Overview

You can now create a dazzling display with your Raspberry Pi with the Adafruit RGB Matrix HAT or Bonnet. These boards plug into your Pi and makes it super easy to control RGB matrices such as those we stock in the shop and create a colorful scrolling display or mini LED wall with ease.

The RGB Matrix HAT works on any Raspberry Pi with a 40-pin GPIO header — Zero, Zero W/WH, Model A+, B+, Pi 2 and Pi 3. It does not work with older 26-pin boards like the original Model A or B. Note with the Pi Zero you may need to solder a header on the Pi board; it’s normally unpopulated on that model (except the “Zero WH”).

This HAT is our finest to date, full of some really great circuitry. Let me break it down for you:

  • Simple design - plug in power, plug in IDC cable, run our Python code!
  • Power protection circuitry - you can plug a 5V 4A wall adapter into the HAT and it will automatically protect against negative, over or under-voltages! Yay for no accidental destruction of your setup.
  • Onboard level shifters to convert the RasPi's 3.3V to 5.0V logic for clean and glitch free matrix driving
  • DS1307 Real Time Clock can keep track of time for the Pi even when it is rebooted or powered down, to make for really nice time displays

Works with any of our 16x32, 32x32 or 32x64 RGB LED Matrices with HUB75 connections. The latest “Rev C” HAT also supports 64x64 matrices by soldering a small jumper on the PCB. You can even chain multiple matrices together for a longer display - we've only tested up to 32x128 but it works just fine. The bigger the display the harder it is on the Pi, so keep that in mind if you're using a lower-powered Pi Zero.

Please note: this HAT is only for use with HUB75 type RGB Matrices. Not for use with NeoPixel, DotStar, or other 'addressable' LEDs.

Each order comes with a HAT PCB with all surface mount parts assembled, a 2x20 female socket connector, a 2 pin terminal block, and a 2x8 IDC socket connector. A CR1220 coin cell is not included to make air shipping easier, please order one seperately if you do not have one and would like to use the real time clock.

RGB Matrix is not included, please check out our fine selection!

A 5V power supply is also required, not included, for power the matrix itself, the Pi cannot do it, to calculate the power, multiply the width of all the chained matrices * 0.12 Amps : A 32 pixel wide matrix can end up drawing 32*0.12 = 3.85A so pick up a 5V 4A power supply.

Raspberry Pi not included (but we have 'em in the shop so pick one up, Model A+, B+, Pi 2 or Pi 3)

Some light soldering is required to attach the headers to your Pi. A soldering iron and solder are required, but it’s a simple soldering job and most beginners can do it in about 15 minutes.

Pinouts

This HAT uses a lot of pins to drive the RGB Matrix. You'll still have a couple left over but just be aware a majority are in use by the matrix.

Unused GPIO pins include: RX, TX, 25, MOSI, MISO, SCLK, CE0, CE1, 19.

Pin 24 is free if you are not using a 1/32 scan (i.e. 64x64) matrix.

Pin 18 is free if using the “convenience” (vs “quality”) setting during installation.

The 1-Wire interface as enabled by raspi-config will interfere with the operation of the matrix! By default it uses pin 4. If you are connecting any 1-Wire devices, specify a different pin (any of the above) in /boot/config.txt, for example:

dtoverlay=w1-gpio gpiopin=19

I2C / RTC pins

The DS1307 Real Time Clock soldered onboard is connected to the I2C pins SDA and SCL - these can still be used for other I2C sensors and devices as long as they are not on address 0x68

To use the Real Time Clock, a CR1220 3V lithium battery is required.

5V protection circuitry and backpower diode

LED matrix panels require 5V power and a lot of it! 5V 2A at a minimum and you can easily need a 5V 4A or 5V 10A supply for big stretches of panels!

Each matrix has 64 pixels (16x32 or 32x32 panels) or 128 pixels (for the 32x64 panels) lit at one time. Each pixel can draw up to 0.06 Amps each if on full white. The total max per panel is thus 64 * 0.06 = 3.95 Amps or 128 * 0.06 = 7.68 Amps

That's if all the LEDs are on at once, which is not likely - but still, its good to have at least half for the power supply in case you get bright!

