stm32f1/application.c

/* 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 3 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/>.
 *
 */
/** CuVoodoo USB cable tester firmware
 *  @file
 *  @author King Kévin <kingkevin@cuvoodoo.info>
 *  @date 2016-2020
 */

/* standard libraries */
#include <stdint.h> // standard integer types
#include <stdlib.h> // standard utilities
#include <string.h> // string utilities
#include <time.h> // date/time utilities
#include <ctype.h> // utilities to check chars

/* STM32 (including CM3) libraries */
#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
#include <libopencm3/cm3/scb.h> // vector table definition
#include <libopencm3/cm3/nvic.h> // interrupt utilities
#include <libopencm3/stm32/gpio.h> // general purpose input output library
#include <libopencm3/stm32/rcc.h> // real-time control clock library
#include <libopencm3/stm32/exti.h> // external interrupt utilities
#include <libopencm3/stm32/rtc.h> // real time clock utilities
#include <libopencm3/stm32/iwdg.h> // independent watchdog utilities
#include <libopencm3/stm32/dbgmcu.h> // debug utilities
#include <libopencm3/stm32/desig.h> // design utilities
#include <libopencm3/stm32/flash.h> // flash utilities

/* own libraries */
#include "global.h" // board definitions
#include "print.h" // printing utilities
#include "usb_cdcacm.h" // USB CDC ACM utilities
#include "terminal.h" // handle the terminal interface
#include "menu.h" // menu utilities
#include "usb_cables.h" // USB cables definition

/** watchdog period in ms */
#define WATCHDOG_PERIOD 10000

/** set to 0 if the RTC is reset when the board is powered on, only indicates the uptime
 *  set to 1 if VBAT can keep the RTC running when the board is unpowered, indicating the date and time
 */
#define RTC_DATE_TIME 0

/** number of RTC ticks per second
 *  @note use integer divider of oscillator to keep second precision
 */
#define RTC_TICKS_SECOND 4

/** RTC time when device is started */
static time_t time_start = 0;

/** @defgroup main_flags flag set in interrupts to be processed in main task
 *  @{
 */
volatile bool rtc_internal_tick_flag = false; /**< flag set when internal RTC ticked */
/** @} */

size_t putc(char c)
{
	size_t length = 0; // number of characters printed
	static char last_c = 0; // to remember on which character we last sent
	if ('\n' == c) { // send carriage return (CR) + line feed (LF) newline for each LF
		if ('\r' != last_c) { // CR has not already been sent
			usb_cdcacm_putchar('\r'); // send CR over USB
			length++; // remember we printed 1 character
		}
	}
	usb_cdcacm_putchar(c); // send byte over USB
	length++; // remember we printed 1 character
	last_c = c; // remember last character
	return length; // return number of characters printed
}

/** put all pins of all connectors to float */
static void usb_pins_float(void)
{
	usb_cables_connectors_float(usb_connectors, LENGTH(usb_connectors)); // put every pin of every connector in floating mode
}

/** display available commands
 *  @param[in] argument no argument required
 */
static void command_help(void* argument);

/** show software and hardware version
 *  @param[in] argument no argument required
 */
static void command_version(void* argument);

/** show uptime
 *  @param[in] argument no argument required
 */
static void command_uptime(void* argument);

#if RTC_DATE_TIME
/** show date and time
 *  @param[in] argument date and time to set
 */
static void command_datetime(void* argument);
#endif

/** reset board
 *  @param[in] argument no argument required
 */
static void command_reset(void* argument);

/** switch to DFU bootloader
 *  @param[in] argument no argument required
 */
static void command_bootloader(void* argument);

