74HCTN datasheet, 74HCTN pdf, 74HCTN data sheet, datasheet, data sheet, pdf, NXP Semiconductors, 8-bit serial-in, serial or parallel-out shift. 74HCTN datasheet, 74HCTN circuit, 74HCTN data sheet: PHILIPS – 8-bit serial-in/serial or parallel-out shift register with output latches; 3-state. 74HCTN datasheet, 74HCTN circuit, 74HCTN data sheet: NXP – 8-bit serial-in, serial or parallel-out shift register with output latches; 3-state.

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At sometime or another you may run out of pins on your Arduino board and need to extend it with shift registers.

This example is based on the 74HC The datasheet refers 47hct595n the 74HC as an “8-bit serial-in, serial or parallel-out shift register with output latches; 3-state.

You can link multiple registers together to extend your output even more. Users may also wish to search for other driver chips with “” or “” in their part numbers, there are many.

How this all works is through something called “synchronous serial communication,” i. It’s by pulsing second pin, the clock pin, that you delineate between bits.

This is in contrast to using the “asynchronous serial communication” of the Serial. Once the whole byte is transmitted to the register the HIGH or LOW messages held in each bit get parceled out to each of the individual output pins.

This is the “parallel output” part, having all the pins do what you want them to do all at once. The “serial output” part of this component comes from its extra pin which can pass the serial information received from the microcontroller out again unchanged.

This means you can transmit 16 bits in a row 2 bytes and the first 8 will flow through the first register into the second register and be expressed there. You can learn to do that from the second example. You can only set the whole chip together.

This is a pretty specialized thing to do — Think of an LED array that might need to be controlled by completely different microcontrollers depending on a specific mode setting built into your project. Neither 74ht595n takes advantage of this feature and you won”t usually need to worry about getting a chip that has it.


Here is a table explaining the pin-outs adapted from the Phillip’s datasheet. This set up makes all of the output pins active and addressable all the time.

The one flaw of this set up is that you end up with the lights turning on to their last state or something arbitrary every time you first power up the circuit datasueet the program starts to run. You can get around this by controlling the MR and OE pins from your Arduino board too, but this way will work and leave you with more open pins. From now on those will be refered to as the dataPin, the clockPin and the latchPin respectively.

In this case you should connect the cathode short pin of each LED to a common ground, and the anode long pin of each LED to its respective shift register output pin. Using the shift register to supply power like this is called sourcing current. Some shift registers can’t source current, they can only do what is called sinking current. If you have one of those it means you will have to flip the direction of the LEDsputting the anodes directly to power and the cathodes ground pins to the shift register outputs.

You should check the your specific datasheet if you aren’t using a series chip.

74HCT595N Datasheet

Datasheer forget to add a ohm resistor in series to protect the LEDs from being overloaded. Here are three code examples. The first is just some “hello world” code that simply outputs a byte value from 0 to The second program lights one LED at a time. The third cycles through an array. The code is based on two pieces of information in the datasheet: The logic table is what tells you that basically everything important happens on an up beat.

Tutorial: Arduino Motor/Stepper/Servo Shield – Part 3: 74HCT595 Shift Register

When the clockPin goes from low to high, the shift register reads the state of the data pin. As the data gets shifted in it is saved in an internal memory register. When the latchPin goes from low to high the sent data gets moved from the shift registers aforementioned memory register into the output pins, lighting the LEDs.

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In this example you’ll add a second shift register, doubling the number of output pins you have while still using the same number of pins from the Arduino.

Starting from the previous example, you should put a second shift register on the board.

74HCTN Datasheet(PDF) – NXP Semiconductors

It should have the same leads to power and ground. Two of these connections simply extend the same clock and latch signal from the Arduino to the second shift register yellow and green wires. The blue wire is going from the serial out pin pin 9 of the first shift register to the serial data input pin 14 of the second register. In this case I added green ones so when reading the code it is clear which byte is going to 74hct59n set of LEDs.

Here again are three code samples. If you are curious, you might want to try the samples from the first example with this circuit set up just to see what happens. It sends out a second byte. This forces the first shift register, the one directly attached to the Arduino, to pass the first byte sent through to the second register, lighting the green LEDs.

The second byte will then show up on the red LEDs. Here they need to be moved back into the main loop to accommodate needing to run each subfunction twice in a row, once for the green LEDs and once for the red ones. This means that line.