5V power from a wall plug goes into the DC jack on the HAT which then goes through a fancy protection circuit that makes sure the voltage is not higher than 5.8V - this means that if you accidentally grab a 9V or 12V plug or a reverse polarity plug you will not damage the HAT, Pi and panels.  (Please note, this does not protect against extreme damage, if you plug in a 120VAC output into the DC jack or continuously try to plug in the wrong voltage you could still cause damage so please do be careful!)

We recommend powering your driving Raspberry Pi from the Pi's microUSB port but we do have a 1A diode on board that will automatically power the Pi if/when the voltage drops. So if you want, just plug in the 5V wall adapter into the HAT and it will automagically power up the Pi too!

The green LED next to the DC jack will indicate that the 5V power is good, make sure it is lit when trying to use the HAT!

Matrix Drive pins

The matrix does not work like 'smart' pixels you may have used, like NeoPixels or DotStars or LPD8806 or WS2801 or what have you. The matrix panels are very 'dumb' and have no memory or self-drawing capability.

Data must be constantly streamed to the matrix for an image to display! So all of these pins are always used when drawing to the display

All these pins go thru a 74AHCT145 level shifter to convert the 3.3V logic from the Pi to the 5V logic required by the panels

Matrix Color Pins

  • Pi GPIO #5 - Matrix R1 (Red row 1) pin
    This pin controls the red LEDs on the top half of the display
  • Pi GPIO #13 - Matrix G1 (Green row 1) pin
    This pin controls the green LEDs on the top half of the display
  • Pi GPIO #6 - Matrix B1 (Blue row 1) pin
    This pin controls the blue LEDs on the top half of the display
  • Pi GPIO #12 - Matrix R2 (Red row 2) pin
    This pin controls the red LEDs on the bottom half of the display
  • Pi GPIO #16 - Matrix G2 (Green row2) pin
    This pin controls the green LEDs on the bottom half of the display
  • Pi GPIO #23 - Matrix B2 (Blue row 2) pin
    This pin controls the blue LEDs on the bottom half of the display

Matrix Control pins

  • Pi GPIO #4 - Matrix OE (output enable) pin
    This pin controls whether the LEDs are lit at all
  • Pi GPIO #17 - Matrix CLK (clock) pin
    This pin is the high speed clock pin for clocking RGB data to the matrix
  • Pi GPIO #21 - Matrix LAT (latch) pin
    This pin is the data latching pin for clocking RGB data to the matrix

RGB Matrix Address pins

  • Pi GPIO #22 - Matrix A (address A) pin
    This pin is part of the 1->16 or 1->8 multiplexing circuitry.
  • Pi GPIO #26 - Matrix B (address B) pin
    This pin is part of the 1->16 or 1->8 multiplexing circuitry.
  • Pi GPIO #27 - Matrix C (address C) pin
    This pin is part of the 1->16 or 1->8 multiplexing circuitry.
  • Pi GPIO #20 - Matrix D (address D) pin
    This pin is part of the 1->32, 1->16 multiplexing circuitry. Used for 32-pixel and 64-pixel tall displays only
  • Pi GPIO #24 - Matrix E (address E) pin
    This pin is part of the 1->32 multiplexing circuitry. Used for 64-pixel tall displays only. Present on newer “Rev C” HATs only. Requires minor soldering, explained on next page.

Assembly

Solder on Headers and Terminal Block

Before we can a-blinkin' there's a little soldering to be done. This step will attach the 2x20 socket header so that we can plug this HAT into a Raspberry Pi, the 2x8 header so we can plug the RGB matrix into the HAT, and a terminal block so you can power the matrix through the HAT.

Start by plugging the 2x20 header into a Raspberry Pi, this will keep the header stable while you solder. Make sure the Pi is powered off!

Place the HAT on top so that the short pins of the 2x20 header line up with the pads on the HAT

And Solder!

Heat up your iron and solder in one header connection on the right.