/** test USB connectors intra-connections
 *  @param[in] argument no argument required
 */
static void command_intra(void* argument)
{
	(void)argument; // we won't use the argument

	usb_pins_float(); // start with all pins in safe floating state

	printf("= intra-connector check =\n");
	for (uint8_t connector = 0; connector < LENGTH(usb_connectors); connector++) { // test from every connector
		printf("- %s -\n", usb_connectors[connector]->name);
		usb_cables_check_intra(usb_connectors[connector], NULL);
	}

	usb_pins_float(); // put all pins back in safe floating state
}

/** test USB connectors inter-connections
 *  @param[in] argument no argument required
 */
static void command_inter(void* argument)
{
	(void)argument; // we won't use the argument

	usb_pins_float(); // start with all pins in safe floating state

	// step 1: find which connectors are connected
	printf("= inter-connector check =\n");
	usb_cables_check_inter(usb_connectors, LENGTH(usb_connectors), NULL);

	usb_pins_float(); // put all pins back in safe floating state
}

/** test USB cables
 *  @param[in] argument no argument required
 */
static void command_cables(void* argument)
{
	(void)argument; // we won't use the argument

	usb_pins_float(); // start with all pins in safe floating state

	// step 2: check for known cable configuration
	printf("= cable check =\n");
	for (uint8_t cable = 0; cable < LENGTH(usb_cables); cable++) { // test every cable
		uint8_t pair_defined, pair_undefined, pair_disconnected, pair_error;
		bool result = usb_cables_check_cable(&usb_cables[cable], &pair_defined, &pair_undefined, &pair_disconnected, &pair_error);
		printf("%s: %s (defined=%u, undefined=%u, disconnected=%u, error=%u)\n", result ? "OK" : "KO", usb_cables[cable].name, pair_defined, pair_undefined, pair_disconnected, pair_error);
	}

	usb_pins_float(); // put all pins back in safe floating state
}

/** find out which USB cable is connected
 *  @param[in] argument no argument required
 */
static void command_find(void* argument)
{
	(void)argument; // we won't use the argument

	printf("= cable finder =\n");
	usb_pins_float(); // start with all pins in safe floating state

	// figure out which connectors are used
	bool connected[LENGTH(usb_connectors)];
	usb_cables_check_inter(usb_connectors, LENGTH(usb_connectors), connected);
	uint8_t connected_nb = 0;
	printf("connectors:\n");
	for (uint8_t i = 0; i < LENGTH(connected); i++) {
		if (connected[i]) {
			printf("- %s (%s)\n", usb_connectors[i]->name, usb_connectors[i]->host ? "host" : "device");
			connected_nb++;
		}
	}

	// find matching cable
	uint8_t matches = 0; // number of matching cables
	printf("matching cables:\n");
	for (uint8_t cable = 0; cable < LENGTH(usb_cables); cable++) {
		// ensure we have the same number of connections as the cable
		if (usb_cables[cable].connectors_nb != connected_nb) {
			continue;
		}
		// ensure all the connectors we have are also in the cable
		bool match = true;
		for (uint8_t i = 0; i < LENGTH(usb_connectors) && match; i++) {
			if (!connected[i]) {
				continue;
			}
			bool found = false;
			for (uint8_t j = 0; j < usb_cables[cable].connectors_nb; j++) {
				if (usb_connectors[i] == usb_cables[cable].connectors[j]) {
					found = true;
				}
			}
			if (!found) {
				match = false;
			}
		}
		// ensure we also have all the connectors which are in the cable
		for (uint8_t i = 0; i < usb_cables[cable].connectors_nb && match; i++) {
			bool found = false;
			for (uint8_t j = 0; j < LENGTH(usb_connectors); j++) {
				if (!connected[j]) {
					continue;
				}
				if (usb_connectors[j] == usb_cables[cable].connectors[i]) {
					found = true;
				}
			}
			if (!found) {
				match = false;
			}
		}
		if (!match) {
			continue;
		}
		// the connector match
		uint8_t pair_defined, pair_undefined, pair_disconnected, pair_error;
		match = usb_cables_check_cable(&usb_cables[cable], &pair_defined, &pair_undefined, &pair_disconnected, &pair_error);
		if (match) {
			matches++;
			printf("- %s\n",  usb_cables[cable].name);
		}
	}
	printf("%u matching cable(s) found\n", matches++);

	usb_pins_float(); // put all pins back in safe floating state
}

/** set or show pin value
 *  @param[in] argument pin number and level
 */
static void command_pin(void* argument)
{
	char* pin_str = NULL; // to parse the pin number
	char* pin_level = NULL; // to parse the pin level
	const char* delimiter = " "; // words are separated by spaces
	uint8_t pin_nb = 0; // parsed pin number
	if (argument) { // pin number and level might have been provided
		pin_str = strtok((char*)argument, delimiter); // get pin number string
		if (pin_str) {
			pin_nb = strtoul(pin_str, NULL, 10); // parse pin number
			pin_level = strtok(NULL, delimiter); // get pin level
		}
	}

