cable, I used different
    resistors and fresh wiring setup. I used a beadboard and then I soldered a prefboard
    setup. I've tryed a different monitor, switched powersupplies. I checked the pins
    on the propeller, however, I'm not sure if my readings were ok, I posted them above.

    I havent replaced the propeller chip yet, I'm waiting for one to come in
    to swap it out.

    Thanks for all the help,

    The monitor has worked in the past with this setup
    Power supply is good.

    Thanks
    -Areal
  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-12-07 19:50
    Go ahead and connect pin 9 to 5V.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • Areal PersonAreal Person Posts: 197
    edited 2006-12-07 20:17
    Ok, p9 to 5v, nothing

    Could you tell me where the 5v is grounded ?

    I had the dumb thing working at one time in the past.
    I was not using the p9-5v then. I don't know why this
    will not work now. it's not making any sence to me.

    I remember on my breadboard I had all my LED's plashing on p16-p23
    and I removed them and just plugged in my VGA cable I had cut off
    and soldered resistors to, and it just worked so easy without effort [noparse]:([/noparse]

    And now, it's like it some kind of very difficult task.

    -Areal

    Post Edited (Areal Person) : 12/7/2006 8:31:36 PM GMT
  • NewzedNewzed Posts: 2,503
    edited 2006-12-07 20:57
    Areal, you skipped over Pin 22.

    Sid

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Sid Weaver
    Don't have VGA?

    Newzed@aol.com
    ·
  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-12-07 21:41
    Sid is correct, you shifted the two pins up, the VGA's P1 is connected to P22 and P23 of the Propeller you also have a couple other errors, here is the correct mapping (red indicates change, strike-through red means deleted):

    vga-p5 –> VSS
    vga-p4 –> VSS

    resistor groupings
    vga-p3 –> 470ohm –> prop-p18
    vga-p3 -> 240ohm –> prop-p19

    vga-p2-> 470ohm -> prop-p20
    vga-p2-> 240ohm –> prop-p21

    vga-p1->470ohm –> prop-p22
    vga-p1->240ohm –> prop-p23

    vga-p10, p9, p8, p7, p6 -> VSS

    vga-p15 -> VSS
    vga-p14 – 240ohm -> prop-p16

    vga-p13 – 240ohm -> prop-p17
    vga-p13 – 240ohm -> prop-p18

    vga-p12,p11 -> VSS

    Also be sure when you refer to prop-pX, you are using Port X not Pin X of the package.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • Areal PersonAreal Person Posts: 197
    edited 2006-12-07 22:25
    Ok, I did make some type O's in my posting.

    I have specificly rechecked and now have corrected all pinouts to match Pauls instructions.

    Still no luck,

    It's my understanding that each propeller pin itself does not need to go to ground
    as it would if I were flashing LED's . Correct ?

    I've ordered a new propeller chip, just in case. Good for me to have spares also [noparse]:)[/noparse]

    I'm going to try the RCA TV setup tonight at home. (after work)
    and try to get that going. I really need to get past this point so I can move on
    to a new phase.

    P.S. I'm using a standard 15" VGA monitor

    Also, is there anyway to verify the VGA signal out of the VGA connector
    of my setup while I running a spin program that should be displaying
    Text on the monitor, that way maybe I couls find a pin with the wrong/weal/bad signal
    and trace it to a specific pin ? How can I do this ?

    Could I use a scope ?

    Thanks for the help,
    -Areal

    Post Edited (Areal Person) : 12/7/2006 10:31:42 PM GMT
  • Areal PersonAreal Person Posts: 197
    edited 2006-12-08 01:51
    It's got to be a bad chip. I don't see how it could be anything else
    it just two hard to get this to work.

    I've now tried to hook up the RCA TV jack
    and it will not work. I've got 3 resistors
    and the RCA plug grounded to 3.3
    I've got my sony TV on Video 1

    I dont understand why this chip would be bad
    I've not abused any at all.

    [noparse]:([/noparse]
  • Harrison.Harrison. Posts: 484
    edited 2006-12-08 02:39
    Are you sure that your Propeller is running at 80mhz? To test this, I would recommend a short program to blink an led 1 time per second at 80mhz. If you find out the led is blinking slower than 1 time per second then you will know that the Propeller is not running at the correct 80mhz that is default for the video demos / drivers.
  • Areal PersonAreal Person Posts: 197
    edited 2006-12-29 15:29
    OK, I replaced the Propeller chip and it worked, I must have damaged the chip
    somehow through ESD etc.

    It is not a problem with Parallax.

    NOTE: I'm updating this thread because some people have sent me private messages
    ········· asking for the information.



    Thanks everyone,
    -Areal Person

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    I have a tree growing out of my head, but

    what do you expect ? I'm a programmer.
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