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Adafruit 15x7 CharliePlex FeatherWing Created by lady ada https://learn.adafruit.com/adafruit-15x7-7x15-charlieplex-led-matrix-charliewing-featherwing Last updated on 2022-07-18 08:11:41 PM EDT ©Adafruit Industries Page 1 of 22 Table of Contents Overview 3 Pinouts 6 • Power Pins • I2C pins Arduino Usage 8 • Download Adafruit_IS31FL3731 library • Load Demo Library Reference • • • • Initialize Drawing Adafruit GFX Multiple Buffers Python & CircuitPython • • • • • • • 9 11 CircuitPython Microcontroller Wiring Python Computer Wiring CircuitPython Installation of IS31FL3731 Library Python Installation of IS31FL3731 Library CircuitPython & Python Usage Full Example Code Text Scrolling Example Python Docs 21 Downloads 21 • Datasheets & Files • Schematic • Fabrication Print ©Adafruit Industries Page 2 of 22 Overview You wont be able to look away from the mesmerizing patterns created by this Adafruit 15x7 CharliePlex LED Matrix Display FeatherWing.  This 15x7 LED display can be paired with with any of our Feather boards (https://adafru.it/nEt) for a beautiful, bright grid of 105 charlieplexed LEDs. It even comes with a built-in charlieplex driver that is run over I2C. We carry these FeatherWings in five vivid colors (http://adafru.it/29732520) ©Adafruit Industries Page 3 of 22 What is particularly nice about this Wing is the I2C LED driver chip has the ability to PWM each individual LED in a 15x7 grid so you can have beautiful LED lighting effects, without a lot of pin twiddling. Simply tell the chip which LED on the grid you want lit, and what brightness and it's all taken care of for you. You get 8-bit (256 level) dimming for each individual LED.  The IS31FL3731 is a nice little chip - and it runs happily over 3.3V power. Inside is enough RAM for 8 separate frames of display memory so you can set up multiple frames of an animation and flip them to be displayed with a single command. Since it uses I2C, it takes up only the SDA/SCL pins on your Feather and can share those pins with other I2C devices and sensors. ©Adafruit Industries Page 4 of 22 Our graphics library makes it easy to draw shapes, text and bitmaps for some strikingly beautiful LED displays. ©Adafruit Industries Page 5 of 22 Pinouts The 7x15 backpack makes it really easy to add a 105-LED display The LEDs themselves do not connect to the Feather. Instead, a matrix driver chip (IS31FL3731) does the multiplexing for you. The Feather simply sends i2c commands to the chip to tell it what LEDs to light up & how bright, and it is handled for you. This takes a lot of the work and pin-requirements off the Feather. Since it uses only I2C for control, it works with any Feather and can share the I2C pins for other sensors or displays. Power Pins The LED matrix uses only the 3V (second from left) and GND (fourth from left) pins for power and logic. Current draw depends on how many LEDs are lit but you can approximate it as about 40mA for most uses. ©Adafruit Industries Page 6 of 22 Note that the 3.3V power supply is a tiny bit lower than the forward voltage for the pure green, blue and white LED matrices but we didn't find any significant degredation in brightness. Really, they're still very bright. I2C pins All LED control is done over I2C using the IS31FL3731 interface library. This means SD A (rightmost) and SCL (to the left of SDA) must be connected, see above for those pins. The default address is 0x74 but you can change the address to 0x77 by bridging solder onto the address jumper ©Adafruit Industries Page 7 of 22 Arduino Usage Download Adafruit_IS31FL3731 library To begin reading sensor data, you will need to download Adafruit_IS31FL3731 and Adafruit_GFX from the Arduino library manager. Open up the Arduino library manager: Search for the Adafruit IS31FL3731 library and install it Search for the Adafruit GFX library and install it If using an earlier version of the Arduino IDE (prior to 1.8.10), also locate and install Ad afruit_BusIO (newer versions will install this dependency automatically). We also have a great tutorial