	// print header
	if (!pin_level) {
		printf("pin set and state (H: out high, L: out low, h in high, l in low, x in floating):\n");
	} else {
		printf("setting pin\n");
	}

	uint8_t pin_i = 0; // current pin
	for (uint8_t connector = 0; connector < LENGTH(usb_connectors); connector++) { // test every connector
		bool connector_print = (!pin_str || (pin_str && pin_nb >= pin_i && pin_nb < pin_i + usb_connectors[connector]->pins_nb)); // if a pin information will be printed for this connector
		if (connector_print) {
			printf("%s (%s):\n", usb_connectors[connector]->name, usb_connectors[connector]->host ? "host" : "device"); // print connector name
		}
		for (uint8_t pin = 0; pin < usb_connectors[connector]->pins_nb; pin++) { // test every pin
			uint32_t pin_port = usb_connectors[connector]->pins[pin].port; // GPIO port corresponding to USB pin
			uint16_t pin_pin = usb_connectors[connector]->pins[pin].pin; // GPIO pin corresponding to USB pin
			if (!pin_str || (!pin_level && pin_nb == pin_i)) { // show pin state
				printf("%03u %s: ", pin_i, usb_connectors[connector]->pins[pin].name); // print USB pin number
				uint8_t pin_pos = __builtin_ctz(pin_pin); // get the pin number (position of the 1 in the 16-bit)
				uint8_t offset = (pin_pos < 8) ? (pin_pos * 4) : ((pin_pos - 8) * 4); // get pin offset within port
				uint8_t mode = (((pin_pos < 8) ? GPIO_CRL(pin_port) : GPIO_CRH(pin_port)) >> (offset + 0)) & 0x3; // get mode from pin for port
				uint8_t conf = (((pin_pos < 8) ? GPIO_CRL(pin_port) : GPIO_CRH(pin_port)) >> (offset + 2)) & 0x3; // get configuration from pin for port
				// show set value
				if (0 == mode) { // pin configured as input
					if  (1 == conf) { // pin is in floating configuration
						putc('x');
					} else if (0 == (GPIO_ODR(pin_port) & pin_pin)) {
						putc('l');
					} else {
						putc('h');
					}
				} else { // pin configured as output
					if (0 == (GPIO_ODR(pin_port) & pin_pin)) {
						putc('L');
					} else {
						putc('H');
					}
				}
				// show actual value
				if (0 == mode) { // pin is configured as input
					bool high = (0 != gpio_get(pin_port, pin_pin)); // test if pin is high
					bool low = !high; // will be used to test if pin is low
					if  (1 == conf) { // pin is in floating configuration
						gpio_set_mode(pin_port, GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, pin_pin); // we will test if the input is floating by checking against a pull up and down
						gpio_set(pin_port, pin_pin); // pull up
						sleep_us(10); // wait for GPIO/line to settle
						high = (0 != gpio_get(pin_port, pin_pin)); // test if pin is high
						gpio_clear(pin_port, pin_pin); // pull down
						sleep_us(10); // wait for GPIO/line to settle
						low = (0 == gpio_get(pin_port, pin_pin)); // test if pin is low
						gpio_set_mode(pin_port, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, pin_pin); // put back to floating
					}
					// check and display result
					if (high && !low) { // pull down did not work
						putc('h'); // something is driving the pin high
					} else if (!high && low) { // pull up did not work
						putc('l'); // something is driving the pin low
					} else if (high && low) { // pull up and down worked
						putc('x'); // nothing is driving the pin
					} else { // pull up and down did not work
						putc('?'); // something is driving the pin randomly
					}
				} else { // pin is configured as output
					// only show the actual measured output, not the one set
					if (gpio_get(pin_port, pin_pin)) {
						putc('H'); // pin is high
					} else {
						putc('L'); // pin is low
					}
				}
				putc('\n');
			}
			if (pin_level && pin_nb == pin_i) { // set pin
				printf("%03u %s: %s", pin_i, usb_connectors[connector]->pins[pin].name, pin_level);
				switch (pin_level[0]) {
				case 'h':
					gpio_set(pin_port, pin_pin);
					gpio_set_mode(pin_port, GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, pin_pin);
					break;
				case 'H':
					gpio_set(pin_port, pin_pin);
					gpio_set_mode(pin_port, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, pin_pin);
					break;
				case 'l':
					gpio_clear(pin_port, pin_pin);
					gpio_set_mode(pin_port, GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, pin_pin);
					break;
				case 'L':
					gpio_clear(pin_port, pin_pin);
					gpio_set_mode(pin_port, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, pin_pin);
					break;
				case 'x':
				case 'X':
				default:
					gpio_set_mode(pin_port, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, pin_pin);
				}
				putc('\n');
			}
			pin_i++; // increase global pin number
		} // pin
		if (connector_print) {
			putc('\n'); // separate connectors for readability
		}
	} // connector
}

