This is an implementation of (yet another) Adafruit ILI9341 SPI lcd library for STM32duino official STM core and libmaple (roger's and steve's mainly F4) core.
This version use various hardware features on STM32 F1xx (Cortex M3) and F4xx (Cortex M4). In particular, this library uses the Arduino SPI (like) interface, in SPI.h and SPI.c bundled in the respective cores. It uses hardware SPI provided by the API and where available DMA. In addition, it uses bit banding that maps gpio register bits to memory locations.
When tested on STM32F401ccu 'blackpill' board, observed about 40%-50% performance improvements on steve's libmaple F4 core vs say the Adafruit original libraries. However, the use of all these hardware features means that this library is mcu (e.g. STM32 F1xx (Cortex M3) and F4xx (Cortex M4), etc) and core specific. The Adafruit's implementation is still a good library nevertheless and is pretty optimised as well for SPI TFT LCD and uses standard SPI interfaces.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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note that the instructions here assumes familiarity with stm32duino libmaple and/or STM official core and the sketch firmware install methods (e.g. using st-link, serial etc) STM32duino official core wiki STM32duino (roger's) libmaple core wiki STM32duino forum
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In addition it also assumes familiarity with the ILI9341 lcd modules e.g. 2.2inch SPI Module ILI9341
Adafruit ILI9341 lcd tutorial <- note this library is just for the graphics display, 'touch' handling isn't part of this. And this uses the SPI interface. -
note that the (libmaple roger's and steve's) core is a community core/effort and the official STM core is continually being improved. Hence things are always in flux including if those repositories and this would conntinue to exist, or if the codes would stay the way it is when this sketch/implementation is developed. there is no assurance if things would continue to work when you try this out
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the core needs to be STM32duino libmaple core or STM32duino official STM core
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using ILI9341 lcds with SPI requires 6 gpio pins. The SPI pins has to go to the hardware SPI pins (normally SPI1 default). check the mcu spec sheets on ST's web (e.g. stm32f103c8 stm32f401cc ) and board pins:
- MOSI - for SPI
- MISO - for SPI
- SCK - for SPI
- CS pin - chip select
- DC pin - command / data control pin
- RST pin - LCD reset pin
You can connect an additional (gpio) pin to the backlight pin on the LCD module. However , do check that there is some resistance of a few hundred ohms at the LCD backlight pin. Accordingly, it goes to a resistor to transistor (base) there driving the backlight, but it is better to be careful so as not to short out mcu pins. SPI uses the default SPI in the core (e.g. SPI1).
the mappings in graphics test sketch is as follows
#define TFT_CS PA4
#define TFT_CLK PA5
#define TFT_MISO PA6
#define TFT_MOSI PA7
#define TFT_RST PB0
#define TFT_DC PB1
#define BACKLIGHT PB10
- A preferred way to build/test this out is to copy the following into a sketch folder and build from there. That would build with the bundled graphicstest.
- Adafruit_GFX.cpp
- Adafruit_GFX.h
- Adafruit_ILI9341_STM.h
- Adafruit_ILI9341_STM.cpp
- glcdfont.c
- gfxfont.h
- graphicstest.ino
In addition you need to include "SPI.h" and SPI library (SPI.h, SPI.cpp) from the library path.
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the graphics test sketch pauses for a keypress on the serial monitor (usb serial) before starting. It responds to some single key commands.
pressing 's' pauses at the current test.
Once paused it responds to the following key commands '00' to '11' runs the particular test.
'i' in paused mode runs tft.begin() and reinitialise the lcd and start tests. -
To use this library in your sketch
#include "Adafruit_GFX.h"
#include "Adafruit_ILI9341_STM.h"
#include <SPI.h>
#define TFT_CS PA4
#define TFT_CLK PA5
#define TFT_MISO PA6
#define TFT_MOSI PA7
#define TFT_RST PB0
#define TFT_DC PB1
#define BACKLIGHT PB10
// This use hardware SPI and the above pins for CS/DC and lcd reset pin
// the LCD reset pin is important, the display often can't initialise if
// lcd reset pin is not setup or connected correctly
Adafruit_ILI9341_STM tft = Adafruit_ILI9341_STM(TFT_CS, TFT_DC, TFT_RST);
tft.begin();
...
for the rest you may like to review the graphicstest sketch example.
While the graphicstest sketch runs, it should display some values read from the registers. e.g.
ILI9341 Test!
