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Decoder for 128 outputs

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mkrtich.nazaryan

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Hi all,
I need to control 72 LEDs independently. I see this way: use some micro-controller for example PIC18X, and because 18X have 3 output register A,B,C (some of 18X series has 4 register), so I need decoder from 3*8 inputs to 72 output, and because 72 is not of multiple of 2, I think I need to use 128. So I need decoder or decoders to get 128 outputs and controlled by 18 inputs. Programmable I will switch the LED or LEDs over thank 100Hz frequency, and in this case the LED or LEDs will looks like switched on.
Let me know If you have other ideas to realize this.
Thanks.
 

You can use DS2408, you need 16 pieces of them, all over 1-wire.

Each DS2408 have unique address and can control individualy 8 switches, also can sense switches.
You can control with that other devices and equipment with more power.

You can always easily extend your need for more led or something else.

Also on 1-Wire you can simply attach digital potentiometer and dimm your led (exampleDS2890), all over just two wires on long distance.

Each LED can be controlled, and all works over two wires. Can use control combination PC / uC.


Example :
 

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I've used the Microchip Port Expanders in numerous designs.

They make great keypad interfaces and they also offer very handy interrupt features as well.

You can cascaded several on a single I2C or SPI interface, freeing up the microcontroller I/O for other tasks.

For a simple output only task a shift register like the 74HC595 would easily fulfill your requirements:

Introduction to 74HC595 shift register – Controlling 16 LEDs

BigDog
 

maxim also has 16 channels decoder via spi ...
**broken link removed**
 
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    tpetar

    tpetar

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Or use a MAX7219 or it's sucessors, it will drive 64 independent LEDs in a matrix and do the multiplexing for you. It can be expanded by chaining more devices. With 2 of these devices and four control lines you can turn any or all of 128 LEDs on or off.

Brian.
 

alexan_e said:
Did you check the price $20.54 @1k ?
Click to expand...

MAXIM manufactures nice products, but they are rarely inexpensive.

A similar device from Microchip, MCP23S17, is only $0.92 @ 1K, $1.26 for singles. That's getting close to shift register pricing.

BigDog

---------- Post added at 10:50 ---------- Previous post was at 10:47 ----------

@tpetar

I actually used the DS5000 series in several designs over a decade ago. If you think their expensive now, you should have seen the pricing then.
 

I actually used the DS5000 series in several designs over a decade ago. If you think their expensive now, you should have seen the pricing then.
Click to expand...

I just checked still 70usd piece for DS5000T. They stuck prices, probably because production costs.
**broken link removed**

Just DS5000 without RTC is 63usd. :sad:
 
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