/** run self test to test board connection to connectors
 *  @param[in] argument no argument required
 */
static void command_test(void* argument)
{
	(void)argument; // we won't use the argument

	usb_pins_float(); // start with all pins in safe floating state
	printf("= test =\n");
	printf("run test to check board connections\n");
	printf("press any key to interrupt test\n\n");

	// ensure all pins are floating
	printf("remove all cables from connectors\n");
	bool float_errors = true; // to test if all pins are floating
	while (float_errors) {
		float_errors = false; // restart test
		for (uint8_t connector = 0; connector < LENGTH(usb_connectors); connector++) { // test every connector
			for (uint8_t pin = 0; pin < usb_connectors[connector]->pins_nb; pin++) { // test every pin
				uint32_t pin_port = usb_connectors[connector]->pins[pin].port; // GPIO port corresponding to USB pin
				uint16_t pin_pin = usb_connectors[connector]->pins[pin].pin; // GPIO pin corresponding to USB pin
				gpio_set_mode(pin_port, GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, pin_pin); // we will test if the input is floating by checking against a pull up and down
				gpio_set(pin_port, pin_pin); // pull up
				sleep_us(10); // wait for GPIO/line to settle
				bool high = (0 != gpio_get(pin_port, pin_pin)); // test if pin is high
				gpio_clear(pin_port, pin_pin); // pull down
				sleep_us(10); // wait for GPIO/line to settle
				bool low = (0 == gpio_get(pin_port, pin_pin)); // test if pin is low
				gpio_set_mode(pin_port, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, pin_pin); // put back to floating
				if (high && low) { // pull up and down worked
				} else { // pull up or down did not work
					printf("%s (%s) %s is not floating\n", usb_connectors[connector]->name, usb_connectors[connector]->host ? "host" : "device", usb_connectors[connector]->pins[pin].name); // print erroneous pin
					float_errors = true; // remember there is an error
				}
			} // pin
		} // connector
		if (float_errors) {
			if (user_input_available) { // user interruption
				goto end;
			}
			sleep_ms(500); // wait a bit before retesting
			if (user_input_available) { // user interruption
				goto end;
			}
		}
	} // float_errors
	printf("all pins are floating\n\n");

	// cables to test
	const struct usb_cable_t test_cables[] = {
		usb_cables[9], // A (host) - B 3.0 shielded cable
		usb_cables[14], // A (device) - B 3.0 shielded cable
		usb_cables[17], // A (host) - miniB 2.0 shielded cable
		usb_cables[25], // A (host) - microB 3.0 shielded cable
		usb_cables[31], // C (host) shunt
		usb_cables[32], // C (device) shunt
	};

