60 lines
1.9 KiB
C
60 lines
1.9 KiB
C
/* Copyright 2020 Dimitris Papavasiliou <dpapavas@protonmail.ch>
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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 3 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 <https://www.gnu.org/licenses/>.
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*/
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#include <LUFA/Drivers/USB/USB.h>
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#include "lagrange.h"
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#ifndef SPLIT_USB_TIMEOUT_POLL
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# define SPLIT_USB_TIMEOUT_POLL 10
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#endif
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/* Instead of timing out, the slave waits indefinitely for the other
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* side to signal that it has become master. This avoids both sides
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* assuming the slave role when the USB port is powered but not
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* otherwise active (e.g. when the host is turned off, or suspended).
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* The SPI SS line is used for signaling. On power-up it is
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* configured as input with pull-up enabled. When one side assumes
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* the master role, it reconfigures the line for SPI, and pulls it low
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* to select the slave, which doubles as the signal. */
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bool is_keyboard_master(void) {
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static int8_t is_master = -1;
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if (is_master < 0) {
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while (readPin(SPI_SS_PIN)) {
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if (USB_Device_IsAddressSet()) {
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is_master = 1;
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return is_master;
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}
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wait_ms(SPLIT_USB_TIMEOUT_POLL);
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}
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is_master = 0;
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USB_Disable();
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USB_DeviceState = DEVICE_STATE_Unattached;
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}
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return is_master;
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}
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void keyboard_pre_init_kb(void) {
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setPinInputHigh(SPI_SS_PIN);
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keyboard_pre_init_user();
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}
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