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DLP Prop board doesn't work without USB host? — Parallax Forums

DLP Prop board doesn't work without USB host?

Miles from LangleyMiles from Langley Posts: 3
edited 2007-09-25 19:50 in Propeller 1
Among other boards I have a DLP Designs 'DLP Prop' which is a bit like a PropStick. I think I must be doing something wrong because I just can't get it to work without a USB connection to a host. I powered it from a 7805 5V regulator but no luck. Does it do nothing until it has communicated it's USB ID or is it some simple power thing I just don't get? Can it be made to work stand-alone? Perhaps the FTDI USB USART thang can be tweaked? I feel that there must be a document·I haven't found which explains it all.
I could not get a response from the manufacturers and I don't want to waste it so -·if anyone has·succeeded with this I would be grateful for advice.

Miles

Comments

  • Don @ DLPDon @ DLP Posts: 6
    edited 2007-09-25 12:30
    Hi Miles,

    The DLP-Prop was designed to remained connected to a host PC.· The clock for the Propeller is taken from the USB IC which goes to Standby mode when the 1mS frames from the host stop.

    If you want to operate without the host connected then you will have to enable the internal oscillator in the Propeller and apply your own 3.3V power supply to the SW33V pin (pin 17).

    Also, its best to not have your 3.3V supply connected while also connected to the host PC so you are not driving the output of the 3.3V regulator.

    Regards,
    Don
    ·
  • Miles from LangleyMiles from Langley Posts: 3
    edited 2007-09-25 12:49
    Thankyou Don. That must be definitive. I will read up on it when able, but can you tell me how to enable the internal oscillator?

    Rgds

    Miles
  • Don @ DLPDon @ DLP Posts: 6
    edited 2007-09-25 13:22
    I don't claim to be an expert in Spin programming, but it should something like
    _clkmode = RCFAST

    Try this listing:


    '' Propeller "Hello, World!" demo
    '' -- blink an LED on pin A27
    ''
    '' A27>───────┐
    '' 330Ω 

    CON
    _clkmode = RCFAST ' use internal osc

    Led = 27

    VAR
    long delayTime ' used for delay

    PUB BlinkLED

    dira[noparse][[/noparse]Led] := 1 ' make the pin an output

    repeat
    outa[noparse][[/noparse]Led] := !outa[noparse][[/noparse]Led] ' toggle the pin state
    delayTime := cnt + 8_000_000 ' delay = 8 million cycles
    waitcnt(delayTime) ' wait
  • Miles from LangleyMiles from Langley Posts: 3
    edited 2007-09-25 13:33
    Don,
    I hoped it would be something like that. That is very easy.
    I like the DLP Prop now.
    Thankyou again.
    Rgds
    Miles
  • Graham StablerGraham Stabler Posts: 2,507
    edited 2007-09-25 13:33
    Oh dear I didn't realize the need for a permanent host connection (RC oscillator is no use to me), if anyone wants a half priced DLP-prop let me know.

    Graham
  • hippyhippy Posts: 1,981
    edited 2007-09-25 14:32
    Don @ DLP said...
    The DLP-Prop was designed to remained connected to a host PC. The clock for the Propeller is taken from the USB IC which goes to Standby mode when the 1mS frames from the host stop.
    I think that should be made much clearer and explicit in the datasheet. While it says the Propeller is driven by an external 6MHz clock derived from the USB interface, it makes no mention that this clock stops if USB is disconnected.

    I'm very glad I did not buy a DLP-Prop as it would not have delivered what I expected.
    Graham Stabler said...
    Oh dear I didn't realize the need for a permanent host connection (RC oscillator is no use to me).

    Maybe some circuit surgery is in order to take the XIN to an external leg and drive that from an external oscillator module ?
  • ColeyColey Posts: 1,110
    edited 2007-09-25 16:25
    Don @ DLP said...
    The clock for the Propeller is taken from the USB IC which goes to Standby mode when the 1mS frames from the host stop.

    Don, I've had several issues with the DLP Prop but the main one was that the clock out of the FTDI chip is ~6MHz and fluctuates all over the place.
    Is this norma?l It makes the device useless for video work!

    Or do I just have a faulty device?

    Regards,

    Coley
  • Graham StablerGraham Stabler Posts: 2,507
    edited 2007-09-25 16:42
    Coley, that's the reason I didn't find out about this issue, the clock put me off using it.

    Graham
  • crgwbrcrgwbr Posts: 614
    edited 2007-09-25 16:54
    Don't know if this will help anyone, but I ended up disabling the clock from the ft232r using Mprog and soldering a 5mhz crystal onto the XO and XI pins. Tricky to soldering, but it worked great.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "... one of the main causes of the fall of the Roman Empire was that, lacking zero, they had no way to indicate successful termination of their C programs." -

    "If Python is executable pseudocode, then perl is executable line noise."

    "The best accelerator available for a Mac is one that causes it to go at 9.81 m/s2."

    "My software never has bugs. It just develops random features."

    "Windows isn't a virus, viruses do something."

    "Programmers are tools for converting caffeine into code."

    "Enter any 11-digit prime number to continue."
  • ColeyColey Posts: 1,110
    edited 2007-09-25 19:50
    Good idea that crgwbr, I will dust my DLP Prop off and give it a try....
    I must admit I'd given up all hope on it lol

    Regards,

    Coley
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