	for (uint8_t cable = 0; cable < LENGTH(test_cables); cable++) {
		printf("connect %s cable to connectors:\n", test_cables[cable].name);
		for (uint8_t connector = 0; connector < test_cables[cable].connectors_nb; connector++) {
			printf("- %s (%s)\n", test_cables[cable].connectors[connector]->name, test_cables[cable].connectors[connector]->host ? "host" : "device");
		}
		bool cable_ok = false; // if the cable is connected
		while (!cable_ok) { // wait until all pin pairs of cable are connected
			uint8_t defined, undefined, disconnected, error; // pair counting variables
			cable_ok = usb_cables_check_cable(&test_cables[cable], &defined, &undefined, &disconnected, &error); // test cable
			if (!cable_ok && defined > 0) { // not all pairs are connected
				printf("connection issues: defined=%u/%u, undefined=%u, disconnected=%u, error=%u\n", defined, test_cables[cable].pin_pairs_nb, undefined, disconnected, error); // show issue summary
			}
			if (!cable_ok) {
				if (user_input_available) { // user interruption
					goto end;
				}
				sleep_ms(500); // wait a bit before retesting
				if (user_input_available) { // user interruption
					goto end;
				}
			}
		}
		printf("cable connections are OK\n\n");
	}

	printf("all connectors are OK, the board is fine\n");
end:
	usb_pins_float(); // put pins back to safe state
	if (user_input_available) {
		printf("test interrupted\n");
		while (user_input_available) { // test has been interrupted
			user_input_get(); // discard input
		}
	}
}


/** list of all supported commands */
static const struct menu_command_t menu_commands[] = {
	{
		.shortcut = 'h',
		.name = "help",
		.command_description = "display help",
		.argument = MENU_ARGUMENT_NONE,
		.argument_description = NULL,
		.command_handler = &command_help,
	},
	{
		.shortcut = 'V',
		.name = "version",
		.command_description = "show software and hardware version",
		.argument = MENU_ARGUMENT_NONE,
		.argument_description = NULL,
		.command_handler = &command_version,
	},
	{
		.shortcut = 'U',
		.name = "uptime",
		.command_description = "show uptime",
		.argument = MENU_ARGUMENT_NONE,
		.argument_description = NULL,
		.command_handler = &command_uptime,
	},
#if RTC_DATE_TIME
	{
		.shortcut = 'D',
		.name = "date",
		.command_description = "show/set date and time",
		.argument = MENU_ARGUMENT_STRING,
		.argument_description = "[YYYY-MM-DD HH:MM:SS]",
		.command_handler = &command_datetime,
	},
#endif
	{
		.shortcut = 'R',
		.name = "reset",
		.command_description = "reset board",
		.argument = MENU_ARGUMENT_NONE,
		.argument_description = NULL,
		.command_handler = &command_reset,
	},
	{
		.shortcut = 'B',
		.name = "bootloader",
		.command_description = "reboot into DFU bootloader",
		.argument = MENU_ARGUMENT_NONE,
		.argument_description = NULL,
		.command_handler = &command_bootloader,
	},
	{
		.shortcut = 'a',
		.name = "intra",
		.command_description = "test connector intra-connection",
		.argument = MENU_ARGUMENT_NONE,
		.argument_description = NULL,
		.command_handler = &command_intra,
	},
	{
		.shortcut = 'e',
		.name = "inter",
		.command_description = "test connector inter-connection",
		.argument = MENU_ARGUMENT_NONE,
		.argument_description = NULL,
		.command_handler = &command_inter,
	},
	{
		.shortcut = 'c',
		.name = "cables",
		.command_description = "test cables",
		.argument = MENU_ARGUMENT_NONE,
		.argument_description = NULL,
		.command_handler = &command_cables,
	},
	{
		.shortcut = 'f',
		.name = "find",
		.command_description = "find cable",
		.argument = MENU_ARGUMENT_NONE,
		.argument_description = NULL,
		.command_handler = &command_find,
	},
	{
		.shortcut = 'p',
		.name = "pin",
		.command_description = "set/show pin level",
		.argument = MENU_ARGUMENT_STRING,
		.argument_description = "[nb] [H/L/h/l/x]",
		.command_handler = &command_pin,
	},
	{
		.shortcut = 't',
		.name = "test",
		.command_description = "run board test",
		.argument = MENU_ARGUMENT_NONE,
		.argument_description = NULL,
		.command_handler = &command_test,
	},
};