on Arduino library installation at: http://learn.adafruit.com/adafruit-all-about-arduino-libraries-install-use (https:// adafru.it/aYM) ©Adafruit Industries Page 8 of 22 Load Demo Open up File->Examples->Adafruit_IS31FL3731->featherswirldemo and upload to your Feather + CharliePlex Matrix Feather You must update the code before uploading! At the top of the sketch, find the code that says // If you're using the full breakout... Adafruit_IS31FL3731 ledmatrix = Adafruit_IS31FL3731(); // If you're using the FeatherWing version //Adafruit_IS31FL3731_Wing ledmatrix = Adafruit_IS31FL3731_Wing(); and uncomment the last line and recomment the second line so you have: // If you're using the full breakout... //Adafruit_IS31FL3731 ledmatrix = Adafruit_IS31FL3731(); // If you're using the FeatherWing version Adafruit_IS31FL3731_Wing ledmatrix = Adafruit_IS31FL3731_Wing(); Upload to your Arduino, you'll see the LED display swirl different brightnesses! Library Reference Now that you have the demo working, you can control the matrix directly. ©Adafruit Industries Page 9 of 22 Initialize Start by creating a new matrix object with something like: Adafruit_IS31FL3731 ledmatrix = Adafruit_IS31FL3731(); There's no arguments to the constructor Then in your setup, call begin(address) to initialize the driver. Begin() will return false if the matrix was not found, and true if initialization worked out if (! ledmatrix.begin()) { Serial.println("IS31 not found"); while (1); } Serial.println("IS31 found!"); Drawing You can then draw to the display. Note that since we write directly to the driver RAM, any pixels 'drawn' will appear immediately. You can start with drawPixel(x, y, brightness) where x ranges between 0 and 15 inclusive, and y ranges between 0 and 8 inclusive. Brightness is the PWM of the LED, 0 is off, and 255 is all the way on. This loop will light up every LED in increasing brightness: int i = 0; for (uint8_t x=0; x> prompt. Python Installation of IS31FL3731 Library You'll need to install the Adafruit_Blinka library that provides the CircuitPython support in Python. This may also require enabling I2C on your platform and verifying you are running Python 3. Since each platform is a little different, and Linux changes often, please visit the CircuitPython on Linux guide to get your computer ready (https: //adafru.it/BSN)! Once that's done, from your command line run the following command: • sudo pip3 install adafruit-circuitpython-is31fl3731 adafruitcircuitpython-framebuf If your default Python is version 3 you may need to run 'pip' instead. Just make sure you aren't trying to use CircuitPython on Python 2.x, it isn't supported! CircuitPython & Python Usage To demonstrate the usage of the sensor we'll initialize it and manipulate the LED matrix from the board's Python REPL. NOTE: Due to size and design of each CharliePlex matrix form-factor, import and initialisation is different for each. Make sure you're running the correct code for your matrix! ©Adafruit Industries Page 14 of 22 First, run the following code to import the necessary modules: import board import busio If you're using the CharliePlex breakout, initialise it by running the following code: from adafruit_is31fl3731.matrix import Matrix as Display If you're using the CharliePlex FeatherWing, run the following code: from adafruit_is31fl3731.charlie_wing import CharlieWing as Display If you're using the CharliePlex Bonnet, run the following code: from adafruit_is31fl3731.charlie_bonnet import CharlieBonnet as Display Now, no matter which board you are using, you'll create the I2C object and pass that into Display . i2c = busio.I2C(board.SCL, board.SDA) display = Display(i2c) When the display initializes it will go through and clear each frame (there are 8 frames total) of the display. You might see the display momentarily flash and then turn off to a clear no pixel lit image. You can control all of the board's pixels using the fill function. Send to this function a value from 0 to 255 where 0 is every LED pixel turned off and 255 is every LED pixel turned on to maximum brightness. For example to set all the pixels to half their brightness run: display.fill(127) ©Adafruit Industries Page 15 of 22 You might notice some buzzing or ringing sounds from the display when all pixels are lit, this is normal as the Charlieplex driver quickly switches LEDs on and off. If you've used other displays like LED matrices you might notice the Charlieplex module doesn't need to have a show function called to make the changes visible.  