Overview

Add some jazz & pizazz to your project with a color touchscreen LCD. This TFT display is big (3.5" diagonal) bright (6 white-LED backlight) and colorful! 480x320 pixels with individual RGB pixel control, this has way more resolution than a black and white 128x64 display, and double our 2.8" TFT. As a bonus, this display has a resistive touchscreen attached to it already, so you can detect finger presses anywhere on the screen.

This display has a controller built into it with RAM buffering, so that almost no work is done by the microcontroller. The display can be used in two modes: 8-bit or SPI. For 8-bit mode, you'll need 8 digital data lines and 4 or 5 digital control lines to read and write to the display (12 lines total). SPI mode requires only 5 pins total (SPI data in, data out, clock, select, and d/c) but is slower than 8-bit mode. In addition, 4 pins are required for the touch screen (2 digital, 2 analog) or you can purchase and use our resistive touchscreen controller (not included) to use I2C or SPI.

Of course, we wouldn't just leave you with a datasheet and a "good luck!". For 8-bit interface fans we've written a full open source graphics library that can draw pixels, lines, rectangles, circles, text, and more. For SPI users, we have a library as well, its separate from the 8-bit library since both versions are heavily optimized. We also have a touch screen library that detects x, y and z (pressure) and example code to demonstrate all of it.

Pinouts

The 3.5" TFT display on this breakout supports many different modes - so many that the display itself has 50 pins. However, we think most people really only use 2 different modes, either "SPI" mode or 8-bit mode. Each 'side' of the display has all the pins required for that mode. You can switch between modes, by rewiring the display, but it cannot be used in two modes at the same time!

All logic pins, both 8-bit and SPI sides, are 3-5V logic level compatible, the 74LVX245 chips on the back perform fast level shifting so you can use either kind of logic levels. If there's data output, the levels are at at 3.3V

SPI Mode

This is what we think will be a popular mode when speed is not of the utmost importance. It doesn't use as many pins (only 4 to draw on the TFT if you skip the MISO pin), is fairly flexible, and easy to port to various microcontrollers. It also allows using a microSD card socket on the same SPI bus. However, its slower than parallel 8-bit mode because you have to send each bit at a time instead of 8-bits at a time. Tradeoffs!

  • GND - this is the power and signal ground pin
  • 3-5V / Vin - this is the power pin, connect to 3-5VDC - it has reverse polarity protection but try to wire it right!
  • 3.3Vout - this is the 3.3V output from the onboard regulator
  • CLK - this is the SPI clock input pin
  • MISO - this is the SPI Master In Slave Out pin, its used for the SD card mostly, and for debugging the TFT display. It isn't necessary for using the TFT display which is write-only
  • MOSI - this is the SPI Master Out Slave In pin, it is used to send data from the microcontroller to the SD card and/or TFT
  • CS - this is the TFT SPI chip select pin
  • D/C - this is the TFT SPI data or command selector pin
  • RST - this is the TFT reset pin. There's auto-reset circuitry on the breakout so this pin is not required but it can be helpful sometimes to reset the TFT if your setup is not always resetting cleanly. Connect to ground to reset the TFT
  • Lite - this is the PWM input for the backlight control. It is by default pulled high (backlight on) you can PWM at any frequency or pull down to turn the backlight off
  • Y+ X+ Y- X- these are the 4 resistive touch screen pads, which can be read with analog pins to determine touch points. They are completely separated from the TFT electrically (the overlay is glued on top)
  • IM2 IM1 IM0 - these are interface control set pins. In general these breakouts aren't used, and instead the onboard jumpers are used to fix the interface to SPI or 8-bit. However, we break these out for advanced use and also for our test procedures
  • Card CS / CCS - this is the SD card chip select, used if you want to read from the SD card.
  • Card Detect / CD - this is the SD card detect pin, it floats when a card is inserted, and tied to ground when the card is not inserted. We don't use this in our code but you can use this as a switch to detect if an SD card is in place without trying to electrically query it. Don't forget to use a pullup on this pin if so!

8-Bit Mode

This mode is for when you have lots of pins and want more speed. In this mode we send 8 bits at a time, so it needs way more pins, 12 or so (8 bits plus 4 control)! If your microcontroller

