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Author: cstanton
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Raspberry Pi 4 Model B Default GPIO Pinout with PoE Header

 

 

Click the image for an enlarged version:

 

 

Here is the Raspberry Pi 4 default GPIO pinout for the 40 pin J8 header. This is the configuration of the pins as you'll receive it when you first boot up Raspbian, or NOOBS with Raspbian. However, did you know that they are configurable? Yes, you can change the allocation of the Serial Peripheral Interface BUS on the pins, or decide that you don't want two Inter-Integrated Circuit (I2C) Serial BUS after all.

 

In the diagram you'll see that the layout is colour coded with a legend; these are pins which are associated with one another purely by function (or not, in case of the green), and so they are a 'family' of pins that are useful together. But what if your project actually requires that you don't need SPI, or that you require two sets of SPI pins?

 

There are alternative functions for almost all of the pins. Here's a chart that helps to demonstrate what the alternative functions of the pins can be, and in bold and highlighted are what the defaults are for these pins:

 

 

Using these pins, they are referred to as 'ARM Peripherals', because after all, we're using an ARM processor by Broadcom. If you want to read into these in detail, you can look at the attached document. You'll find it pretty heavy going if you are not used to the technical information.

 

There are also useful libraries and websites which can help you to understand more about this information, such as The GPIO Utility by Wiring Pi and Gadgetoid and RogueHAL13's pinout.xyz - be careful not to be caught out though, as the GPIO pins are also referenced as 'BCM' pins (meaning Broadcom) to help reduce confusion from the physical pins.

 

Changing the default configuration is considered advanced, and isn't for the faint of heart, so enjoy going down the rabbit hole for your project!

 

Want to know more?

Meet The New Raspberry Pi 4 Model B - element14 Presents

Raspberry Pi 4 Model B - Technical Specifications

Raspberry Pi 4 Model B Frequently Asked Questions (FAQ)

Benchmarking the Raspberry Pi 4 Model B

Which accessories are compatible with the New Raspberry Pi 4 Model B?

Raspberry Pi 4 Model B Default GPIO Pinout with PoE Header

Do You Know Your Pi from Pie? Raspberry Pi Quiz!

Eben Upton talks about the new Raspberry Pi 4 Model B

 

Want to buy the new Raspberry Pi 4 Model B?

 

Product NameManufacturer
RASPBERRY PI 4 MODEL B, 1GBRaspberry PiBuy NowBuy Now
RASPBERRY PI 4 MODEL B, 2GBRaspberry PiBuy NowBuy Now
RASPBERRY PI 4 MODEL B, 4GBRaspberry PiBuy NowBuy Now
Attachments:
BCM2835-ARM-Peripherals.pdf
Anonymous

  • Awesome resource Element14. Hey this drawing has a colour coded legend on the bottom. Yeppie!

    Sean

  • Like the default pull up/down resistor states also

  • Fine. I received my PI4 with 4GB at the end of July,2019. Faster than I thought.

    Please check the PCB board with a magnifying glass. I found tin balls on it.

    They can roll under the IC devices.

     

    Best Regards

    Gerald

    ---

  • in reply to Grumpy_Mike

    I noticed recently somewhere in Pi documentation land that those I2C bus pins are specified as not to be used for anything other than connection to an EEPROM.

    However, it wasn't specified if there was an underlying SoC technical reason (e.g. crippled I2C bus, which would interest me) or just a HAT-friendly reason (which for my use-cases would not interest me).

    My main criticism of that 40-pin header is still the same for the past five years.. it's silly that there's no numbering, or at least marking on each tenth pin, on the Pi's silkscreen. It shouldn't cost anything (unless Sony factories are charging specifically by the paint-drop these days : ), and increases usability.

  • in reply to Grumpy_Mike

    They haven't updated the attached datasheet yet, a new one is forthcoming. I recommend you watch the video interview with Eben

  • in reply to cstanton

    No, look at the pin out. Pins 27 and 28 have always been I2C pins. It is just that the Pi foundation happened to label those as communication pins for the "HAT" ( Hardware on Top)  interface, to allow HATs to preload any drivers on boot up. They come up configured in this mode rather than the default GPIO inputs. All the alternative pin functions are defined in the data sheet. If you look at the Broadcom data sheet they have attached to this thread you will see the date on it is 2012, it is exactly the same data sheet I have from the launch of the PI.

     

    Nothing has changed with the GPIO on the Pi apart from the fact of the pin out between the 26 and 40 pin GPIO connector. All 40 pin GPIO connector Pis are, and remain, identical with regard of GPIO capability.

     

    Maybe you didn't know about these alternative functions previously?

  • in reply to Grumpy_Mike

    There's actually a change for the Raspberry Pi 4, and that's more SPI/i2c as I understand it.

  • What is all the fuss about alternative functions on the GPIO pins. Every Raspberry Pi from the very beginning has been able to do exactly this. There is no change or capabilities of the Model 4 in this respect.

  • in reply to rew

    Of course, other shops sell this as well.

    But I think the price may be a bit more expensive than Farnell's, just as I was able to verify it.

    Well, I ordered it, well, now I'm waiting a bit; Because I also needed other Raspberry products, so that's not a big problem.