static void command_help(void* argument)
{
	(void)argument; // we won't use the argument
	printf("available commands:\n");
	menu_print_commands(menu_commands, LENGTH(menu_commands)); // print global commands
}

static void command_version(void* argument)
{
	(void)argument; // we won't use the argument
	printf("firmware date: %04u-%02u-%02u\n", BUILD_YEAR, BUILD_MONTH, BUILD_DAY); // show firmware build date
	// get device identifier (DEV_ID)
	// 0x412: low-density, 16-32 kB flash
	// 0x410: medium-density, 64-128 kB flash
	// 0x414: high-density, 256-512 kB flash
	// 0x430: XL-density, 768-1024 kB flash
	// 0x418: connectivity
	puts("device family: ");
	switch (DBGMCU_IDCODE & DBGMCU_IDCODE_DEV_ID_MASK) {
		case 0: // this is a known issue document in STM32F10xxC/D/E Errata sheet, without workaround
			puts("unreadable\n");
			break;
		case 0x412:
			puts("low-density\n");
			break;
		case 0x410:
			puts("medium-density\n");
			break;
		case 0x414:
			puts("high-density\n");
			break;
		case 0x430:
			puts("XL-density\n");
			break;
		case 0x418:
			puts("connectivity\n");
			break;
		default:
			puts("unknown\n");
			break;
	}
	// show flash size
	puts("flash size: ");
	if (0xffff == DESIG_FLASH_SIZE) {
		puts("unknown (probably a defective micro-controller\n");
	} else {
		printf("%u KB\n", DESIG_FLASH_SIZE);
	}
	// display device identity
	printf("device id: %08x%08x%08x\n", DESIG_UNIQUE_ID0, DESIG_UNIQUE_ID1, DESIG_UNIQUE_ID2);
}

static void command_uptime(void* argument)
{
	(void)argument; // we won't use the argument
	uint32_t uptime = (rtc_get_counter_val() - time_start) / RTC_TICKS_SECOND; // get time from internal RTC
	printf("uptime: %u.%02u:%02u:%02u\n", uptime / (24 * 60 * 60), (uptime / (60 * 60)) % 24, (uptime / 60) % 60, uptime % 60);
}

#if RTC_DATE_TIME
static void command_datetime(void* argument)
{
	char* datetime = (char*)argument; // argument is optional date time
	if (NULL == argument) { // no date and time provided, just show the current day and time
		time_t time_rtc = rtc_get_counter_val() / RTC_TICKS_SECOND; // get time from internal RTC
		struct tm* time_tm = localtime(&time_rtc); // convert time
		printf("date: %d-%02d-%02d %02d:%02d:%02d\n", 1900 + time_tm->tm_year, time_tm->tm_mon, time_tm->tm_mday, time_tm->tm_hour, time_tm->tm_min, time_tm->tm_sec);
	} else { // date and time provided, set it
		const char* malformed = "date and time malformed, expecting YYYY-MM-DD HH:MM:SS\n";
		struct tm time_tm; // to store the parsed date time
		if (strlen(datetime) != (4 + 1 + 2 + 1 + 2) + 1 + (2 + 1 + 2 + 1 + 2)) { // verify date/time is long enough
			printf(malformed);
			return;
		}
		if (!(isdigit((int8_t)datetime[0]) && isdigit((int8_t)datetime[1]) && isdigit((int8_t)datetime[2]) && isdigit((int8_t)datetime[3]) && '-' == datetime[4] && isdigit((int8_t)datetime[5]) && isdigit((int8_t)datetime[6]) && '-' == datetime[7] && isdigit((int8_t)datetime[8]) && isdigit((int8_t)datetime[9]) && ' ' == datetime[10] && isdigit((int8_t)datetime[11]) && isdigit((int8_t)datetime[12]) && ':' == datetime[13] && isdigit((int8_t)datetime[14]) && isdigit((int8_t)datetime[15]) && ':' == datetime[16] && isdigit((int8_t)datetime[17]) && isdigit((int8_t)datetime[18]))) { // verify format (good enough to not fail parsing)
			printf(malformed);
			return;
		}
		time_tm.tm_year = strtol(&datetime[0], NULL, 10) - 1900; // parse year
		time_tm.tm_mon = strtol(&datetime[5], NULL, 10); // parse month
		time_tm.tm_mday = strtol(&datetime[8], NULL, 10); // parse day
		time_tm.tm_hour = strtol(&datetime[11], NULL, 10); // parse hour
		time_tm.tm_min = strtol(&datetime[14], NULL, 10); // parse minutes
		time_tm.tm_sec = strtol(&datetime[17], NULL, 10); // parse seconds
		time_t time_rtc = mktime(&time_tm); // get back seconds
		time_start = time_rtc * RTC_TICKS_SECOND + (rtc_get_counter_val() - time_start); // update uptime with current date
		rtc_set_counter_val(time_rtc * RTC_TICKS_SECOND); // save date/time to internal RTC
		printf("date and time saved: %d-%02d-%02d %02d:%02d:%02d\n", 1900 + time_tm.tm_year, time_tm.tm_mon, time_tm.tm_mday, time_tm.tm_hour, time_tm.tm_min, time_tm.tm_sec);
	}
}
#endif