  • GND - this is the power and signal ground pin
  • 3-5V (Vin)- this is the power pin, connect to 3-5VDC - it has reverse polarity protection but try to wire it right!
  • CS - this is the TFT 8-bit chip select pin (it is also tied to the SPI mode CS pin)
  • C/D - this is the TFT 8-bit data or command selector pin (it is also tied to the SPI mode C/D pin)
  • WR - this is the TFT 8-bit write strobe pin. It is also connected to the SPI CLK pin
  • RD - this is the TFT 8-bit read strobe pin. You may not need this pin if you don't want to read data from the display
  • RST - this is the TFT reset pin. There's auto-reset circuitry on the breakout so this pin is not required but it can be helpful sometimes to reset the TFT if your setup is not always resetting cleanly. Connect to ground to reset the TFT
  • Backlite - this is the PWM input for the backlight control. It is by default pulled high (backlight on) you can PWM at any frequency or pull down to turn the backlight off
  • Y+ X+ Y- X- these are the 4 resistive touch screen pads, which can be read with analog pins to determine touch points. They are completely separated from the TFT electrically (the overlay is glued on top)
  • D0 thru D7 - these are the 8 bits of parallel data sent to the TFT in 8-bit mode. D0 is the least-significant-bit and D7 is the MSB

Wiring & Test

We tried to make this TFT breakout useful for both high-pin microcontrollers that can handle 8-bit data transfer modes as well as low-pincount micros like the Arduino UNO and Leonardo that are OK with SPI.

Essentially, the tradeoff is pins for speed. SPI is about 2-4 times slower than 8-bit mode, but that may not matter for basic graphics!

In addition, SPI mode has the benefit of being able to use the onboard microSD card socket for reading images. We don't have support for this in 8-bit mode so if you want to have an all-in-one image viewer type application, use SPI!

Assembling Header

Either way, if you're using a breadboard,  you'll need to solder header onto one or two of the sides. The procedure is the same for both sides

Prepare the header strip:

Cut the strip to length if necessary. It will be easier to solder if you insert it into a breadboard - long pins down

Add the breakout board:

Place the breakout board over the pins so that the short pins poke through the breakout pads

Add the breakout board:

Place the breakout board over the pins so that the short pins poke through the breakout pads

You're done! Check your solder joints visually and continue onto the next steps

8-Bit Wiring & Test

8-Bit Wiring

Wiring up the 8-bit mode is kind of a pain, so we really only recommend doing it for UNO (which we show) and Mega (which we describe, and is pretty easy since its 8 pins in a row). Anything else, like a Leonardo or Micro, we strongly recommend going with SPI mode since we don't have an example for that. Any other kind of 'Arduino compatible' that isn't an Uno, try SPI first. The 8-bit mode is hand-tweaked in the Adafruit_TFTLCD pin_magic.h file. Its really only for advanced users who are totally cool with figuring out bitmasks for various ports & pins.

Really, we'll show how to do the UNO but anything else? go with SPI!

Make sure you're soldering and connecting to the 8-bit side!

Part 1 - Power & backlight test

In these images we show using our 2.8" TFT but its the exact same pinout, just a tad smaller!

Begin by wiring up the 3-5VDC and GND pins.

Connect the 3-5V pin to 5V and GND to GND on your Arduino. I'm using the breadboard rails but you can also just wire directly.

Power it up and you should see the white backlight come on

Part 2 - Data Bus Lines

Now that the backlight is working, we can get the TFT LCD working. There are many pins required, and to keep the code running fairly fast, we have 'hardcoded' Arduino digital pins #2-#9 for the 8 data lines.
However, they are not in that order! D0 and D1 go to digital #8 and #9, then D2-D7 connect to #2 thru #7. This is because Arduino pins #0 and #1 are used for serial data so we can't use them

Begin by connecting D0 and D1 to digital #8 and 9 respectively as seen above. If you're using a Mega, connect the TFT Data Pins D0-D1 to Mega pins #22-23, in that order. Those Mega pins are on the 'double' header.

Now you can connect the remaining 6 pins over. Connect D2-D7 on the TFT pins to digital 2 thru 7 in that order. If you're using a Mega, connect the TFT Data Pins D2-D7 to Mega pins #24-29, in that order. Those Mega pins are on the 'double' header.

In addition to the 8 data lines, you'll also need 4 or 5 control lines. These can later be reassigned to any digital pins, they're just what we have in the tutorial by default.

  • Connect the third pin CS (Chip Select) to Analog 3
  • Connect the fourth pin C/D (Command/Data) to Analog 2
  • Connect the fifth pin WR (Write) to Analog 1
  • Connect the sixth pin RD (Read) to Analog 0

You can connect the seventh pin RST (Reset) to the Arduino Reset line if you'd like. This will reset the panel when the Arduino is Reset. You can also use a digital pin for the LCD reset if you want to manually reset. There's auto-reset circuitry on the board so you probably don't need to use this pin at all and leave it disconnected

The RD pin is used to read the chip ID off the TFT. Later, once you get it all working, you can remove this pin and the ID test, although we suggest keeping it since its useful for debugging your wiring.

OK! Now we can run some code

8-Bit Library Install

We have example code ready to go for use with these TFTs. It's written for Arduino, which should be portable to any microcontroller by adapting the C++ source.

