This is a library for the various AdaFruit TFT displays. Their webpage contains all the information on tutorials & wiring diagrams for the "classic" Arduino's. For SAMD21 variants, consult pin_magic.h. These displays use 8-bit parallel to communicate, 12 or 13 pins are required to interface (RST is optional).
Also requires the Adafruit_GFX library for Arduino. https://github.com/adafruit/Adafruit-GFX-Library
Fork code currently being pimped by Tim Jacobs / ThingTank to add support for the Arduino Zero (Pro) / SparkFun SAMD21 Dev Breakout, the Adafruit Feather M0 / Arduino MKR1000 devices, or any other device running a SAMD21 processor. I'm using the AdaFruit 2.8" TFT CapTouch board for testing.
Work is still in progress - library not completed yet - use at your own risk!
I've also added code that should make this library portable to other Arduino devices, not supported by AdaFruit. That code uses the standard Arduino communication (digitalRead, digitalWrite, ...) so is much slower compared to the optimized AdaFruit code for supported devices. You're probably better of using the SPI variation of the TFT LCD's in that case, but hey, the code is there if you need it.
I've also taken the liberty of merging in this fork the various pull requests that have been open for quite some time already in the main AdaFruit repository, specifically:
- Pull #27: The negative X1 coordinate bug
- Pull #24: Reset signal bugfix; readPixel() support for ILI9341
- Pull #17: Various fixes, most notabily a speed increase for drawing lines, compile-time screen mirroring support, etc...
The other open pull requests over at AdaFruit also all make sense, but where not applicable in my situation so didn't implement them (yet).
Speed benchmark in microseconds, using the "GraphicsTest" example, on different SAMD21 boards; SPI test performed on a Feather M0 Proto board=
| Test | Generic code | MKR1000 | Zero | SPI Test |
|---|---|---|---|---|
| Screen fill | 8.799.787 | 2.876.835 | 576.785 | 2.911.460 |
| Text | 937.758 | 467.650 | 271.590 | 211.796 |
| Lines | 8.669.701 | 4.558.891 | 2.867.372 | 2.051.591 |
| Horiz/Vert Lines | 1.093.055 | 400.925 | 83.923 | 241.689 |
| Rectangles (outline) | 716.133 | 267.931 | 63.451 | 156.215 |
| Rectangles (filled) | 26.619.628 | 9.795.900 | 1.800.202 | 6.046.101 |
| Circles (filled) | 5.139.809 | 2.182.144 | 877.089 | 995.220 |
| Circles (outline) | 3.785.683 | 1.992.094 | 1.251.726 | 894.614 |
| Triangles (outline) | 2.755.664 | 1.445.209 | 909.307 | 650.532 |
| Triangles (filled) | 9.542.007 | 3.632.513 | 942.129 | 2.060.690 |
| Rounded rects (outline) | 1.641.708 | 779.013 | 412.223 | 377.220 |
| Rounded rects (filled) | 29.925.709 | 10.835.993 | 2.155.870 | 6.639.757 |
The big difference between the "mini" SAMD21 boards like the MKR1000/AdaFruit Feather M0 and the bigger brothers Arduino Zero/Sparkfun SAMD21 Dev is that the design of the mini boards is compact, not exposing all the datapins of the SAMD21 processor - that is not necessarily a bad thing, just to be clear :). The bigger boards do expose all pins, which allows us to use some tricks in bit-shifting since we can neatly line up all 8 communication bits (saving on a dozen of operations per read & write operation to the TFT screen).
You'll quickly realize when working with an Arduino MKR1000 or AdaFruit Feather M0 that the TFT display in 8-bit parallel mode pretty much takes up every pin you have available on the breakout board. Nonetheless, we have a use case where we want to connect these LCDs to the more modern SAMD processors of Atmel like on the MKR1000 and AdaFruit Feather M0 board.
On top, there are other boards available with the SAMD21 that expose more pins (have a look at the SparkFun SAMD21 Dev Breakout, which has 5 more digital pins available). So for everybody trying to get one of the AdaFruit LCD's working on those boards, here is a good place to get started.
Added code for the "bigger brother" boards that allow to do some bitshifting tricks, providing an additional factor 5-6x speed increase compared to the previous optimizations. We're now roughly 10x faster than the generic code, using the standard Arduino functions. You must use the pin layouts below in order to get that working.
The following PIN connections are coded into pin_magic.h. You need to uncomment the appropriate pin config for your specific SAMD21 board in order to get the library working. If your board is not listed, you can use a more generic SAMD21 config (customize your pin layout), and if your board is totally not a SAMD21 board but something else, you can use the "Arduino Generic" code and pin layout. The latter is entirely customizable to however you want to wire your TFT screen.
| TFT Pin | MKR1000 | Arduino Zero |
|---|---|---|
| D0 | A4 | D2 |
| D1 | D12 | D5 |
| D2 | D11 | D11 |
| D3 | D10 | D13 |
| D4 | D9 | D10 |
| D5 | D6 | D12 |
| D6 | D5 | D6 |
| D7 | A5 | D7 |
| RD | A0 | A0 |
| WR | A1 | A1 |
| C/D | A2 | A2 |
| CS | A3 | A3 |
| RESET | Not connected | A4 |
Equivalent boards:
- MKR1000 pin layout also works on: AdaFruit Feather M0
- Arduino Zero pin layout also works on: Sparkfun SAMD21
- Generic SAMD21 pin layout: same as MKR1000 pin layout
- Generic pin layout: customize in
pin_magic.h
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Originally written by Limor Fried/Ladyada for Adafruit Industries.
Original credits: see readme.txt