Userland app for servomotor

examples/servo/Makefile

@@ -0,0 +1,11 @@
+# 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

@@ -0,0 +1,25 @@
+#include "../../libtock/interface/syscalls/servo_syscalls.h"
+#include <libtock-sync/services/alarm.h>
+#include <libtock/tock.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+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;
+  }
+
+  uint16_t angle;
+
+  // 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++) {
+    libtock_servo_angle(i);
+    libtocksync_alarm_delay_ms(100);
+    // Verifies if the function successfully returned the current angle.
+    if (libtock_current_servo_angle(&angle) == RETURNCODE_SUCCESS) {
+      printf("the current angle is: %d", angle);
+    }
+  }
+}

libtock/interface/syscalls/servo_syscalls.c

@@ -0,0 +1,21 @@
+#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);
+}
+
+returncode_t libtock_current_servo_angle(uint16_t* angle) {
+  uint32_t value     = 0;
+  syscall_return_t r = command(DRIVER_NUM_SERVO, 2, 0, 0);
+  // Converts the value returned by the servo, stored in `r`,
+  // and assigns it to `ret`.
+  returncode_t ret = tock_command_return_u32_to_returncode(r, &value);
+  *angle = (uint16_t)value;
+  return ret;
+}

libtock/interface/syscalls/servo_syscalls.h

@@ -0,0 +1,21 @@
+#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);
+// Requests the current angle from the servo.
+returncode_t libtock_current_servo_angle(uint16_t* angle);
+
+#ifdef __cplusplus
+}
+#endif