Two libraries need to be downloaded and installed: first is the Adafruit_TFTLCD library (this contains the low-level code specific to this device), and second is the Adafruit GFX Library (which handles graphics operations common to many displays we carry). If you have Adafruit_GFX already, make sure its the most recent version since we've made updates for better performance

Download both ZIP files, uncompress and rename the folders to Adafruit_TFTLCD (contains Adafruit_TFTLCD.cpp and .h) and Adafruit_GFX (contains Adafruit_GFX.cpp and .h) respectively. Then place them inside your Arduino libraries folder and restart the Arduino IDE. If this is all unfamiliar, we have a tutorial introducing Arduino library concepts and installation.

Prepare TFTLCD Library

In the Adafruit_TFTLCD Library folder, you may need to edit Adafruit_TFTLCD.h. On about line 12, you will see

#define USE_ADAFRUIT_SHIELD_PINOUT

Make sure this line is commented out with a // in front (it should but if you're having issues, its worth checking.

Next up, we originally designed this library for 320x240 TFTs. Since this is a 480x320, we  have to adjust the size the library is expecting. Open up Adafruit_TFTLCD.cpp and find these lines:

Comment out the 240 and 320 lines, and uncomment the 320 and 480 lines:

Save it, now you can upload the demo!

After restarting the Arduino software, you should see a new example folder called Adafruit_TFTLCD and inside, an example called graphicstest. Upload that sketch to your Arduino. 

You may need to press the Reset button to reset the Arduino and TFT. You should see a collection of graphical tests draw out on the TFT.

(The images below shows SPI wiring but the graphical output should be similar!)

 If you're having difficulties, check the serial console.The first thing the sketch does is read the driver code from the TFT. It should be 0x8357 (for the HX8357D controller inside)

If you Unknown Driver Chip then it's probably something with your wiring, double check and try again!

SPI Wiring & Test

Don't forget, we're using the SPI interface side of the PCB!

SPI Mode Jumpers

Before you start, we'll need to tell the display to put us in SPI mode so it will know which pins to listen to. To do that, we have to connect the IM2 pin to 3.3V. The easiest way to do that is to solder closed the IM2 jumper on the back of the PCB. Turn over the PCB and find the solder jumper:

With your soldering iron, melt solder to close the jumper indicated IM2

If you really don't want to solder, you can also wire the breakout pin to the 3vo pin, just make sure you don't tie it to 5V by accident! For that reason, we suggest going with the solder-jumper route.

Wiring

Wiring up the display in SPI mode is much easier than 8-bit mode since there's way fewer wires. Start by connecting the power pins

  • 3-5V Vin connects to the Arduino 5V pin
  • GND connects to Arduino ground
  • CLK connects to SPI clock. On Arduino Uno/Duemilanove/328-based, thats Digital 13. On Mega's, its Digital 52 and on Leonardo/Due its ICSP-3 (See SPI Connections for more details)
  • MISO connects to SPI MISO. On Arduino Uno/Duemilanove/328-based, thats Digital 12. On Mega's, its Digital 50 and on Leonardo/Due its ICSP-1 (See SPI Connections for more details)
  • MOSI connects to SPI MOSI. On Arduino Uno/Duemilanove/328-based, thats Digital 11. On Mega's, its Digital 51 and on Leonardo/Due its ICSP-4 (See SPI Connections for more details)
  • CS connects to our SPI Chip Select pin. We'll be using Digital 10 but you can later change this to any pin
  • D/C connects to our SPI data/command select pin. We'll be using Digital 9 but you can later change this pin too.

That's it! You do not need to connect the RST or other pins for now.

Install Arduino Libraries

We have example code ready to go for use with these TFTs. It's written for Arduino, which should be portable to any microcontroller by adapting the C++ source.

Three libraries need to be installed using the Arduino Library Manager…this is the preferred and modern way. From the Arduino “Sketch” menu, select “Include Library” then “Manage Libraries…”

Type “gfx” in the search field to quickly find the first library — Adafruit_GFX:

Repeat the search and install steps, looking for the Adafruit_ZeroDMA and Adafruit_HX8357 libraries.

After restarting the Arduino software, you should see a new example folder called Adafruit_HX8357 and inside, an example called graphicstest.

Upload the graphicstest sketch to your Arduino. You may need to press the Reset button to reset the Arduino and TFT. You should see a collection of graphical tests draw out on the TFT.

If you're having difficulties, check the serial console.The first thing the sketch does is read the driver configuration from the TFT, you should see the same numbers as below

If you did not connect up the MISO line to the TFT, you wont see the read configuation bytes so please make sure you connect up the MISO line for easy debugging! Once its all working, you can remove the MISO line

Bitmaps (SPI Mode)

There is a built in microSD card slot into the breakout, and we can use that to load bitmap images! You will need a microSD card formatted FAT16 or FAT32 (they almost always are by default).

