57 lines
2.1 KiB
C
57 lines
2.1 KiB
C
/* 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 "quantum.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.
|
||
|
||
// On some variants of the hardware, 20μs seems to be required. This was found
|
||
// on a combination of KB600LF+stapelberg v2020-06-30+teensy41.
|
||
|
||
// 600 cycles at 0.6 cycles/ns == 1μs
|
||
const uint32_t cycles_per_us = 600;
|
||
delay_inline(20 * cycles_per_us);
|
||
}
|