9 replies to this topic

[Stefan]

Hi, I al currently playing with some IC's I have, and some I don't have. And there's a problem. I tried to order a (HD)74HC674 DIP24 IC but my supplier can't get her hands on it. Also when I use google I only find datasheets but no store that sells the IC. I really would love to get one, especially since I have the code complete to use it If anyone can give me advice in getting that specific IC's or fun IC's in general, it would be appreciated!

[Mario Vernari]

Why not using a couple of HC597 or HC165? Cheers

[Stefan]

1. to save pins 2. because it's just to experiment with 16-bit shift registers

[Mario Vernari]

A 24-pin DIP takes a similar space than two 16-pin DIPs. Remember that is 1.5x longer and 3x larger than the 16-pin DIP. You may connect as many 8-bit shift registers as you want: it is pipeline. Without any additional wire to/from Netduino: the SPI and one Enable line is enough also for 1000-bits! I'd consider a pretty common IC that you may find anywhere for an Euro or less. Cheers

[Stefan]

Well, the actual size doesn't matter, but if I connect two 8-bit shifters, I need to reserve two SS-pins on the netduino, besides the MOSI, MISO and SCLK-pins. So with 1 16-bit shifter it'll take 4 pins and with two 8-bit shifters it takes 5 pins.

[Mario Vernari]

No, no...let's take the HC165.
http://www.nxp.com/d...74HC_HCT165.pdf
Just connect the Q7 (serial out) of the first chip to the DS (serial in) to the second chip. The second chip will be connected as usual to the N.
Also, just tie together the clocks, thus the PL's (=SS).
The problem is that the serial out is *NOT* three-state, so you cannot connect other devices on the same MISO, due collision. If that's not a probelm, your job is done.
Cheers

[Stefan]

hmm have to try that tonight then... now I understand what the Q7' pin does

[Stefan]

Thanks again, Mario! I succeeded to bind 3 74HC595's in serie to control 24 leds. yay Only downside is that I have some big modifications to do to my code. I suppose it starts with Ctrl+A and then Del.

[Jarrod Sinclair]

Thanks again, Mario!

I succeeded to bind 3 74HC595's in serie to control 24 leds. yay

Only downside is that I have some big modifications to do to my code. I suppose it starts with Ctrl+A and then Del.

Just comment it out with a note as to why until your done writing your code. you may end up reusing parts of it later or at least you'll have a record of what you tried.

[Stefan]

Ah well, it's almost done. This is what I have working right now:

Ic74HC595 IcOut1 = new Ic74HC595(SPI_Devices.SPI1, Pins.GPIO_PIN_D10);
Ic74HC595 IcOut2 = IcOut1.LinkedSlave();
Ic74HC595 IcOut3 = IcOut2.LinkedSlave();

// Observant readers will notice the pins are prefixed GPO instead of GPIO.
// This is because the pins can only function as output pin.
OutputPortShift[] pin = {
    new OutputPortShift(IcOut1, Ic74HC595.Pins.GPO_PIN_D0, false),
    new OutputPortShift(IcOut1, Ic74HC595.Pins.GPO_PIN_D1, false),
    new OutputPortShift(IcOut1, Ic74HC595.Pins.GPO_PIN_D2, false),
    new OutputPortShift(IcOut1, Ic74HC595.Pins.GPO_PIN_D3, false),
    new OutputPortShift(IcOut1, Ic74HC595.Pins.GPO_PIN_D4, false),
    new OutputPortShift(IcOut1, Ic74HC595.Pins.GPO_PIN_D5, false),
    new OutputPortShift(IcOut1, Ic74HC595.Pins.GPO_PIN_D6, false),
    new OutputPortShift(IcOut1, Ic74HC595.Pins.GPO_PIN_D7, false),
                
    new OutputPortShift(IcOut2, Ic74HC595.Pins.GPO_PIN_D0, false),
    new OutputPortShift(IcOut2, Ic74HC595.Pins.GPO_PIN_D1, false),
    new OutputPortShift(IcOut2, Ic74HC595.Pins.GPO_PIN_D2, false),
    new OutputPortShift(IcOut2, Ic74HC595.Pins.GPO_PIN_D3, false),
    new OutputPortShift(IcOut2, Ic74HC595.Pins.GPO_PIN_D4, false),
    new OutputPortShift(IcOut2, Ic74HC595.Pins.GPO_PIN_D5, false),
    new OutputPortShift(IcOut2, Ic74HC595.Pins.GPO_PIN_D6, false),
    new OutputPortShift(IcOut2, Ic74HC595.Pins.GPO_PIN_D7, false),
                
    new OutputPortShift(IcOut3, Ic74HC595.Pins.GPO_PIN_D0, false),
    new OutputPortShift(IcOut3, Ic74HC595.Pins.GPO_PIN_D1, false),
    new OutputPortShift(IcOut3, Ic74HC595.Pins.GPO_PIN_D2, false),
    new OutputPortShift(IcOut3, Ic74HC595.Pins.GPO_PIN_D3, false),
    new OutputPortShift(IcOut3, Ic74HC595.Pins.GPO_PIN_D4, false),
    new OutputPortShift(IcOut3, Ic74HC595.Pins.GPO_PIN_D5, false),
    new OutputPortShift(IcOut3, Ic74HC595.Pins.GPO_PIN_D6, false),
    new OutputPortShift(IcOut3, Ic74HC595.Pins.GPO_PIN_D7, false)
};
 
while (true)
{
    // Loops all leds to the right
    for (var OutputPortCount = 0; OutputPortCount < pin.Length; ++OutputPortCount)
    {
        pin[OutputPortCount].Write(true);
        Thread.Sleep(50);
        pin[OutputPortCount].Write(false);
    }
    // Loops all leds back to the left
    for (var OutputPortCount = pin.Length - 2; OutputPortCount > 0; --OutputPortCount)
    {
        pin[OutputPortCount].Write(true);
        Thread.Sleep(50);
        pin[OutputPortCount].Write(false);
    }
}