Once it is soldered, put down the solder and reheat the solder point with your iron while straightening the HAT so it isn't leaning down


(For tips on soldering, be sure to check out our Guide to Excellent Soldering).

Solder one point on the opposite side of the connector

Solder each of the connections for the top row

Flip the board around and solder all the connections for the other half of the 2x20 header

Check over your work so far, make sure each solder point is shiny, and isn't bridged or dull or cracked

Place the 2 pin terminal block first, make sure the two 'mouths' are facing outwards

Use some tape to stick the terminal down in place

Flip the board over, the tape should keep the terminal block in place

Solder the two big connections, use plenty of solder!

Check your work, the connections should be solid and shiny

Next up we will attach the 2x8 IDC header. Unlike the 2x20 header, this connector has a direction!

Notice in the middle there's an outline for the connector in the middle. On the right it says HUB75 and on the left of the connector there is a little 'cutout' shape. This cutout shape must match up with the cut out on the connector.

If you solder it in backwards, its not a huge deal, you can use diagonal cutters to cut out a notch on the opposite side, but if you get it right then you will never have to worry about plugging in your matrix data cable the wrong way

Place the connector in the slot so that the notched side is on the left

Use some tape to hold the IDC connector in place

Flip the board over, the tape should keep the connector from falling out

Solder in all the pins like you did with the 2x20 connector

Check your work! Make sure all the solder points are clean and not shorted or cracked or dull

Flip the board around & solder up the other half!

Check your work one last time...now continue to testing!

64x64 Matrices: Solder “E” Jumper

64x64 matrices are supported on the latest “Rev C” HATs only.

Look for the Address E pads located between the HUB75 connector and Pi camera cutout.

Melt a blob of solder between the center “E” pad the the “8” pad just above it (for 64x64 matrices in the Adafruit shop)…or the “16” pad below (rare, for some third-party 64x64 matrices…check datasheet).

Driving Matrices

OK we're onto the fun part now! Be sure you have completed the Assembly step before continuing, the soldering is not optional

Step 1. Plug HAT/Bonnet into Raspberry Pi

Shut down your Pi and remove power. Plug the HAT or Bonnet on so all the 2x20 pins go into the GPIO header.

Step 2. Connect Matrix Power cable to terminal block

Your RGB matrix came with a red & black power cable. One end has a 4-pin MOLEX connector that goes into the matrix. The other end probably has a spade connector. If you didn't get a spade connector, you may have to cut off the connector and tin the wires to plug them into the terminal block

Either way, unscrew the terminal blocks to loosen them

Plug the red wire into the + side, and the black wire into the - side.

Step 3. Connect RGB Matrix Data cable to IDC

The RGB matrix also came with a 2x8 data cable. Connect one end to the matrix's INPUT side and the other end to the IDC socket on the HAT/bonnet.

It wont damage the matrix if you accidentally get the cable connected to the output end of the matrix but it wont work so you might as well get it right first time!

If you're using a 64x64 RGB matrix and either a Bonnet or a Rev C HAT, use your soldering iron to melt a blob of solder on the bottom solder jumper so the middle pad is 'shorted' to 8. (This is compatible with 64x64 matrices in the Adafruit store. For 64x64 matrices from other sources, you might need to use 16 instead, check the datasheet.)

Step 4. Power up your Pi via MicroUSB (optional but suggested)

Connect your Raspberry Pi to power via the microUSB cable, just like you normally would to power it up.

You can power the Pi via the 5V wall plug that is also used for the Matrix but its best to have it powered seperately

Step 5. Plug in the 5V DC power for the Matrix

OK now you can plug in your 5V 2A or 4A or larger wall adapter into the HAT/bonnet. This will turn the green LED on but nothing will display on your matrix yet because no software is running!

Check that the Matrix plugs are installed and in the right location

IDC goes into the INPUT side (look for any arrows, arrows point from INPUT side to OUTPUT)

Power plug installed, red wires go to VCC, black wires to GND

Step 6. Log into your Pi to install and run software

OK now you are ready to run the Pi software. You will need to get into a command line via the HDMI monitor, ssh or console cable. You will also need to make sure your Pi is on the Internet via a WiFi or Ethernet connection.