Its really easy to draw bitmaps. However, this is only supported when talking to the display in SPI mode, not 8-bit mode!

Find the jumpers.bmp file in the downloaded Arduino library

Copy jumpers.bmp into the base directory of a microSD card and insert it into the microSD socket in the breakout.

You'll need to connect up the CCS pin to Digital 4 on your Arduino as well. See the image below

You may want to try the SD library examples before continuing, especially one that lists all the files on the SD card

Now upload the file->examples->Adafruit_HX8357->spitftbitmap example to your Arduino + breakout. You will see the jumper wires appear!

To make new bitmaps, make sure they are less than 320 by 480 pixels and save them in 24-bit BMP format! They must be in 24-bit format, even if they are not 24-bit color as that is the easiest format for the Arduino. You can rotate images using the setRotation() procedure

You can draw as many images as you want - dont forget the names must be less than 8 characters long. Just copy the BMP drawing routines below loop() and call

bmpDraw(bmpfilename, x, y);

For each bitmap. They can be smaller than 320x480 and placed in any location on the screen.

Adafruit GFX library

The Adafruit_GFX library for Arduino provides a common syntax and set of graphics functions for all of our TFT, LCD and OLED displays. This allows Arduino sketches to easily be adapted between display types with minimal fuss…and any new features, performance improvements and bug fixes will immediately apply across our complete offering of color displays.


The GFX library is what lets you draw points, lines, rectangles, round-rects, triangles, text, etc.

Check out our detailed tutorial here http://learn.adafruit.com/adafruit-gfx-graphics-library

It covers the latest and greatest of the GFX library. The GFX library is used in both 8-bit and SPI modes so the underlying commands (drawLine() for example) are identical!

Touchscreen

The LCD has a 3.5" 4-wire resistive touch screen glued onto it. You can use this for detecting finger-presses, stylus', etc. You'll need 4 pins to talk to the touch panel, and at least 2 must be analog inputs. The touch screen is a completely separate part from the TFT, so be aware if you rotate the display or have the TFT off or reset, the touch screen doesn't "know" about it - its just a couple resistors!

We have a demo for the touchscreen + TFT that lets you 'paint' simple graphics. There's versions for both SPI and 8-bit mode and are included in the libraries. Just make sure you have gone thru the TFT test procedure already since this builds on that.

Remember, if you rotate the screen drawing with setRotation() you'll have to use map() or similar to flip around the X/Y coordinates for the touchscreen as well! It doesn't know about drawing rotation

Download Library

Begin by grabbing our analog/resistive touchscreen library from github (or just click the download button)

Touchscreen Paint (SPI mode)

An additional 4 pins are required for the touchscreen. For the two analog pins, we'll use A2 and A3. For the other two connections, you can pin any two digital pins but we'll be using D8 and D7 since they are available.

Wire the additional 4 pins as follows:

  • Y+ to Arduino A2
  • X+ to Arduino D8
  • Y- to Arduino D7
  • X- to Arduino A3

Load up the breakoutTouchPaint example from the Adafruit_HX8357 library and try drawing with your fingernail! You can select colors by touching the 'pallette' of colors on the right

Touchscreen Paint (8-Bit mode)


Another 4 pins seems like a lot since already 12 are taken up with the TFT but you can reuse some of the pins for the TFT LCD! This is because the resistance of the panel is high enough that it doesn't interfere with the digital input/output and we can query the panel in between TFT accesses, when the pins are not being used.

We'll be building on the wiring used in the previous drawing test for UNO

You can wire up the 4 touchscreen pins as follows. Starting from the top

  • Y- connects to digital #9 (also D1)
  • The next one down (X-) connects to Analog 2 (also C/D)
  • The next one over (Y+) connects to Analog 3 (also CS)
  • The last one (X+) connects to digital 8. (also D0)

The X- and Y+ pins pretty much have to connect to those analog pins (or to analog 4/5) but Y-/X+ can connect to any digital or analog pins.

The image below shows the wiring, its for the 2.8" TFT but its the same wiring setup

Load up the tftpaint example from the Adafruit_TFTLCD library and try drawing with your fingernail! You can select colors by touching the 'pallette' of colors on the right

Troubleshooting

Display does not work on initial power but does work after a reset.

The display driver circuit needs a small amount of time to be ready after initial power. If your code tries to write to the display too soon, it may not be ready. It will work on reset since that typically does not cycle power. If you are having this issue, try adding a small amount of delay before trying to write to the display.

In Arduino, use delay() to add a few milliseconds before calling tft.begin(). Adjust the amount of delay as needed to see how little you can get away with for your specific setup.

Downloads

This guide was first published on Aug 19, 2014. It was last updated on Aug 19, 2014.