esp-idf/examples/peripherals/gpio/matrix_keyboard/README.md

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| 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
```