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uVGA-II won't respond from power-up...

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  • uVGA-II won't respond from power-up...

    Hi all.


    I am trying to get the unit working with a PICAXE controller.

    Here is the test code:


    #no_data

    setfreq m8 'Set 8MHz speed

    high C.0 'pin high for TTL comms

    pause 1200 'Allow uVGA to startup(must be at least 500ms)
    serout C.0,T9600_8,("U") 'Autobaud command. MUST be first command sent, MUST be 9600 baud.
    serin B.1,T9600_8,b1 'Wait for ack from uVGA
    pulsout B.1,10000 ' Pulse LED

    start:
    serout C.0,T9600_8,("E") 'Clear the screen
    serin B.5,T9600_8,b1 'Listen for response from uVGA - don't care what byte it is
    pulsout b.1,10000 'Pulse LED
    serout C.0,T9600_8,("V") 'Request version information on screen
    serin B.5,T9600_8,b1 'Listen for response
    pulsout b.1,10000 'Pulse LED
    wait 8 '4 second delay
    goto start


    Nothing fancy - just issues the autobaud character, then clears the screen, then shows the version info.

    I am not getting anything - not even the first ack byte back once sending the U command at the very start.

    I don't think I have done anything wrong with the test code.

    I don't have pullups on TXD and RXD, but I did put them in for the purposes of testing, and that did not help at all, so I removed them again. Should TXD and RXD have 4k7 pullups or so?

    I connected up a serial LCD module to the output of the PICAXE chip, and it most certainly is sending a U character about 600ms after power up, but the uVGA seems to be ignoring it.

    Does anyone have any hints of things I could try?

  • #2


    What does the uVGA display on the attached monitor?

    Have you got TX on the Picaxe connectred to RX on the uVGA and viceversa?
    Mark

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    • #3


      Hello.


      Thank you for the reply.

      uVGA performs the normal starup - as though it has not received the U character.

      The PICAXE output pin(port C.0) is connected to pin-3(RX) of the uVGA, and PICAXE input pin(port B.5) is connected to pin-2(TX) of the uVGA. RESET pin is left floating on the uVGA - not connected to anything, not even a wire attached to that pin.

      With power applied, the screen is blank for about 5 seconds, then it shows the 4D splash-screen.

      With my serial LCD terminal thing attached(and set to 9600 baud), what happens is that about 750ms from power-up, a U appears on the LCD, then followed by an E, a 250ms pause, then a V. The E and V sequence loops, the U is only sent once at power-up.

      Hope that helps a little.

      Comment


      • #4


        Try increasing pause so that the Autobaud is not sent until after the splash appears.

        If that works then try decreasing it a bit at a time
        Mark

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