93 lines
2.6 KiB
C
93 lines
2.6 KiB
C
/*
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Copyright 2022 somepin
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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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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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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 "sn74x138.h"
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static const pin_t col_pins[MATRIX_COLS] = MATRIX_COL_PINS;
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/* All rows use a 74HC138 3 to 8 bit demultiplexer.
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*
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* A2 A1 A0
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* D0 D1 D2
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* 0: 0 0 0
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* 1: 0 0 1
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* 2: 0 1 0
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* 3: 0 1 1
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* 4: 1 0 0
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* 5: 1 0 1
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* 6: 1 1 0
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*/
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static void select_row(uint8_t row) {
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sn74x138_set_addr(row);
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}
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static void init_pins(void) {
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for (uint8_t x = 0; x < MATRIX_COLS; x++) {
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gpio_set_pin_input_high(col_pins[x]);
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}
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}
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static bool read_cols_on_row(matrix_row_t current_matrix[], uint8_t current_row) {
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bool matrix_changed = false;
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// Store last value of row prior to reading
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matrix_row_t last_row_value = current_matrix[current_row];
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// Start with a clear matrix row
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current_matrix[current_row] = 0;
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// Select row and wait for row selection to stabilize
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select_row(current_row);
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matrix_io_delay();
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// For each col...
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matrix_row_t row_shifter = MATRIX_ROW_SHIFTER;
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for (uint8_t col_index = 0; col_index < MATRIX_COLS; col_index++) {
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// Select the col pin to read (active low)
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uint8_t pin_state = gpio_read_pin(col_pins[col_index]);
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// Populate the matrix row with the state of the col pin
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current_matrix[current_row] |= pin_state ? 0 : (row_shifter << col_index);
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}
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// Determine if matrix changed state
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if ((last_row_value != current_matrix[current_row]) && !(matrix_changed)) {
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matrix_changed = true;
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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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sn74x138_init();
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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 row, read cols
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for (uint8_t current_row = 0; current_row < MATRIX_ROWS; current_row++) {
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changed |= read_cols_on_row(current_matrix, current_row);
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}
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return changed;
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}
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