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PCF8574 Port Expander LEDs, Keypad & Buzzer Module, suits Arduino and Pi

PCF8574 Port Expander LEDs, Keypad & Buzzer Module, suits Arduino and Pi


Full self-assembly kit for Arduino and Pi projects.


Other standard PCF8574 PCB modules have just the chip and a connector. You have to yourself externally wire pushbuttons, LEDs, buzzer and drive transistor if you want it to do anything useful. But this great kit makes all that massively easier.....

  • Product Info

    This really useful kit easily allows you to add up to 8 LEDs with optionally up to 8 pushbuttons, plus a buzzer and relay driver, with no other external components needed.


    The PCF8574 has 8 I/O, and the 8 LEDs share their PCF8574 pins with 8 pushbuttons. You can choose to either fit LEDs if you just want LED outputs, or you can fit buttons if you just want pushbutton inputs. You can also choose to fit the LEDs along with the buttons - in this case the LEDs can be driven on or off by the PCF8574, and when you press a button, the LED always goes on.


    The 8th LED is also connected to a drive transistor - so can energise the on-board buzzer and/or switch an external relay via the on-board connector.


    When ordering, please choose what LED colours you would like. If you don't see the mix that you need, please send a message and we'll make it for you.


    Available with two different types of LEDs that you can choose from when ordering:

    • Clear: these LEDs are super bright when viewed from the front, but are a little dimmer when viewed from the side.
    • Diffused: these LEDs are not quite as bright as the Clear, but they do give a better all-around viewing.


    The PCF8574 uses standard available Arduino software libraries and communicates over I2C bus. You can set the PCF8574 I2C address (using the 3 jumpers supplied) to any of 8 addresses. This lets you have up to 8 PCF8574 devices on a single I2C bus. There are input and output connectors at the sides of the PCB for easy daisy-chaining of multiple devices.


    The kit comes with the PCB, all components, full instructions, PCB layout diagram, schematic diagram, and examples of Arduino software to drive the LEDs and read the buttons.


    The PCB measures just 79mm x 30mm, with 4 handy fixing holes. You can stack several of these modules side by side to make long displays and keypads.


    Please note that the kit:
     - requires good soldering skills.
     - contains flashing lights.
     - is not suitable for small children due to small parts.
     - must be used only for the purposes of fun and amusement.
     - is for occasional indoor domestic UK home use.
     - must not be used near sensitive electronic or medical equipment.
     - is for hobbyist construction and enjoyment.
     - must not be exported outside of the UK.
     - is not for resale in unassembled or any assembled form.

    Prepared at an antistatic workstation, supplied in an ESD protective bag, dispatched in a padded jiffy bag.


    This kit was fully designed by the shop owner, and has full technical support.

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