Add partially task 1

.gitignore

+**/bin

tasks/task1/Makefile

+# name of your application
+APPLICATION = blinky
+
+# If no BOARD is found in the environment, use this default:
+BOARD ?= nucleo-f401re
+
+# This has to be the absolute path to the RIOT base directory:
+RIOTBASE ?= $(CURDIR)/../../deps/RIOT
+
+# Comment this out to disable code in RIOT that does safety checking
+# which is not needed in a production environment but helps in the
+# development process:
+DEVELHELP ?= 1
+
+# Change this to 0 show compiler invocation lines by default:
+QUIET ?= 1
+
+# Use a peripheral timer for the delay, if available
+FEATURES_REQUIRED += periph_timer
+FEATURES_REQUIRED += periph_gpio_irq
+USEMODULE += ztimer
+USEMODULE += ztimer_usec
+USEMODULE += periph_gpio
+
+include $(RIOTBASE)/Makefile.include

tasks/task1/main.c

+#include <stdio.h>
+#include "board.h"
+#include "periph/gpio.h"
+#include "ztimer.h"
+
+void timer_cb (void *arg) {
+  (void)arg;
+  gpio_toggle(LED0_PIN);
+  gpio_irq_enable(BTN0_PIN);
+}
+
+void button_irq_handler(void *arg) {
+  (void)arg;
+  static ztimer_t timer_handler = {
+    .callback = timer_cb,
+    .arg = NULL
+  };
+  gpio_irq_disable(BTN0_PIN);
+  ztimer_set(ZTIMER_USEC, &timer_handler, 300 * US_PER_MS);
+}
+
+int main(void) {
+  gpio_init(LED0_PIN, GPIO_OUT);
+  gpio_init(BTN0_PIN, GPIO_IN_PU);
+  gpio_init_int(BTN0_PIN, GPIO_IN_PU, GPIO_BOTH, button_irq_handler, NULL);
+
+  for (;;) {
+    ztimer_sleep(ZTIMER_USEC, US_PER_SEC);
+  }
+}
+

tasks/task1/main.c.1

+#include <stdio.h>
+
+#include "board.h"
+#include "periph/gpio.h"
+#include "ztimer.h"
+
+int main(void) {
+  gpio_t led = LED0_PIN;// GPIO_PIN(0, 2);
+  gpio_init(led, GPIO_OUT);
+  while (1) {
+    gpio_toggle(led);
+    LED0_TOGGLE;
+    puts("Blink! (No LED present or configured...)");
+    ztimer_sleep(ZTIMER_USEC, 1 * US_PER_SEC);
+  }
+  return 0;
+}