1

im using arduino and im out of pins.

I need something like a decoder but the problem is that the decoders only change one output pin I.E. for 0011 the output will be 0001000000000000 what i need is to have the first outputs on I.E for 1000 the output will be 111111111000000000 i basically need to light up to 16leds and im out of pins so i was wondering is there is any IC that does this for me if i have 1111 it will output 16 ones.

6

You can use one (or more, daisy-chained) shift register for that.

It will normally take you 3 pins and provide 8 outputs, or 8n where n is the number of chained shift registers still using only 3 Arduino pins.

One example of a shift register that fits your situation is the 74HC595.

On Arduino, you can use shiftOut function to help handle those ICs.

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2

You could use the MCP23017 an i2c 16 input/output port expander. (datasheet)

It allows you to control 16 I/O pins via a simple I2C interface (only 2 pins needed). And an Arduino library exists for it.

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