As soon as you call fill or other display functions the display will update! You can turn all the pixels off with fill set to 0 : display.fill(0) Be careful setting all pixels to 255 maximum brightness! This might pull more power than your computer's USB port can provide if you are powering your board over USB. Use an external powers supply or battery when lighting lots of LEDs to max brightness. Now for some fun!  You can set any of the LED pixels using the pixel function.  This function takes the following parameters: • X position - The location of the horizontal / X pixel position. • Y position - The location of the vertical / Y pixel position. ©Adafruit Industries Page 16 of 22 • Intensity - This is a value from 0 to 255 which specifies how bright the pixel should be, 0 is off and 255 is maximum brightness.  Use an in-between value to show a less bright pixel. For example to set pixel 0, 0 to full brightness run: display.pixel(0, 0, 255) Or to set the pixel next to it horizontally to half brightness run: display.pixel(1, 0, 127) You can turn off individual pixels by setting them to an intensity of zero. You can even make pixels blink!  The board supports a fixed blink rate that you set using the blink function.  This function takes in the number of milliseconds to use for the blink rate (but internally it can only blink in 270ms increments so you might not get an exact match).  For example to blink pixels about once every half second call: display.blink(500) ©Adafruit Industries Page 17 of 22 You'll notice nothing actually changes on the board. This is because in addition to intensity each LED pixel has a blink state which can be enabled and disabled. The fi ll command can actually set all pixels and turn them on to blink: display.fill(127, blink=True) You can turn off the blinking by setting blink=False . The pixel command supports the blink parameter too!  You can turn on and off blinking pixel by pixel as needed.  For example to turn on blinking for pixel 0, 0 : display.pixel(0, 0, 127, blink=True) Currently the Charlieplex module is very simple and only exposes pixel set commands.  In the future more advanced graphics commands like line drawing, text display, etc. might be implemented but for now you'll need to manipulate the pixels yourself. Finally the display supports holding up to 8 frames of pixel data.  Each frame contains an entire matrix of LED pixel state (intensity, blinking, etc.) and by default the module starts you on frame 0.  You can change to start displaying and drawing on another frame by calling frame which takes these parameters: • Frame number - This is the frame number to make the active frame for display or drawing.  There are 8 frames total, 0 through 7 . • show - An optional boolean that defaults to True and specifies if the frame should be immediately displayed ( True ) or just made active so that pixel and fill commands draw on it but it's not yet shown. For example to clear frame 1 and draw a few pixels on it, then display it you can run: display.frame(1, display.fill(0) display.pixel(0, display.pixel(1, display.pixel(2, display.frame(1) ©Adafruit Industries show=False) 0, 1, 2, # 255) 255) 255) show=True is the default, the frame will be displayed! Page 18 of 22 Notice how the first call switches to make frame 1 the active frame but doesn't display it because show is set to false. Then the frame pixel data is changed with fill and pixel commands, and finally the frame is shown by calling frame again but letting the default show = True be used so the frame is displayed. Using frames you can build simple animations by drawing each frame and