quack/main/adb.c

/*
 *  adb.c
 *  quack
 *
 *  Created by Michel DEPEIGE on 7/01/2020.
 *  Copyright (c) 2020 Michel DEPEIGE.
 *
 * 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, 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 (see the file COPYING); if not, write to the
 * Free Software Foundation, Inc.,
 * 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA
 *
 */

#include <stdio.h>
#include "driver/gpio.h"
#include "sdkconfig.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_system.h"
#include "esp_spi_flash.h"

#include "adb.h"
#include "led.h"
#include "gpio.h"

extern TaskHandle_t t_green, t_blue, t_yellow, t_red;

/* static defines */
static uint16_t	adb_rx_mouse();
static bool adb_rx_tlt(void);
static void adb_tx_as(void);
static void	adb_tx_one(void);
static void	adb_tx_zero(void);

/* functions */

void	adb_init(void) {
	/* initialise */
	gpio_set_level(GPIO_ADB, 1);
	adb_tx_reset();

	/* If jumper is set, switch to ADB host mode */
	if (gpio_get_level(GPIO_ADBSRC) == 0)
		xTaskCreatePinnedToCore(&adb_task_host, "ADB_HOST", 6 * 1024, NULL, 4, NULL, 1);
	else
		xTaskCreatePinnedToCore(&adb_task_mouse, "ADB_MOUSE", 6 * 1024, NULL, 4, NULL, 1);
}

void	adb_task_host(void *pvParameters) {
	uint16_t	data;

	if (gpio_get_level(GPIO_BTOFF) == 0)
		xTaskNotify(t_green, LED_ON, eSetValueWithOverwrite);

	/* poll the mouse like a maniac. It will answer only if there is user input */
	while (1) {
		vTaskDelay(20 / portTICK_PERIOD_MS);
		adb_tx_cmd(ADB_MOUSE|ADB_TALK|ADB_REG0);

		if (adb_rx_tlt()) {
			data = adb_rx_mouse();
			xTaskNotify(t_yellow, LED_ONCE, eSetValueWithOverwrite);
		}
	}
}

void	adb_task_mouse(void *pvParameters) {

}

static uint16_t	adb_rx_mouse() {
	return 0;
}

static inline bool	adb_rx_tlt() {
	/*
	 * Stop-to-start time aka Tlt in some docs. This is called after a command packet
	 * The start bit has to appear between 140µs and 260µs
	 *
	 * return flase if no start bit detected
	 * return true if start bit detected
	 */

	char	i;

	/* wait 130µs then start polling */
	ets_delay_us(130);

	for (i = 0; i < 130; i++) {
		if (gpio_get_level(GPIO_ADB) == 0) {
			/* start bit found. wait for the end of it */
			ets_delay_us(99-2);
			return true;
		}
		ets_delay_us(1);
	}

	/*
	 * actually we wait more than 260µs because calling ets_delay_us takes
	 * a little more than 1µs to call. Depending on scheduling, the wait times is
	 * between 390µS and 650µs which is way past specs.
	 */

	return false;
}

static inline void	adb_tx_as() {
	/* send attention (800 µs low) + sync (70 µs high) */
	gpio_set_level(GPIO_ADB, 0);
	ets_delay_us(800-1);
	gpio_set_level(GPIO_ADB, 1);
	ets_delay_us(80-1);
}

void	adb_tx_cmd(unsigned char cmd) {
	gpio_set_direction(GPIO_ADB, GPIO_MODE_OUTPUT);
	adb_tx_as();

	/* send actual byte (unrolled loop) */
	cmd & 0x80 ? adb_tx_one() : adb_tx_zero();
	cmd & 0x40 ? adb_tx_one() : adb_tx_zero();
	cmd & 0x20 ? adb_tx_one() : adb_tx_zero();
	cmd & 0x10 ? adb_tx_one() : adb_tx_zero();
	cmd & 0x08 ? adb_tx_one() : adb_tx_zero();
	cmd & 0x04 ? adb_tx_one() : adb_tx_zero();
	cmd & 0x02 ? adb_tx_one() : adb_tx_zero();
	cmd & 0x01 ? adb_tx_one() : adb_tx_zero();

	/* stop bit */
	adb_tx_zero();
	gpio_set_direction(GPIO_ADB, GPIO_MODE_INPUT);
}

static inline void	adb_tx_one() {
	/* values from AN591 Datasheet minus the estimated call to ets_delay_us */
	gpio_set_level(GPIO_ADB, 0);
	ets_delay_us(35-1);
	gpio_set_level(GPIO_ADB, 1);
	ets_delay_us(65-1);
}

void	adb_tx_reset() {
	/*
	 * ADB spec says reset signal low for 3ms ±30%
	 * Note that the ADB Desktop Bus Mouse G5431 uses 4ms when plugged
	 * ADB mouse init in <70ms, but lets wait 500ms to be sure
	 */

	gpio_set_level(GPIO_ADB, 0);
	ets_delay_us(3000);
	gpio_set_level(GPIO_ADB, 1);
	ets_delay_us(500);
}

static inline void	adb_tx_zero() {
	/* values from AN591 Datasheet minus the estimated call to ets_delay_us */
	gpio_set_level(GPIO_ADB, 0);
	ets_delay_us(65-1);
	gpio_set_level(GPIO_ADB, 1);
	ets_delay_us(35-1);
}