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4 changes: 4 additions & 0 deletions CMakeLists.txt
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file(GLOB_RECURSE SOURCES src/*.c)
idf_component_register(SRCS ${SOURCES}
INCLUDE_DIRS "include"
REQUIRES driver freertos u8g2)
202 changes: 202 additions & 0 deletions LICENSE
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Copyright 2017 Neil Kolban
Copyright 2020 Markus Frey

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81 changes: 81 additions & 0 deletions README.md
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# U8g2 compatibility component for esp-idf on ESP32
## Note
This is effectively a fork of the U8G2 code that is part of Neil Kolban's excellent `esp32-snippets` repository. It can be found
[here](https://github.com/nkolban/esp32-snippets/tree/master/hardware/displays/U8G2).

His repository is no longer maintained and using a single directory as submodule is not possible. So I copied the relevant
files and made them a functional component for esp-idf by creating the required build system files.

This component should compile on both esp-idf version 3 and 4. It has been tested on 4.1.

## Description
There is an excellent open source library called `u8g2` that can be found on Github here:

[https://github.com/olikraus/u8g2](https://github.com/olikraus/u8g2)

The purpose of the library is to provide a display independent driver layer for monochrome displays including LCD and OLED.
The library "knows" how to driver the underlying displays as well as providing drawing primitives including text, fonts, lines and
other geometrical shapes.

A version of the library is available in cleanly compiling C and compiles without incident on the ESP32-IDF framework.

However, since the library is agnostic of MCU environments and will work on a variety of boards, there has to be a mapping from
the functions expected by the library to the underlying MCU board hardware. This includes driving GPIOs, I2C, SPI and more.

The code in this folder provides a mapping from U8g2 to the ESP32 ESP-IDF. This should be included in your build of U8g2 applications.

To use with the ESP32, we must invoke the `u8g2_esp32_hal_init()` function before invoking any of the normal U8g2 functons. What
this call does is tell the ESP32 what pins we wish to map. Here is an example of SPI use:

```
u8g2_esp32_hal_t u8g2_esp32_hal = U8G2_ESP32_HAL_DEFAULT;
u8g2_esp32_hal.clk = PIN_CLK;
u8g2_esp32_hal.mosi = PIN_MOSI;
u8g2_esp32_hal.cs = PIN_CS;
u8g2_esp32_hal.dc = PIN_DC;
u8g2_esp32_hal.reset = PIN_RESET;
u8g2_esp32_hal_init(u8g2_esp32_hal);
```

and here is an example of I2C use:

```
u8g2_esp32_hal_t u8g2_esp32_hal = U8G2_ESP32_HAL_DEFAULT;
u8g2_esp32_hal.sda = PIN_SDA;
u8g2_esp32_hal.scl = PIN_SCL;
u8g2_esp32_hal_init(u8g2_esp32_hal);
```

Note: For I2C, after calling the display specific setup, invoke:

```
u8x8_SetI2CAddress(&u8g2.u8x8,<address>);
```

Note that `<address>` is the I2C address already shifted left to include the read/write flag. For example, if you are using an SSD1305, instead of supplying the address `0x3C` which would be `0011 1100` supply `0x78` which would be `0111 1000`.

The function takes as input a `u8g2_esp32_hal` structure instance which has the logical pins that U8g2 needs mapped to the
physical pins on the ESP32 that we wish to use. If we don't use a specific pin for our specific display, set the value to
be `U8G2_ESP32_HAL_UNDEFINED` which is the default initialization value.

Remember, ESP32 pins are not hard-coded to functions and as such, all the GPIO pins on the ESP32 are open for use. Following
this initialization, we can use U8g2 as normal and described in the U8g2 documentation.

## Compiling U8G2
To use the actual U8g2 library in your ESP32 project, perform the following steps:

1. Create a directory called `components` in your main project directory.
2. Change into the `components` directory.
3. Run `git clone https://github.com/olikraus/u8g2.git` to bring in a the latest copy of u8g2 library.
4. Change into the `u8g2` directory.
5. Create a file called `component.mk`
6. Enter the following in the `component.mk` file:
```
COMPONENT_SRCDIRS:=csrc
COMPONENT_ADD_INCLUDEDIRS:=csrc
```


## Development
While in principal, there should be nothing specific needed beyond this addition to make U8g2 work on the ESP32, only a small
number of boards have been tested.
2 changes: 2 additions & 0 deletions component.mk
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COMPONENT_SRCDIRS:=src
COMPONENT_ADD_INCLUDEDIRS:=include
58 changes: 58 additions & 0 deletions examples/test_SSD1306.c
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#include <driver/gpio.h>
#include <driver/spi_master.h>
#include <esp_log.h>
#include <freertos/FreeRTOS.h>
#include <freertos/task.h>
#include <stdio.h>
#include <string.h>
#include <u8g2.h>

#include "sdkconfig.h"
#include "u8g2_esp32_hal.h"

// CLK - GPIO14
#define PIN_CLK 14

// MOSI - GPIO 13
#define PIN_MOSI 13

// RESET - GPIO 26
#define PIN_RESET 26

// DC - GPIO 27
#define PIN_DC 27

// CS - GPIO 15
#define PIN_CS 15
static char tag[] = "test_SSD1306";

void task_test_SSD1306(void *ignore) {
u8g2_esp32_hal_t u8g2_esp32_hal = U8G2_ESP32_HAL_DEFAULT;
u8g2_esp32_hal.clk = PIN_CLK;
u8g2_esp32_hal.mosi = PIN_MOSI;
u8g2_esp32_hal.cs = PIN_CS;
u8g2_esp32_hal.dc = PIN_DC;
u8g2_esp32_hal.reset = PIN_RESET;
u8g2_esp32_hal_init(u8g2_esp32_hal);


u8g2_t u8g2; // a structure which will contain all the data for one display
u8g2_Setup_ssd1306_128x64_noname_f(
&u8g2,
U8G2_R0,
u8g2_esp32_spi_byte_cb,
u8g2_esp32_gpio_and_delay_cb); // init u8g2 structure

u8g2_InitDisplay(&u8g2); // send init sequence to the display, display is in sleep mode after this,

u8g2_SetPowerSave(&u8g2, 0); // wake up display
u8g2_ClearBuffer(&u8g2);
u8g2_DrawBox(&u8g2, 10,20, 20, 30);
u8g2_SetFont(&u8g2, u8g2_font_ncenB14_tr);
u8g2_DrawStr(&u8g2, 0,15,"Hello World!");
u8g2_SendBuffer(&u8g2);

ESP_LOGD(tag, "All done!");

vTaskDelete(NULL);
}
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