Merge pull request #479 from tyler-potyondy/ewsn-tutorial

Thread Tutorial Updates

Author: ppannuto

examples/tutorials/thread_network/01_sensor_ipc/main.c

@@ -0,0 +1,21 @@
+#include <stdio.h>
+
+#include <libtock-sync/sensors/temperature.h>
+#include <libtock-sync/services/alarm.h>
+#include <libtock/kernel/ipc.h>
+#include <libtock/tock.h>
+
+static int current_temperature = 0;
+
+int main(void) {
+  // Measure temperature -- returned in the form 2200 => 22C
+  libtocksync_temperature_read(&current_temperature);
+
+  // Convert temperature
+  int whole_degree   = current_temperature / 100;
+  int decimal_degree = current_temperature % 100;
+
+  printf("Hello World, the temperature is: %i.%i\r\n", whole_degree, decimal_degree);
+
+  return 0;
+}

examples/tutorials/thread_network/01_sensor_ipc/Makefile renamed to examples/tutorials/thread_network/01_sensor_temperature/Makefile

@@ -5,47 +5,23 @@
 #include <libtock/kernel/ipc.h>
 #include <libtock/tock.h>
 
-// Global variable storing the current temperature. This is written to in the
-// main loop, and read from in the IPC handler. Because the app is single
-// threaded and has no yield point when writing the value, we do not need to
-// worry about synchronization -- reads never happen during a write.
 static int current_temperature = 0;
 
-static void sensor_ipc_callback(int pid, int len, int buf,
-                                __attribute__((unused)) void* ud) {
-  // A client has requested us to provide them the current temperature value.
-  // We must make sure that it provides us with a buffer sufficiently large to
-  // store a single integer:
-  if (len < ((int) sizeof(current_temperature))) {
-    // We do not inform the caller and simply return. We do print a log message:
-    puts("[thread-sensor] ERROR: sensor IPC invoked with too small buffer.\r\n");
-    return;
-  }
-
-  // The buffer is large enough, copy the current temperature into it:
-  memcpy((void*) buf, &current_temperature, sizeof(current_temperature));
-
-  // Let the client know:
-  ipc_notify_client(pid);
-}
-
 int main(void) {
-  // Measure the temperature once before registering ourselves as an IPC
-  // service. This ensures that we always return a correct (but potentially
-  // stale) temperature value.
-  libtocksync_temperature_read(&current_temperature);
 
-  // Register this application as an IPC service under its name:
-  ipc_register_service_callback("org.tockos.thread-tutorial.sensor",
-                                sensor_ipc_callback,
-                                NULL);
-
-  // We measure the temperature in the main loop and simply provide the latest
-  // reading in an IPC. This means that the control app does not have to wait
-  // for the temperature read system call to complete.
+  // We measure the temperature in the main loop and
+  // print this value to the console.
   while (1) {
+    // Measure temperature -- returned in the form 2200 => 22C
     libtocksync_temperature_read(&current_temperature);
-    // printf("Current temperature: %d\r\n", current_temperature);
+
+    // Convert temperature
+    int whole_degree   = current_temperature / 100;
+    int decimal_degree = current_temperature % 100;
+
+    printf("Current temperature: %i.%i\r\n", whole_degree, decimal_degree);
+
+    // Delay 1000 ms (1 second).
     libtocksync_alarm_delay_ms(1000);
   }
 }