We have a script that downloads the code and any prerequisite software. It works with the current Raspbian “Stretch” operating system (either the Lite or Desktop version):

curl https://raw.githubusercontent.com/adafruit/Raspberry-Pi-Installer-Scripts/master/rgb-matrix.sh >rgb-matrix.sh
sudo bash rgb-matrix.sh

The LED-matrix library is (c) Henner Zeller [email protected] with GNU General Public License Version 2.0 http://www.gnu.org/licenses/gpl-2.0.txt

Earlier versions of this guide used our own fork of this library. That’s deprecated now, but still available if you have existing code built atop it. Otherwise, use this installer script and latest code.

When first run, the script will explain its plans and give you the option to cancel.

Of particular note here: any existing installation will be replaced. If there is a directory called “rpi-rgb-led-matrix” in the current working directory, its contents will be overwritten. Additionally, a Python module is installed and will replace anything currently there. If this is a problem, cancel and make a backup. Otherwise, sometimes reinstalling is exactly what you want.

Next the script will ask you what kind of adapter you’re using between the Pi and RGB matrix: either an Adafruit RGB Matrix Bonnet, or RGB Matrix HAT with RTC. If you select the latter, you’ll also be asked if you want to install additional drivers for the realtime clock.

Then you’re asked whether you need the absolute best image possible from the LED matrix, or can accept slightly reduced quality for the sake of simplicity.

The “quality” option comes at a cost. First, you need to solder a jumper wire between GPIO4 and GPIO18 on the Bonnet or Hat board. Also, the normal sound output of the Raspberry Pi must be disabled. You can still use a USB sound adapter if needed, but audio over HDMI or from the 1/8" jack will not be present.

The “convenience” setting requires no changes and sound still works. For many casual projects this might look good enough. There’s an occasional bit of flicker from the matrix, that’s all.

If you’re not sure, or if you just want to get started experimenting with your new gadget, select “convenience” for now. You can make the change and reinstall the software later if needed.

The script will confirm your selections and offer one more chance to cancel without changes.

There’s a lot of software to update, download and install, so it may take up to 15 minutes or so to complete. Afterward, you’ll be asked whether you want to reboot the system. If you’ve selected to install RTC support (for the Matrix HAT + RTC) or have made a change in the “quality” vs “convenience” setting, a reboot is required.

All other settings (LED matrix size, number of “chained” matrices and so forth) are specified at run-time.

Overclocked Raspberry Pi boards may produce visual glitches on the LED matrix. If you encounter such trouble, first thing to try is to set the Pi to the default (non-overclocked) speed using raspi-config, then reboot and retest.

Testing the Examples

The installer creates a directory called rpi-rgb-led-matrix, and inside this is a subdirectory examples-api-use with a few programs we can use to experiment with the matrix and confirm everything’s working.

All of the examples — and any code using the companion libraries — accept a common set of command-line switches for specifying the LED matrix size and other options. Among the more vital options are:

--led-rows=(rows)

Specifies the number of rows (or height or the number of pixels vertically) of your LED matrix (or matrices, if you have several chained…they all need to be the same size though). Default value if unspecified is 32. Maximum value with the Adafruit RGB Matrix HAT + RTC is 32. Maximum with the RGB Matrix Bonnet is 64.

--led-cols=(columns)

Specifies the number of columns (or width or the number of pixels horizontally) of your LED matrix/matrices. Default value if unspecified is 32.

--led-chain=(chained)

Specifies the number of matrices in the chain…the output of one connects to the input of the next. Default value if unspecified is 1.

Here’s how to run one of the examples — a rotating colored square. Because this code is performing low-level hardware operations, it must be run using the sudo command:

sudo ./demo -D0 --led-rows=32 --led-cols=16

That’s for a single 32x16 pixel RGB matrix. If you have a different size, change the --led-rows and/or --led-cols values. Add a --led-chain value if multiple matrices are chained.