swapping between them over time! That's all there is to the basic Charlieplex driver module usage! Full Example Code # SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries # SPDX-License-Identifier: MIT import board import busio # uncomment next line if you are using Feather CharlieWing LED 15 x 7 from adafruit_is31fl3731.charlie_wing import CharlieWing as Display # # # # # # # # uncomment next line if you are using Adafruit 16x9 Charlieplexed PWM LED Matrix from adafruit_is31fl3731.matrix import Matrix as Display uncomment next line if you are using Adafruit 16x8 Charlieplexed Bonnet from adafruit_is31fl3731.charlie_bonnet import CharlieBonnet as Display uncomment next line if you are using Pimoroni Scroll Phat HD LED 17 x 7 from adafruit_is31fl3731.scroll_phat_hd import ScrollPhatHD as Display uncomment next line if you are using Pimoroni 11x7 LED Matrix Breakout from adafruit_is31fl3731.matrix_11x7 import Matrix11x7 as Display # uncomment this line if you use a Pico, here with SCL=GP21 and SDA=GP20. # i2c = busio.I2C(board.GP21, board.GP20) i2c = busio.I2C(board.SCL, board.SDA) display = Display(i2c) # draw a box on the display # first draw the top and bottom edges for x in range(display.width): display.pixel(x, 0, 50) display.pixel(x, display.height - 1, 50) # now draw the left and right edges ©Adafruit Industries Page 19 of 22 for y in range(display.height): display.pixel(0, y, 50) display.pixel(display.width - 1, y, 50) Text Scrolling Example NOTE: When running this example on Raspberry Pi, you must have the font8x5.bin file found here (https://adafru.it/Edh) in the same directory as the program! wget https://raw.githubusercontent.com/adafruit/ Adafruit_CircuitPython_framebuf/master/examples/font5x8.bin # SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries # SPDX-License-Identifier: MIT import board import busio import adafruit_framebuf # uncomment next line if you are using Feather CharlieWing LED 15 x 7 # from adafruit_is31fl3731.charlie_wing import CharlieWing as Display # uncomment next line if you are using Adafruit 16x9 Charlieplexed PWM LED Matrix # from adafruit_is31fl3731.matrix import Matrix as Display # uncomment next line if you are using Adafruit 16x8 Charlieplexed Bonnet from adafruit_is31fl3731.charlie_bonnet import CharlieBonnet as Display # # # # uncomment next line if you are using Pimoroni Scroll Phat HD LED 17 x 7 from adafruit_is31fl3731.scroll_phat_hd import ScrollPhatHD as Display uncomment next line if you are using Pimoroni 11x7 LED Matrix Breakout from adafruit_is31fl3731.matrix_11x7 import Matrix11x7 as Display # uncomment this line if you use a Pico, here with SCL=GP21 and SDA=GP20. # i2c = busio.I2C(board.GP21, board.GP20) i2c = busio.I2C(board.SCL, board.SDA) display = Display(i2c) text_to_show = "Adafruit!!" # Create a framebuffer for our display buf = bytearray(32) # 2 bytes tall x 16 wide = 32 bytes (9 bits is 2 bytes) fb = adafruit_framebuf.FrameBuffer( buf, display.width, display.height, adafruit_framebuf.MVLSB ) frame = 0 # start with frame 0 while True: for i in range(len(text_to_show) * 9): fb.fill(0) fb.text(text_to_show, -i + display.width, 0, color=1) # to improve the display flicker we can use two frame # fill the next frame with scrolling text, then # show it. display.frame(frame, show=False) # turn all LEDs off display.fill(0) for x in range(display.width): # using the FrameBuffer text result ©Adafruit Industries Page 20 of 22 bite = buf[x] for y in range(display.height): bit = 1 0 then set the pixel brightness if bit: display.pixel(x, y, 50) # now that the frame is filled, show it. display.frame(frame, show=True) frame = 0 if frame else 1 Python Docs Python Docs (https://adafru.it/C55) Downloads Datasheets & Files • EagleCAD PCB Files on GitHub (https://adafru.it/nEB) • Fritzing objects in Adafruit Fritzing library (https://adafru.it/aP3) • IS31FL3731 Library (https://adafru.it/lWA) • IS31FL3731 Datasheet (https://adafru.it/lWC) Schematic Click to embiggen ©Adafruit Industries Page 21 of 22 Fabrication Print Dimensions in inches ©Adafruit Industries Page 22 of 22