static void command_reset(void* argument)
{
	(void)argument; // we won't use the argument
	scb_reset_system(); // reset device
	while (true); // wait for the reset to happen
}

static void command_bootloader(void* argument)
{
	(void)argument; // we won't use the argument
	// set DFU magic to specific RAM location
	__dfu_magic[0] = 'D';
	__dfu_magic[1] = 'F';
	__dfu_magic[2] = 'U';
	__dfu_magic[3] = '!';
	scb_reset_system(); // reset system (core and peripherals)
	while (true); // wait for the reset to happen
}

/** process user command
 *  @param[in] str user command string (\0 ended)
 */
static void process_command(char* str)
{
	// ensure actions are available
	if (NULL == menu_commands || 0 == LENGTH(menu_commands)) {
		return;
	}
	// don't handle empty lines
	if (!str || 0 == strlen(str)) {
		return;
	}
	bool command_handled = false;
	if (!command_handled) {
		command_handled = menu_handle_command(str, menu_commands, LENGTH(menu_commands)); // try if this is not a global command
	}
	if (!command_handled) {
		printf("command not recognized. enter help to list commands\n");
	}
}

/** program entry point
 *  this is the firmware function started by the micro-controller
 */
void main(void);
void main(void)
{
	rcc_clock_setup_in_hse_8mhz_out_72mhz(); // use 8 MHz high speed external clock to generate 72 MHz internal clock

#if DEBUG
	// enable functionalities for easier debug
	DBGMCU_CR |= DBGMCU_CR_IWDG_STOP; // stop independent watchdog counter when code is halted
	DBGMCU_CR |= DBGMCU_CR_WWDG_STOP; // stop window watchdog counter when code is halted
	DBGMCU_CR |= DBGMCU_CR_STANDBY; // allow debug also in standby mode (keep digital part and clock powered)
	DBGMCU_CR |= DBGMCU_CR_STOP; // allow debug also in stop mode (keep clock powered)
	DBGMCU_CR |= DBGMCU_CR_SLEEP; // allow debug also in sleep mode (keep clock powered)
#else
	// setup watchdog to reset in case we get stuck (i.e. when an error occurred)
	iwdg_set_period_ms(WATCHDOG_PERIOD); // set independent watchdog period
	iwdg_start(); // start independent watchdog
#endif

	board_setup(); // setup board
	usb_cdcacm_setup(); // setup USB CDC ACM (for printing)
	printf("\nwelcome to the CuVoodoo USB cable tester\n"); // print welcome message

