Userland app for servomotor

examples/servo/Makefile

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+# Makefile for user application
+
+# Specify this directory relative to the current application.
+TOCK_USERLAND_BASE_DIR = ../..
+
+# Which files to compile.
+C_SRCS := $(wildcard *.c)
+
+# Include userland master makefile. Contains rules and flags for actually
+# building the application.
+include $(TOCK_USERLAND_BASE_DIR)/AppMakefile.mk

examples/servo/main.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+#include <libtock-sync/services/alarm.h>
+#include <libtock-sync/interface/servo.c>
+
+int main(void) {
+  // Checks if the driver exists and, if not, returns -1.
+	if (!libtock_servo_exists()) {
+    printf("There is no available servo\n");
+    return -1;
+  }
+  // Changes the angle of the servomotor from 0 to 180 degrees (waiting 0.1 ms between every change).
+  for (int i = 0; i<=180; i++) {
+    libtocksync_servo_angle(i);
+    libtocksync_alarm_delay_ms(100);
+  }
+}

libtock-sync/interface/servo.c

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+#include "servo.h"
+#include "../../libtock/interface/syscalls/servo_syscalls.h"
+
+returncode_t libtocksync_servo_angle(uint32_t angle) {
+  int err;
+  err = libtock_servo_angle(angle);
+  if (err != RETURNCODE_SUCCESS) return err;
+
+  return RETURNCODE_SUCCESS;
+}

libtock-sync/interface/servo.h

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+#pragma once
+#include <libtock/tock.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// ## Arguments
+//
+// - `angle`: The angle you want the servo to move.
+//
+// ## Return Value
+//
+// A returncode indicating whether the angle was changed successfully.
+returncode_t libtocksync_servo_angle(uint32_t angle);
+
+#ifdef __cplusplus
+}
+#endif

libtock/interface/syscalls/servo_syscalls.c

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+#include "servo_syscalls.h"
+#include <stdio.h>
+
+bool libtock_servo_exists(void) {
+  return driver_exists(DRIVER_NUM_SERVO);
+}
+
+returncode_t libtock_servo_angle(uint32_t angle) {
+  syscall_return_t cval = command(DRIVER_NUM_SERVO, 1, angle, 0);
+  return tock_command_return_novalue_to_returncode(cval);
+}

libtock/interface/syscalls/servo_syscalls.h

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+#pragma once
+
+#include "../../tock.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define DRIVER_NUM_SERVO 0x90009
+
+// Check if the servo system call driver is available on this board.
+bool libtock_servo_exists(void);
+
+// Change the angle.
+returncode_t libtock_servo_angle(uint32_t angle);
+
+#ifdef __cplusplus
+}
+#endif