/* Copyright 2020 QMK * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include "kint41.h" #define LED_POWER LINE_PIN13 void matrix_init_kb(void) { matrix_init_user(); // Turn on the Teensy 4.x Power LED: setPinOutput(LED_POWER); writePinHigh(LED_POWER); } // delay_inline sleeps for |cycles| (e.g. sleeping for F_CPU will sleep 1s). // delay_inline assumes the cycle counter has already been initialized and // should not be modified, i.e. it is safe to call during keyboard matrix scan. // // ChibiOS enables the cycle counter in chcore_v7m.c: // https://github.com/ChibiOS/ChibiOS/blob/b63023915c304092acb9f33bbab40f3ec07a7f0e/os/common/ports/ARMCMx/chcore_v7m.c#L263 static void delay_inline(const uint32_t cycles) { const uint32_t start = DWT->CYCCNT; while ((DWT->CYCCNT - start) < cycles) { // busy-loop until time has passed } } void matrix_output_unselect_delay(uint8_t line, bool key_pressed) { // Use the cycle counter to do precise timing in microseconds. The ChibiOS // thread sleep functions only allow sleep durations starting at 1 tick, which // is 100μs in our configuration. // Empirically: e.g. 5μs is not enough, will result in keys that don’t work // and ghost key presses. 10μs seems to work well. // 600 cycles at 0.6 cycles/ns == 1μs const uint32_t cycles_per_us = 600; delay_inline(10 * cycles_per_us); }