- Generated on Fri Dec 20 2024 20:02:08 by
1.9.8
Matrix keypad driver for row/column keypads. More...
Matrix keypad driver for row/column keypads.
This module implements a simple matrix keypad driver where keys are connected between GPIO columns and rows. It works best with diodes in series with the switches to prevent key ghosting, but it can be used without these diodes. CONFIG_MATRIX_KEYPAD_ROWS_USE_OPEN_DRAIN can be enabled when the keypad doesn't use diodes in the switches.
The keypad works by configuring the column GPIOs as input with pull-ups. Each row is configured as open drain with pull-up. One by one the rows are set to pull their output low. For each row the column GPIOs are read and the state is checked. When a key is pressed the column GPIO of that switch will read low as soon as the row it is on is pulled low.
The debouncing algorithm is a pattern style debounce where the switch must be in one position for a number of samples, then a set of "don't care" samples and then in the other position for a number of samples. The samples in the middle allow for a period where the switch can be either low or high without affecting the transition. The exact pattern is determined by CONFIG_MATRIX_KEYPAD_DEBOUNCE_PATTERN_BEGIN and CONFIG_MATRIX_KEYPAD_DEBOUNCE_PATTERN_END. These are used as mask where the switch must be in a determined state. The bits where neither pattern is set is used as the "don't care" set of samples.
A full scan of the matrix keypad is done via the matrix_keypad_scan function. This function iterates over all rows and columns to update the stored history of every pin.
When a state change is detected on a switch, the matrix_keypad_cb_t callback is called with the row and column number together with the new state of the switch (pressed or not pressed).
Files | |
| file | matrix_keypad.h |
| Interface definition for the matrix keypad. | |
| file | matrix_keypad_params.h |
| Default configuration. | |
Data Structures | |
| struct | matrix_keypad_params_t |
| Device initialization parameters. More... | |
| struct | matrix_keypad_t |
| Device descriptor for the driver. More... | |
Macros | |
| #define | CONFIG_MATRIX_KEYPAD_NUM_ROWS 2 |
| Maximum number of rows. | |
| #define | CONFIG_MATRIX_KEYPAD_NUM_COLUMNS 2 |
| Maximum number of columns. | |
| #define | CONFIG_MATRIX_KEYPAD_DEBOUNCE_PATTERN_BEGIN 0xC0 |
| Debounce pattern high to low bits. | |
| #define | CONFIG_MATRIX_KEYPAD_DEBOUNCE_PATTERN_END 0x7 |
| Debounce pattern low to high bits. | |
| #define | CONFIG_MATRIX_KEYPAD_ROWS_USE_OPEN_DRAIN 0 |
| Use open drain GPIO mode. | |
| #define | MATRIX_KEYPAD_ROWS_GPIO_MODE GPIO_OUT |
| GPIO mode used for the row GPIOs. | |
| #define | MATRIX_KEYPAD_DEBOUNCE_MASK (CONFIG_MATRIX_KEYPAD_DEBOUNCE_PATTERN_BEGIN | CONFIG_MATRIX_KEYPAD_DEBOUNCE_PATTERN_END) |
| Debounce pattern mask. | |
Typedefs | |
| typedef uint8_t | matrix_keypad_state_row_t |
| Type definition for a full row (all columns) state, variable width depending on the number of columns. | |
| typedef void(* | matrix_keypad_cb_t) (void *arg, size_t row, size_t column, bool state) |
| Callback for key state changes. | |
Functions | |
| int | matrix_keypad_init (matrix_keypad_t *dev, const matrix_keypad_params_t *params, matrix_keypad_cb_t callback, void *arg) |
| Initialize the given device. | |
| size_t | matrix_keypad_scan (matrix_keypad_t *dev) |
| Scan through the keypad matrix. | |
| #define CONFIG_MATRIX_KEYPAD_DEBOUNCE_PATTERN_BEGIN 0xC0 |
Debounce pattern high to low bits.
This pattern should consist of bits set on the most significant bits of the value. The number of bits set determines the number of scans the key must be in the current state before a change is processed.
Definition at line 85 of file matrix_keypad.h.
| #define CONFIG_MATRIX_KEYPAD_DEBOUNCE_PATTERN_END 0x7 |
Debounce pattern low to high bits.
This pattern should consist of bits set on the least significant bits of the value. The number of bits set determines the number of scans the key must be in the next state before a change is processed.
Definition at line 96 of file matrix_keypad.h.
| #define CONFIG_MATRIX_KEYPAD_NUM_COLUMNS 2 |
Maximum number of columns.
Definition at line 74 of file matrix_keypad.h.
| #define CONFIG_MATRIX_KEYPAD_NUM_ROWS 2 |
Maximum number of rows.
Definition at line 67 of file matrix_keypad.h.
| #define CONFIG_MATRIX_KEYPAD_ROWS_USE_OPEN_DRAIN 0 |
Use open drain GPIO mode.
Definition at line 103 of file matrix_keypad.h.
| #define MATRIX_KEYPAD_DEBOUNCE_MASK (CONFIG_MATRIX_KEYPAD_DEBOUNCE_PATTERN_BEGIN | CONFIG_MATRIX_KEYPAD_DEBOUNCE_PATTERN_END) |
Debounce pattern mask.
Definition at line 118 of file matrix_keypad.h.
| #define MATRIX_KEYPAD_ROWS_GPIO_MODE GPIO_OUT |
GPIO mode used for the row GPIOs.
Definition at line 112 of file matrix_keypad.h.
| typedef void(* matrix_keypad_cb_t) (void *arg, size_t row, size_t column, bool state) |
Callback for key state changes.
| arg | callback context |
| row | Row that changed |
| column | Column that changed |
| state | New state of the key, 1 = pressed, 0 = released |
Definition at line 166 of file matrix_keypad.h.
| typedef uint8_t matrix_keypad_state_row_t |
Type definition for a full row (all columns) state, variable width depending on the number of columns.
Definition at line 126 of file matrix_keypad.h.
| int matrix_keypad_init | ( | matrix_keypad_t * | dev, |
| const matrix_keypad_params_t * | params, | ||
| matrix_keypad_cb_t | callback, | ||
| void * | arg | ||
| ) |
Initialize the given device.
| [in,out] | dev | Device descriptor of the driver |
| [in] | params | Initialization parameters |
| [in] | callback | Callback to call on state changes |
| [in] | arg | Context argument for the callback |
| size_t matrix_keypad_scan | ( | matrix_keypad_t * | dev | ) |
Scan through the keypad matrix.
This updates the state of the device descriptor, calling matrix_keypad_cb_t when a key press or release has been detected
| [in,out] | dev | Device descriptor of the driver |
1.9.8