Added usage and examples to readme

groundStation/README.md

@@ -23,3 +23,41 @@ If you wish to change the way the backend communicates to the quad and vice vers
 
 ## Modifying
 See MODIFYING for the software architecture/organization and how to add new functionality.
+
+## Using
+First, the backend daemon must be running. Run the backend with ./BackEnd. Note
+the environment variables in config.h, especially the backend socket path. The backend
+requires root for bluetooth, but can run as a normal user with TCP, as long as the
+socket path is writable by the user.
+
+Once the backend is running, various CLI tools can be used to view the state of the
+quad and send commands. Each of these tools is given as the first argument
+to the CLI program, for example, to monitor the quad, use `cli monitor`. Note that
+the backend socket environment variable must be set to the same value as it
+was for the backend. The CLI program also supports busybox-style symbolic links.
+For example, if there is a symlink named `monitor` that points to the `cli` binary,
+running the `monitor` program will effectively run `cli monitor`.
+
+The names of the binaries is subject to change.
+
+### Example
+In one terminal or screen, run the backend:
+
+`UCART_SOCKET=./ucart.socket ./BackEnd`
+
+This will activate the quad and the backend, and the backend will be available for
+connections from the frontend tools. One useful tool is the monitor. In another
+terminal window, run the monitor forever:
+
+`UCART_SOCKET=./ucart.socket ./cli monitor -f`
+
+This will begin a periodic monitoring that updates 10 times per second.
+
+Finally, in a third window, export the socket path:
+
+`export UCART_SOCKET=./ucart.socket`
+
+and then run any other tools to modify the quad, for example modifying PID constants:
+
+`./cli setpid --pitch -p 1.000`
+

groundStation/src/cli/cli_monitor.c

@@ -18,8 +18,10 @@ int cli_monitor(struct backend_conn * conn,	int argc, char **argv) {
 	static struct timespec elapsedTime;
 	static struct timespec lastChecked;
 	static int nsecs, rate = 10;
+	static int forever = 0;
 
- 	while ((c = getopt(argc, argv, "t:r:")) != -1) {
+
+ 	while ((c = getopt(argc, argv, "ft:r:")) != -1) {
 		switch(c) {
 			case 't' :
 				nsecs = atoi(optarg);
@@ -28,12 +30,19 @@ int cli_monitor(struct backend_conn * conn,	int argc, char **argv) {
 			case 'r' :
 				rate = atoi(optarg) + 1;
 				break;
+			case 'f' :
+				forever = 1;
+				break;
 			default :
 				break;
 		}
 	}
 
-	if(timeFlag) {
+	if (forever) {
+		for (;;) {
+			monitor(conn);
+		}
+	} else if (timeFlag) {
 		clock_gettime(CLOCK_REALTIME, &startTime);
 		clock_gettime(CLOCK_REALTIME, &lastChecked);
 		while((result = monitor(conn)) == 0) {
@@ -82,4 +91,4 @@ static void timespec_diff(struct timespec *start, struct timespec *result)
     }
 
     return;
-}
\ No newline at end of file
+}