p10 16*32 led matrix shift resistor data input detailed desire

Discussion in 'Embedded Systems and Microcontrollers' started by embedtechnology, Oct 10, 2016.

  1. embedtechnology

    Thread Starter New Member

    Dec 25, 2015
    Hi! I want to know the data input sequence into 16 shift resistors (1/4 of module) in p10 single coloured led matrix(16*32)
    actually when A and B control line 0,0 then line 1,5,9 and 13 are selected for glow. But data input sequence to shift resistors
    for these lines is not known to me. please help
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  2. Papabravo


    Feb 24, 2006
    How are we supposed to have any idea?
  3. embedtechnology

    Thread Starter New Member

    Dec 25, 2015
    I downloaded a data sheet I attached here but it is not sufficient to me can you inform me
    another one which I can download?
  4. JohnInTX


    Jun 26, 2012
    Looking at the datasheet, such as it is..

    It looks like there are 16 74HC595 8 bit shift registers inside the display, daisy chained to make 128 bits. That is 1/4 of the display. There are 4 groups of 128 LEDs in the display selected by the A and B lines.
    For each 1/4 of the display, you write 128 bits of ON/OFF data to the display shift register input with the Shift Clock and Data lines then strobe the Store Clock to latch the data onto the display. Which 1/4 of the display gets lit is determined by the A and B lines as shown in the datasheet. While that data is being shown you can shift the 128 bits for the next group of LEDs. The LEDs won't change until you select A and B for the next group and strobe the Store Clock again.
    I don't know if the A and B lines get latched with the data or if they act like a direct group select. You can find out by sending the 128 bits of data, latching it with the StoreClock then changing A and B. If the group changes, A and B are direct. If not, they are latched.

    Run it fast enough so that it doesn't flicker.
    That's how it looks to me anyway.

    Pull the datasheet for a 74HC595 / 75HC595? for the clock/data/strobe signal levels and timings.
    Good luck.
    Last edited: Oct 10, 2016
  5. MrCarlos

    Active Member

    Jan 2, 2010
    Hello embedtechnology

    First of all it is said: "Shift Register" and not "Shift Resistor".

    The data sheet you attached to your message #3 mentions that the module described therein is based on the IC 75HC505.

    So you also need to study the data sheets IC 75HC595.

    It should also be studied, I believe, the two techniques mentioned in these data sheets:
    1- Serial to parallel conversion.
    2- Persistence of vision.
    The description of this pair of techniques you can find them at google.com.
  6. John P

    AAC Fanatic!

    Oct 14, 2008
    I think JohnInTX has it right. It's actually pretty simple. They could have made it clear whether the two quadrant-select inputs are latched in any way by the shift register control inputs, but since they say nothing I'd assume that it isn't happening, and you just have to hold the levels on those pins while a given quadrant is displayed. It's interesting to see that this display has a four-way interlace scheme, like an old-fashioned raster-scan display but with four sets of horizontal lines instead of two!

    One thing to note with scanned LED displays, if you don't switch from one line (or in this case, set of lines) to another at exactly the same instant as you put data out for the new line, you're likely to see ghost images. It happens because during the brief time when the selection and the data don't match, you may get LEDs being "on" spuriously, and even that short interval is enough to produce a visible effect.

    What's the processor that will drive this thing? It would be best to choose one that has an SPI port.
  7. embedtechnology

    Thread Starter New Member

    Dec 25, 2015
    Johnintx actually I want to know which shift resister cascading after which because there are no sch.diagram
    for the matrix module. I attached a pdf here where I tried to show data latching sequences(which is after which)
    according to my expectation but I think it may be another type. regards.
    Last edited: Oct 10, 2016