Arduino Tutorial #3 - Shift Registers (74HC595)

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In the third Arduino Tutorial I discuss one of the many ways that you can expand your outputs on the Arduino. In this case, by using a shift register, I am able to use three Arduino pins to control 8 LEDs.

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[wobblebot]

Am I the only one that got really bothered for a really long time when he wrote (STCP_pin_HIGH)

[Enigma]

12:00 with 180 ohm current limiting resistors on the LEDs, you are pulling around 28mA per output which far exceeds the maximum chip current allotment for the 74HC595 which is 70mA according to the datasheet.

[khawthongxiang]

the STCP_pin and SHCP_pin in the code has to be reversed in order to make it work, but overall its a nice tutorial !

[stevenvanhulle]

Declaring your I/O pins as int is a bad habit. You're declaring them as variables, which they aren't, but as variables they consume RAM. It's better to write

#define STCP_pin 9

[Park]

Hey I think you messed up SHCP and STCP. maybe your cables are switched.
but you have to pull storage LOW outside the loop and the clock LOW and HIGH inside the loop for every bit. 

[iconbylvergara]

There's something wrong with your code in the video. You switched the SHCP_pin to STCP_pin in the writereg() function. And in the second for loop in the void loop sub, you wrote i++ instead of i--

[SatyajitRoy]

Your code is buggy. Array is a zero based index and that's why your LED0 was not turning off. Moreover, you have written at location beyond the allocated memory space for the register array.

[alexdempster]

only 5 of my LED's are working all at different brightnesses. Also they are not oscillating? could you give me any advice as to why. Thanks

[beastbomber]

my shift register almost set on fire -_- do not run the code befor the the vid is finished

[siusiutoe]

i>0  is wrong      i never goes to 0 this way

[anonymousreally]

Cool. But have a question.

when I saw this and before I got to the fritz in schematic I was wondering where will the power come from to light the LEDs. I didn't thing a single pin could provide enough power to run 8 LEDs at once. Using a 2.2v forward voltage avg for LEDs that's 16+volts of drop.

[TizzyT]

I have wondered what working with an arduino was like and your videos have shown me that is actually quite simple (programming wise) I am probably going to have to learn more about the different ICs etc though but thanks a lot.

[transformerkv]

the wrong is in last line . for(int i = 8; i>0; i--) not i++

[kitcat]

Thank you. My own teacher explained this poorly. As a beginner I want to know exactly what is happening. You're a life saver.

[narayans]

can you pls make a vid on ULN2803... great vid

[pjnx]

Thanks for the detailed video.

I'd like to point out a couple of mistakes in it so that you can notify your viewers, the second for in the loop method has a ++ iterator when i think it was meant to be -- since you're iterating down from 8 to 0.

Another problem is that the resistors on the graphical diagram you drew do not match your actual setup, by this i mean that in the diagram the resistors were placed between the output and the + of the leds while in the actual setup you have the resistors between the - of the led and grnd.

[Metralon]

In the schematic the resistors are in between the chip and the (+) side of the LED. But in the actual circuit the resistors sit in between the ground and (-) side of the LED.

[christophergomez]

the first three LEDs connected to Q0 Q1 and Q2 are not lighting up for me even though everything is connected as in the diagram, can anyone explain why?

[SamReidland]

Nice tutorial. Your schematic shows the resisters on the anode, but your implementation has it on the cathode

[BenMDepew]

is the 74HC595 the same as the 74HC595N. Im a noob in ICs.