Display Power Mode: 0x9C
MADCTL Mode: 0x48
Pixel Format: 0x5
Image Format: 0x9C
Self Diagnostic: 0xC0
Display id: 0x0,0,0
Display status: 0x29,82,0,0,0
if these values are zeros. check your assignment of the lcd reset pin and that the reset pin is well connected. if the display remain blank afterwards, check all other pins as well. if the display is dark connect a 3.3v, or 5v to the lcd backlight pin, but check that there is a series resistance at the pin or connect one say 300 ohms.
Sample run on STM32F401ccu black pill board running steve's libmaple F4 core
some results:
| Benchmark (microseconds) | Adafruit stm32f401ccu libmaple | this stm32f401ccu libmaple | this stm32f401ccu STM | this stm32f103c libmaple |
|---|---|---|---|---|
| Screen fill | 476799 | 154214 | 281883 | 218151 |
| Text | 41574 | 28952 | 64955 | 46689 |
| Lines | 352653 | 178780 | 422315 | 271537 |
| Horiz/Vert Lines | 41711 | 16029 | 28396 | 20380 |
| Rectangles (outline) | 26464 | 11457 | 21453 | 15329 |
| Rectangles (filled) | 990327 | 321118 | 596881 | 453655 |
| Circles (filled) | 138760 | 96610 | 209908 | 133400 |
| Circles (outline) | 156673 | 105746 | 262480 | 185020 |
| Triangles (outline) | 79426 | 49149 | 114021 | 69658 |
| Triangles (filled) | 339544 | 160997 | 309810 | 218832 |
| sum | 2643931 | 1123052 | 2312102 | 1632651 |
header legend
- first word. e.g. Adafruit is the lib used, 'this' is this lib
- 2nd word: stm32f401ccu stm32f103c is the mcu and board
- 3rd word: is the core STM, libmaple
Note that this probably isn't the most 'optimized', but that an attempt is to only use the SPI.h interfaces. This in part to allow codes to be used across the cores, keeping much of the codes common. reducing the if-defs. The use of hardware SPI and bit banding still helps with the STM core, though it isn't too obvious in the above stats. The Adafruit stats on libmaple core isn't directly comparable to STM core as it is different.
- This is 'alpha' software for now as it is pretty 'new' and 'unused'. So it may be 'broken' as you try this out. It may be upgraded to 'beta' at some point and it'd stay that way. things are always in flux and it is uncertain how far it'd remain that way.
- some 'corners' are cut, e.g. that additional SPI.beginTransaction() calls are not done in favor of a minor improvement in speeds. This could break, e.g. SPI in an inconsistent state if multiple SPI pheriperials are used.
- This library may not work on many core / mcu combinations. the board is normally irrelevant but listed as a reference. current known working combinations:
| core | mcu | freq | board |
|---|---|---|---|
| libmaple (rogers's, steve's) | stm32f401ccu | 84mhz | blackpill |
| libmaple (rogers's, steve's) | stm32f103c{8,b} | 72mhz | maple mini clone |
| STM official | stm32f401ccu | 84mhz | blackpill |
This implementation is brought to you by Andrew Goh.
Many thanks goes to Adafruit for the Adafruit GFX library. this library (the contained Adafruit_ILI9341_STM.h and Adafruit_ILI9341_STM.cpp) is based on Adafruit GFX. A copy of Adafruit GFX library is bundled with this library as libraries tend to be updated over time and may break compatibility. However, that means this copy may be outdated over time and do not benefit to fixes, improvements made in the original Adafruit GFX library.
And the various individuals Fedreric who maintain the Official (stm32duino) STM core and, Roger, Steve, and many others et.al for the community libmaple core. it is a very impressive community effort with no big 'company' behind it. all that made from comunity contributions (including this implementation) that literally made this possible.
- Adafruit GFX library.
- STM32duino official STM core
- STM32duino (roger's) libmaple core github note that this core contains the F4 implementation from steve as well. Hence, you could simply use this.
- STM32duino libmaple core - steve's repository github
- leaflabs libjmaple - the 'oldest' origin
- STM32duino forum
- STM32duino (roger's) libmaple core wiki
- STM32duino official core
- STM32duino official core wiki
- arduino IDE
developing this has taken quite some effort mainly in getting it to work across the cores, optimizations and some tests.
if you use this codes and found it useful, i'd really appreciate it if you could support my efforts 
;)