PCFP, NXP Semiconductors Interface – I/O Expanders REMOTE I/O EXPANDER datasheet, inventory, & pricing. The PCFP is a remote 8bit I/O expander for I2C bus with interrupt in 16 pin DIP package. It provides general purpose remote I/O expansion via two wire. Product Index > Integrated Circuits (ICs) > Interface – I/O Expanders > NXP USA Inc. PCFP, Obsolete item. PCFP, NXP USA Inc.

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Essentially, what the code does is using the Wire library.

Leave a Reply Cancel reply Your email address will not be published. I used a 2. Another official NXP Datasheet.

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The long lead is connected to the VCC 5V line and the short lead is connected to the resistor. So, there should be only one pin that’s pulled to ground.

On the PCFP, the 2 pins are:. This will allow the current to flow through the LED connected to P5. Click here for instructions on how to enable JavaScript in your browser. All you have to do is to give then their own address unless you want many chips to do the same thing and use that address to talk to the chip in your code.


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Connect to your 5V or 3. Serial Data Line that is used to carry data between the pcf8754p on the bus. Serial Clock Line that is used pf8574p synchronize all communications on the bus. Pay attention to the LEDs orientation. If the value of the bit for that pin is a 1, then it will be pulled high 5V in this case.

Ideally, you should also put a nF ceramic capacitor between the VDD pin and ground. Currently you have JavaScript disabled. There are different ways of working around that limitation. My goal, here, is to turn on only one LED at the time.

Your email address will not be published. I defined a constant for the chip name: To turn off a LED, we will pull its corresponding pin to high.

I never faced situations where I needed that many pins! In order to post comments, please make sure JavaScript and Cookies are enabled, and reload the page. In the setup function, all it does is initializing the Wire library. This is because the way that I2C works is that the lines are pulled low to communicate and have to be pulled high the reminder of the time.

Adding pins to your Arduino using I2C and a PCFP chip | Francois’ Corner

The message payload is made of 8 bits, one per output pin. This may be different if you use another Arduino board. So, to talk to the chip, I will use 0x20 C language notation for 20 in hexadecimal as the chip address.


If the value of the bit corresponding to a pin is a 0, then that pin will be turned low to ground. Atmel Power Debugger — First impressions. Simply change that constant value is you configured the chip with a different address. If you do like this example, you now have an extra 14 pins to play with 2 X 8 pins – 2 pins on the Arduino for I2C bus.

The I2C bus requires 2 wires, so 2 pins on the Arduino and 2 pins on each device attached to the bus. Then, it tells the PCF chip what is the new state of all his 8 output pins. This is useful if you want to use many PCFP chips, on the same I2C bus, because it will allow you to give each of them a unique addresses. Then, in the loop function, it turns each LED on for milliseconds one at the time. Again, VDD means that pin must to be connected to 3.

As mentionned in the wiring section, the 2 pins have to be pulled high with a pull-up resistor.