Forum Update - Announcement about May 10th, 2018 update and your password.

graphics demo pin connection

I'm trying to use the graphics demo. I'm using the professional development board that has 4 resistors going to an rca jack. "Tv" is a child object under the graphics demo, I found the pinout for the jack in the dat section, but i'm not having any luck with the display. How to use the demo is not clear to me, am I missing something? Also I do have the tv set to video 1, which is the jack i'm connected to.
pin3-560
pin2-270
pin1-560
pin0-1.1k

  the broadcast signal nibble is arranged as:
''        bit 3: aural subcarrier (sum 560-ohm resistor into network below)
''        bits 2..0: visual carrier (sum 270/560/1100-ohm resistors to form 75-ohm 1V signal)
''  _______

Comments

  • 3 Comments sorted by Date Added Votes
  • Problem solved, i was looking at boards at the parallax site and on the silkscreen of one it said tv pin 12..15. Tried it with graphics demo and it works.
  • Just for future reference I'm including an answer Ariba posted to a very similar question I had a month ago.
    Ariba wrote: »
    You find the description of the pin settings in the TV.spin object:
    ''  tv_pins
    ''
    ''    bits 6..4 select pin group:
    ''      %000: pins 7..0
    ''      %001: pins 15..8
    ''      %010: pins 23..16
    ''      %011: pins 31..24
    ''      %100: pins 39..32
    ''      %101: pins 47..40
    ''      %110: pins 55..48
    ''      %111: pins 63..56
    ''
    ''    bits 3..0 select pin group mode:
    ''      %0000: %0000_0111    -                    baseband
    ''      %0001: %0000_0111    -                    broadcast
    ''      %0010: %0000_1111    -                    baseband + chroma
    ''      %0011: %0000_1111    -                    broadcast + aural
    ''      %0100: %0111_0000    broadcast            -
    ''      %0101: %0111_0000    baseband             -
    ''      %0110: %1111_0000    broadcast + aural    -
    ''      %0111: %1111_0000    baseband + chroma    -
    ''      %1000: %0111_0111    broadcast            baseband
    ''      %1001: %0111_0111    baseband             broadcast
    ''      %1010: %0111_1111    broadcast            baseband + chroma
    ''      %1011: %0111_1111    baseband             broadcast + aural
    ''      %1100: %1111_0111    broadcast + aural    baseband
    ''      %1101: %1111_0111    baseband + chroma    broadcast
    ''      %1110: %1111_1111    broadcast + aural    baseband + chroma
    ''      %1111: %1111_1111    baseband + chroma    broadcast + aural
    ''      -----------------------------------------------------------
    ''            active pins    top nibble           bottom nibble
    
    and yes, it's a bit complicated.
    Simplified:
    Set the pin group in the upper nibble and the lower nibble to %0000 if you use the lower 4 pins of the pingroup, or %0101 if you use the upper 4 pins of the group.

    A possible calculation from the pin number (untested):
      tvparams[2] := pin>>3 << 4 | (pin>>2 & 1) * %0101
    

    Andy
  • Thanks Andy
Sign In or Register to comment.