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176 lines
4.8 KiB
176 lines
4.8 KiB
/* Copyright 2021 Jay Greco
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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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/*
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Remote keyboard is an experimental feature that allows for connecting another
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keyboard, macropad, numpad, or accessory without requiring an additional USB connection.
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The "remote keyboard" forwards its keystrokes using UART serial over TRRS. Dynamic VUSB
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detect allows the keyboard automatically switch to host or remote mode depending on
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which is connected to the USB port.
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Possible functionality includes the ability to send data from the host to the remote using
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a reverse link, allowing for LED sync, configuration, and more data sharing between devices.
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This will require a new communication protocol, as the current one is limited.
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*/
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#include "remote_kb.h"
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#include "uart.h"
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uint8_t
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msg[UART_MSG_LEN],
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msg_idx = 0;
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bool
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is_host = true;
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// Private functions
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static bool vbus_detect(void) {
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#if defined(__AVR_ATmega32U4__)
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//returns true if VBUS is present, false otherwise.
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USBCON |= (1 << OTGPADE); //enables VBUS pad
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_delay_us(10);
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return (USBSTA & (1<<VBUS)); //checks state of VBUS
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#else
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#error vbus_detect is not implemented for this architecure!
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#endif
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}
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static uint8_t chksum8(const unsigned char *buf, size_t len) {
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unsigned int sum;
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for (sum = 0 ; len != 0 ; len--)
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sum += *(buf++);
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return (uint8_t)sum;
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}
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static void send_msg(uint16_t keycode, bool pressed) {
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msg[IDX_PREAMBLE] = UART_PREAMBLE;
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msg[IDX_KCLSB] = (keycode & 0xFF);
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msg[IDX_KCMSB] = (keycode >> 8) & 0xFF;
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msg[IDX_PRESSED] = pressed;
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msg[IDX_CHECKSUM] = chksum8(msg, UART_MSG_LEN-1);
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uart_transmit(msg, UART_MSG_LEN);
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}
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static void print_message_buffer(void) {
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for (int i=0; i<UART_MSG_LEN; i++) {
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dprintf("msg[%u]: %u\n", i, msg[i]);
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}
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}
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static void process_uart(void) {
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uint8_t chksum = chksum8(msg, UART_MSG_LEN-1);
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if (msg[IDX_PREAMBLE] != UART_PREAMBLE || msg[IDX_CHECKSUM] != chksum) {
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dprintf("UART checksum mismatch!\n");
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print_message_buffer();
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dprintf("calc checksum: %u\n", chksum);
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} else {
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uint16_t keycode = (uint16_t)msg[IDX_KCLSB] | ((uint16_t)msg[IDX_KCMSB] << 8);
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bool pressed = (bool)msg[IDX_PRESSED];
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if (IS_RM_KC(keycode)) {
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keyrecord_t record;
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record.event.pressed = pressed;
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if (pressed) dprintf("Remote macro: press [%u]\n", keycode);
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else dprintf("Remote macro: release [%u]\n", keycode);
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process_record_user(keycode, &record);
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} else {
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if (pressed) {
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dprintf("Remote: press [%u]\n", keycode);
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register_code(keycode);
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} else {
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dprintf("Remote: release [%u]\n", keycode);
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unregister_code(keycode);
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}
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}
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}
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}
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static void get_msg(void) {
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while (uart_available()) {
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msg[msg_idx] = uart_read();
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dprintf("idx: %u, recv: %u\n", msg_idx, msg[msg_idx]);
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if (msg_idx == 0 && (msg[msg_idx] != UART_PREAMBLE)) {
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dprintf("Byte sync error!\n");
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msg_idx = 0;
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} else if (msg_idx == (UART_MSG_LEN-1)) {
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process_uart();
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msg_idx = 0;
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} else {
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msg_idx++;
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}
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}
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}
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static void handle_host_incoming(void) {
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get_msg();
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}
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static void handle_host_outgoing(void) {
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// for future reverse link use
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}
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static void handle_remote_incoming(void) {
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// for future reverse link use
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}
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static void handle_remote_outgoing(uint16_t keycode, keyrecord_t *record) {
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if (IS_HID_KC(keycode) || IS_RM_KC(keycode)) {
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dprintf("Remote: send [%u]\n", keycode);
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send_msg(keycode, record->event.pressed);
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}
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}
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// Public functions
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void matrix_init_remote_kb(void) {
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uart_init(SERIAL_UART_BAUD);
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is_host = vbus_detect();
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}
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void process_record_remote_kb(uint16_t keycode, keyrecord_t *record) {
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#if defined (KEYBOARD_HOST)
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handle_host_outgoing();
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#elif defined(KEYBOARD_REMOTE)
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handle_remote_outgoing(keycode, record);
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#else //auto check with VBUS
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if (is_host) {
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handle_host_outgoing();
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}
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else {
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handle_remote_outgoing(keycode, record);
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}
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#endif
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}
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void matrix_scan_remote_kb(void) {
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#if defined(KEYBOARD_HOST)
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handle_host_incoming();
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#elif defined (KEYBOARD_REMOTE)
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handle_remote_incoming();
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#else //auto check with VBUS
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if (is_host) {
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handle_host_incoming();
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}
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else {
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handle_remote_incoming();
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}
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#endif
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}
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