samples/button: button input example

An example of button driver.

Change-Id: I8af860058166d7ca5653f50ff585bc9784008f78
Origin: Original
Signed-off-by: Maciej Borzecki <maciek.borzecki@gmail.com>

samples/drivers/button/Makefile

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+MDEF_FILE = prj.mdef
+KERNEL_TYPE = micro
+BOARD ?= nucleo_f103rb
+CONF_FILE = prj.conf
+
+include ${ZEPHYR_BASE}/Makefile.inc

samples/drivers/button/README.txt

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+Title: Button demo
+
+Description:
+
+A simple button demo showcasing the use of GPIO input with interrupts.
+
+The demo assumes that a push button is connected to one of GPIO
+lines. The sample code is configured to work on Nucleo-64 F103RB
+board with button B1 providing the input.
+
+After startup, the program looks up a predefined GPIO device (GPIOC),
+and configures pin 13 in input mode, enabling interrupt generation on
+falling edge. During each iteration of the main loop, the state of
+GPIO line is monitored and printed to the serial console. When the
+input button gets pressed, the interrupt handler will print an
+information about this event along with its timestamp.
+
+--------------------------------------------------------------------------------
+
+Building and Running Project:
+
+It can be built for a nucleo_f103rb board as follows:
+
+    make
+
+The code may need adaption before running the code on another board.
+
+--------------------------------------------------------------------------------
+
+Troubleshooting:
+
+Problems caused by out-dated project information can be addressed by
+issuing one of the following commands then rebuilding the project:
+
+    make clean          # discard results of previous builds
+                        # but keep existing configuration info
+or
+    make pristine       # discard results of previous builds
+                        # and restore pre-defined configuration info
+
+--------------------------------------------------------------------------------

samples/drivers/button/prj.conf

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+CONFIG_STDOUT_CONSOLE=y

samples/drivers/button/prj.mdef

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+% Application       : Disco
+
+% TASK NAME  PRIO ENTRY STACK GROUPS
+% ==================================
+  TASK TASKA    7 main  2048 [EXE]

samples/drivers/button/src/Makefile

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+obj-y = main.o

samples/drivers/button/src/main.c

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+/*
+ * Copyright (c) 2016 Open-RnD Sp. z o.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <zephyr.h>
+#include <device.h>
+#include <gpio.h>
+
+#if defined(CONFIG_STDOUT_CONSOLE)
+#include <stdio.h>
+#define PRINT           printf
+#else
+#include <misc/printk.h>
+#define PRINT           printk
+#endif
+
+/* change this to use another GPIO port */
+#define PORT	"GPIOC"
+/* change this to use another GPIO pin */
+#define PIN	13
+/* change this to enable pull-up/pull-down */
+#define PULL_UP 0
+/* change this to use a different interrupt trigger */
+#define EDGE    (GPIO_INT_EDGE | GPIO_INT_ACTIVE_LOW)
+
+
+void button_pressed(struct device *gpiob, uint32_t pin)
+{
+	PRINT("Button pressed at %d\n", sys_tick_get_32());
+}
+
+void main(void)
+{
+	struct device *gpiob;
+
+	gpiob = device_get_binding(PORT);
+
+	gpio_pin_configure(gpiob, PIN,
+			GPIO_DIR_IN | GPIO_INT
+			| EDGE
+			| PULL_UP);
+	gpio_set_callback(gpiob, button_pressed);
+	gpio_pin_enable_callback(gpiob, PIN);
+
+	while (1) {
+		int val = 0;
+
+		gpio_pin_read(gpiob, PIN, &val);
+		PRINT("GPIO val: %d\n", val);
+		task_sleep(MSEC(500));
+	}
+}