#if DEBUG
	// show reset cause
	if (RCC_CSR & (RCC_CSR_LPWRRSTF | RCC_CSR_WWDGRSTF | RCC_CSR_IWDGRSTF | RCC_CSR_SFTRSTF | RCC_CSR_PORRSTF | RCC_CSR_PINRSTF)) {
		puts("reset cause(s):");
		if (RCC_CSR & RCC_CSR_LPWRRSTF) {
			puts(" low-power");
		}
		if (RCC_CSR & RCC_CSR_WWDGRSTF) {
			puts(" window-watchdog");
		}
		if (RCC_CSR & RCC_CSR_IWDGRSTF) {
			puts(" independent-watchdog");
		}
		if (RCC_CSR & RCC_CSR_SFTRSTF) {
			puts(" software");
		}
		if (RCC_CSR & RCC_CSR_PORRSTF) {
			puts(" POR/PDR");
		}
		if (RCC_CSR & RCC_CSR_PINRSTF) {
			puts(" pin");
		}
		putc('\n');
		RCC_CSR |= RCC_CSR_RMVF; // clear reset flags
	}
#endif
#if !(DEBUG)
	// show watchdog information
	printf("setup watchdog: %.2fs", WATCHDOG_PERIOD / 1000.0);
	if (FLASH_OBR & FLASH_OBR_OPTERR) {
		puts(" (option bytes not set in flash: software wachtdog used, not automatically started at reset)\n");
	} else if (FLASH_OBR & FLASH_OBR_WDG_SW) {
		puts(" (software watchdog used, not automatically started at reset)\n");
	} else {
		puts(" (hardware watchdog used, automatically started at reset)\n");
	}
#endif

	// setup RTC
	rtc_auto_awake(RCC_HSE, 8000000 / 128 / RTC_TICKS_SECOND - 1); // use High Speed External oscillator (8 MHz / 128) as RTC clock (VBAT can't be used to keep the RTC running)
	rtc_auto_awake(RCC_HSE, 8000000 / 128 - 1); // use High Speed External oscillator (8 MHz / 128) as RTC clock (VBAT can't be used to keep the RTC running)
	rtc_interrupt_enable(RTC_SEC); // enable RTC interrupt on "seconds"
	nvic_enable_irq(NVIC_RTC_IRQ); // allow the RTC to interrupt
	time_start = rtc_get_counter_val(); // get start time from internal RTC

	// setup USB connectors
	gpio_primary_remap(AFIO_MAPR_SWJ_CFG_JTAG_OFF_SW_ON, 0); // only use SWD and reuse JTAG pins
	rcc_periph_clock_enable(RCC_GPIOA); // enable clock to all GPIO port domains since we use them all
	rcc_periph_clock_enable(RCC_GPIOB); // enable clock to all GPIO port domains since we use them all
	rcc_periph_clock_enable(RCC_GPIOC); // enable clock to all GPIO port domains since we use them all
	rcc_periph_clock_enable(RCC_GPIOD); // enable clock to all GPIO port domains since we use them all
	rcc_periph_clock_enable(RCC_GPIOE); // enable clock to all GPIO port domains since we use them all
	rcc_periph_clock_enable(RCC_GPIOF); // enable clock to all GPIO port domains since we use them all
	rcc_periph_clock_enable(RCC_GPIOG); // enable clock to all GPIO port domains since we use them all
	usb_pins_float(); // pull all pins to floating

	// setup terminal
	terminal_prefix = ""; // set default prefix
	terminal_process = &process_command; // set central function to process commands
	terminal_setup(); // start terminal

	// start main loop
	bool action = false; // if an action has been performed don't go to sleep
	while (true) { // infinite loop
		iwdg_reset(); // kick the dog
		if (user_input_available) { // user input is available
			action = true; // action has been performed
			led_toggle(); // toggle LED
			char c = user_input_get(); // store receive character
			terminal_send(c); // send received character to terminal
		}
		if (rtc_internal_tick_flag) { // the internal RTC ticked
			rtc_internal_tick_flag = false; // reset flag
			action = true; // action has been performed
			if (0 == (rtc_get_counter_val() % RTC_TICKS_SECOND)) { // one seond has passed
				led_toggle(); // toggle LED (good to indicate if main function is stuck)
			}
		}
		if (action) { // go to sleep if nothing had to be done, else recheck for activity
			action = false;
		} else {
			__WFI(); // go to sleep
		}
	} // main loop
}

/** @brief interrupt service routine called when tick passed on RTC */
void rtc_isr(void)
{
	rtc_clear_flag(RTC_SEC); // clear flag
	rtc_internal_tick_flag = true; // notify to show new time
}