102 lines
2.9 KiB
C
102 lines
2.9 KiB
C
/* Copyright 2022
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "matrix.h"
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#include "gpio.h"
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#include "sn74x154.h"
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static const pin_t row_pins[MATRIX_ROWS] = MATRIX_ROW_PINS;
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/* All columns use a 74HC154 4-to-16 demultiplexer.
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* D3 is the enable pin, must be set high to use it.
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*
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* A3 A2 A1 A0
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* D7 D6 D5 D4
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* 0: 0 0 0 0
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* 1: 0 0 0 1
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* 2: 0 0 1 0
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* 3: 0 0 1 1
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* 4: 0 1 0 0
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* 5: 0 1 0 1
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* 6: 0 1 1 0
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* 7: 0 1 1 1
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* 8: 1 0 0 0
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* 9: 1 0 0 1
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* 10: 1 0 1 0
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* 11: 1 0 1 1
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* 12: 1 1 0 0
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* 13: 1 1 0 1
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* 14: 1 1 1 0
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* 15: 1 1 1 1
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*/
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static void select_col(uint8_t col) {
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sn74x154_set_addr(col);
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}
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static void init_pins(void) {
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for (uint8_t x = 0; x < MATRIX_ROWS; x++) {
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gpio_set_pin_input_high(row_pins[x]);
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}
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}
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static bool read_rows_on_col(matrix_row_t current_matrix[], uint8_t current_col) {
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bool matrix_changed = false;
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// Select col and wait for col seleciton to stabilize
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select_col(current_col);
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matrix_io_delay();
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// For each row...
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for (uint8_t row_index = 0; row_index < MATRIX_ROWS; row_index++) {
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// Store last value of row prior to reading
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matrix_row_t last_row_value = current_matrix[row_index];
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// Check row pin state
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if (gpio_read_pin(row_pins[row_index]) == 0) {
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// Pin LO, set col bit
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current_matrix[row_index] |= (MATRIX_ROW_SHIFTER << current_col);
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} else {
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// Pin HI, clear col bit
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current_matrix[row_index] &= ~(MATRIX_ROW_SHIFTER << current_col);
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}
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// Determine if the matrix changed state
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if ((last_row_value != current_matrix[row_index]) && !(matrix_changed)) {
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matrix_changed = true;
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}
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}
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return matrix_changed;
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}
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void matrix_init_custom(void) {
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// initialize demultiplexer
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sn74x154_init();
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sn74x154_set_enabled(true);
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// initialize key pins
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init_pins();
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}
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bool matrix_scan_custom(matrix_row_t current_matrix[]) {
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bool changed = false;
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// Set col, read rows
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for (uint8_t current_col = 0; current_col < MATRIX_COLS; current_col++) {
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changed |= read_rows_on_col(current_matrix, current_col);
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}
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return changed;
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}
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