esp-idf/examples/peripherals/lcd/tjpgd

LCD tjpgd example

(See the README.md file in the upper level 'examples' directory for more information about examples.)

Overview

This example shows how to decode a jpeg image and display it on an SPI-interfaced LCD, and rotates the image periodically.

Due to the fact that ESP32S2 and ESP32C3 don't have enough memory to hold the decoded image, the graphic shown on the LCD is calculated randomly and has nothing to do with the picture in the example project.

If you want to adapt this example to another type of display or pinout, check lcd_tjpgd_example_main.c for comments with some implementation details.

How to Use Example

Hardware Required

• An ESP development board
• An SPI-interfaced LCD
• An USB cable for power supply and programming

Hardware Connection

The connection between ESP Board and the LCD is as follows:

      ESP Board                            LCD Screen
      +---------+              +---------------------------------+
      |         |              |                                 |
      |     3V3 +--------------+ VCC   +----------------------+  |
      |         |              |       |                      |  |
      |     GND +--------------+ GND   |                      |  |
      |         |              |       |                      |  |
      |   DATA0 +--------------+ MOSI  |                      |  |
      |         |              |       |                      |  |
      |    PCLK +--------------+ SCK   |                      |  |
      |         |              |       |                      |  |
      |      CS +--------------+ CS    |                      |  |
      |         |              |       |                      |  |
      |     D/C +--------------+ D/C   |                      |  |
      |         |              |       |                      |  |
      |     RST +--------------+ RST   |                      |  |
      |         |              |       |                      |  |
      |BK_LIGHT +--------------+ BCKL  +----------------------+  |
      |         |              |                                 |
      +---------+              +---------------------------------+

The GPIO number used by this example can be changed in lcd_tjpgd_example_main.c, where:

GPIO number	LCD pin
EXAMPLE_PIN_NUM_PCLK	SCK
EXAMPLE_PIN_NUM_CS	CS
EXAMPLE_PIN_NUM_DC	DC
EXAMPLE_PIN_NUM_RST	RST
EXAMPLE_PIN_NUM_DATA0	MOSI
EXAMPLE_PIN_NUM_BK_LIGHT	BCKL

Especially, please pay attention to the level used to turn on the LCD backlight, some LCD module needs a low level to turn it on, while others take a high level. You can change the backlight level macro EXAMPLE_LCD_BK_LIGHT_ON_LEVEL in lcd_tjpgd_example_main.c.

Extra connections for 8-line LCD (Octal SPI)

Firstly, please run idf.py menuconfig and set the Drive a LCD with 8 data lines option at Example Configuration.

Change the extra GPOIs used by octal SPI in lcd_tjpgd_example_main.c, where:

GPIO number	LCD pin
PIN_NUM_DATA1	D1
PIN_NUM_DATA2	D2
PIN_NUM_DATA3	D3
PIN_NUM_DATA4	D4
PIN_NUM_DATA5	D5
PIN_NUM_DATA6	D6
PIN_NUM_DATA7	D7

Build and Flash

Run idf.py -p PORT flash monitor to build, flash and monitor the project. A flowing picture will be shown on the LCD screen.

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Troubleshooting

For any technical queries, please open an [issue] (https://github.com/espressif/esp-idf/issues) on GitHub. We will get back to you soon.