There are 12 different examples in the demo program (0 through 11), chosen with -D. For a full list of the program’s options, just type demo.

Depending on your matrix type and Raspberry Pi model, some additional options may need fine-tuning:

--led-slowdown-gpio=(0…2) Sometimes needed to “throttle back” the speed when using a fast Pi with a slower panel. Default is 1.

--led-rgb-sequence=(RGB order) Some LED matrices may have their red, green and blue LEDs wired up in a different order…for example, if you need to swap the green and blue channels, use --led-rgb-sequence=RBG. Default is RGB.

--led-pwm-bits=(1…11) For long matrix chains you’ll probably need to use fewer PWM bits, sacrificing some color fidelity to improve refresh speed. Default is 11.

There are still many additional options but they’re increasingly esoteric and might only be needed with RGB matrices from other sources. For a complete explanation of these options (and a more in-depth explanation of the options above) see the documentation accompanying hzeller’s code repository.

The demos kinda run, but I’m seeing weird rectangles and glitches.

If your Pi is overclocked, or if you’re using a Raspberry Pi 2, you may need to dial back the matrix control speed slightly. This can be done with the --led-slowdown-gpio=2 setting. Conversely, early Raspberry Pis (Model A, B and similar) might get an improved image by speeding up the matrix code with a value of 0 here.

There are a few additional examples in that directory showing how to write C++ programs to draw to the matrix. Look through the source code and Makefile to see how this is done and how to link with the rgbmatrix library. And there’s more documentation in the hzeller repository, including initializing the matrix size and chain length in your code so it’s not necessary to specify this on the command line every time.

Using the Python Library

Some Python examples are included in the rpi-rgb-led-matrix/bindings/python/samples directory. The matrix installer script has already loaded the prerequisite Python Imaging Library and installed the rgbmatrix module for both Python 2.7 and Python 3.

Again, more documentation is available in the library author’s repository, and some of the examples show how to specify the matrix size and chain length in code rather than command-line selections every time.

While the rgbmatrix module provides its own drawing operations, it can also work with the Python Imaging Library as an “offscreen canvas” that’s then issued to the matrix with the SetImage() or SwapOnVSync() function — see the examples with “image-” in their name.

Core PIL image functions are explained here: The Image Module

Graphics functions (lines, etc.) are here: The ImageDraw Module

Reminder: the older Adafruit fork of the RGB matrix library is still available if you need it for existing code, but consider this deprecated. For new projects we recommend the more up-to-date hzeller code installed by the rgb-matrix.sh script!

Using the RTC

We had a little space and thought a real time clock would be a nice pairing for this HAT so we tossed on a DS1307 real time clock (RTC). This clock uses a 32.768KHz crystal and backup battery to let the HAT & Pi keep track of time even when power is lost and there's no network access. This makes it great for time displays!

A 12mm 3V Lithium Coin Cell (CR1220) is REQUIRED to use the RTC! It will not work without one!

The rgb-matrix.sh script already installed the necessary software to use the realtime clock…but you’ll need to set the initial time once. This is explained in the Sync time from Pi to RTC” section of this DS1307 tutorial (just that one section…you can ignore the rest).

HELP!

I'm using a Raspberry Pi 2 and things are all not working right!

Run sudo raspi-config and in the “Overclock” options set the core frequency to 350 MHz or less. Reboot and see if the image is stable. There seems to be an issue when toggling GPIO too quickly.

Also see the “Driving Matrices” page for notes about dialing back the GPIO speed.

The matrix flashes on and off when in use

If you’re interfacing to any 1-wire devices, and if you’ve enabled 1-wire via raspi-config, you’ll need to use something other than the default pin 4. Pins 19 or 25 make good choices. Look for the line in /boot/config.txt where 1-wire is enabled and tell it which pin to use:

dtoverlay=w1-gpio gpiopin=19

Downloads

Schematic

Click to embiggen

Fabrication Print

Here's the fabrication print with dimensions in inches. This HAT is compatible with the Raspberry Pi mechanical HAT specification!

This guide was first published on Jan 16, 2015. It was last updated on Oct 19, 2018.