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README.md	dedicated gpio: matrix keyboard example	2020-10-20 21:06:10 +08:00

README.md

Supported Targets	ESP32-S2

Matrix Keyboard Example (based on Dedicated GPIO)

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

Overview

This example mainly illustrates how to drive a common matrix keyboard using the dedicated GPIO APIs, including:

Manipulate the level on a group of GPIOs
Trigger edge interrupt
Read level on a group of GPIOs

Dedicated GPIO is designed to speed up CPU operations on one or a group of GPIOs by writing assembly codes with Espressif customized instructions (please refer TRM to get more information about these instructions).

This matrix keyboard driver is interrupt-driven, supports a configurable debounce time. GPIOs used by row and column lines are also configurable during driver installation stage.

How to use example

Hardware Required

This example can run on any target that has the dedicated feature (e.g. ESP32-S2). It's not necessary for your matrix board to have pull-up resisters on row/column lines. The driver has enabled internal pull-up resister by default. A typical matrix board should look as follows:

row_0   +--------+-------------------+------------------------------+-----------------+
                 |                   |                              |
                 |       +           |       +                      |       +
                 |     +-+-+         |     +-+-+          ......    |     +-+-+
  .              +-----+   +-----+   +-----+   +-----+              +-----+   +-----+
  .                              |                   |                              |
  .                      .       |           .       |                      .       |
                         .       |           .       |    ......            .       |
                         .       |           .       |                      .       |
                         .       |           .       |                      .       |
                                 |                   |                              |
row_n   +--------+-------------------+------------------------------+-----------------+
                 |               |   |               |              |               |
                 |       +       |   |       +       |              |       +       |
                 |     +-+-+     |   |     +-+-+     |    ......    |     +-+-+     |
                 +-----+   +-----+   +-----+   +-----+              +-----+   +-----+
                                 |                   |                              |
                                 |                   |                              |
                                 |                   |                              |
                                 +                   +                              +
                                col_0               col_1          ......          col_m

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

idf.py -p PORT flash monitor

(Replace PORT with the name of the serial port to use.)

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

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

Example Output

I (2883) example: press event, key code = 0002
I (3003) example: release event, key code = 0002
I (5053) example: press event, key code = 0001
I (5203) example: release event, key code = 0001
I (6413) example: press event, key code = 0000
I (6583) example: release event, key code = 0000
I (7963) example: press event, key code = 0003
I (8113) example: release event, key code = 0003
I (8773) example: press event, key code = 0103
I (8923) example: release event, key code = 0103
I (9543) example: press event, key code = 0203
I (9683) example: release event, key code = 0203