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What is wrong with this schematic for mcp23016-I/SP ? — Parallax Forums

What is wrong with this schematic for mcp23016-I/SP ?

trendtrend Posts: 112
edited 2004-11-29 21:20 in BASIC Stamp
I had someone develop a schematic for me a wile back.. and well.. i am not going to start..

But, basically I have the board cut, and it doesn't work.

I know my bs2p24 works fine .. and· the only thing the picture below doens't show is the resistors (10k ohm) on the sda/scl line...


I believe my code is right, and I am addressing the mcp currectly.

I just think the schematic is wrong.

I can apply 5volts to the input pins on the uln2803a chip and I will get 12v output from the output side of the uln2803a.

I have 2x of the type setup (so I doubt that I have 2 bad mcp chips).

anyways, does anyone know why this schematic isn't working?

Oh yeah.. and as jumpers"" i am using a 10k resistor


Post Edited (trend) : 11/29/2004 9:20:12 PM GMT

Comments

  • trendtrend Posts: 112
    edited 2004-11-29 04:03
    Here is a picture of the actual board... The black rectangles are 1 inch pins (in series of ~8 i think)

    Post Edited (trend) : 11/29/2004 9:20:40 PM GMT
  • trendtrend Posts: 112
    edited 2004-11-29 04:28
    And here is a shot of the underside.. Which to me, doesn't line up with the schematic Dave gave me when he cut the board.. but maybe I am wrong.

    There are 2 resistors/caps (?)(shown by the red arrows)·Not sure what they are.. I am still new to this hole field.. that is why i had someone make a board for me.






    Post Edited (trend) : 11/29/2004 9:20:58 PM GMT
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-11-29 13:01
    Is your code for the MCP23016 correct (setting the ports to outputs as required, then writing to the output registers)? Also, I noticed that your schematic does not have pull-ups on the SCL or SDA lines. You need them for I2C.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • NewzedNewzed Posts: 2,503
    edited 2004-11-29 14:06
    Jon, I designed the mother board that drives the relay board, which I have never seen.· Pullups for SDA and SCL are on the mother board.

    Sid
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-11-29 14:08
    Then it's probably a code thing -- funny how we human programmers are so quick to look for problems outside our own code....

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • trendtrend Posts: 112
    edited 2004-11-29 21:20
    lol.. Jon you are right!

    I might of just been addressing the mcp wrongly.. because I thought I was using the code you looked over :/

    oh well


    thanks! Lee
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