added pin number commandline argument

diff --git a/pulser.c b/pulser.c
index 6362d67..3a0bdf1 100644 (file)
--- a/pulser.c
+++ b/pulser.c
@@ -59,6 +59,13 @@ int main(int argc, char **argv)
                                        }
                                        break;
 
+                               case 'p':
+                                       if(!argv[++i] || (pin = atoi(argv[i])) < 1 || pin >= 28) {
+                                               fprintf(stderr, "-p must be followed by a BCM pin number: 1-27\n");
+                                               return 1;
+                                       }
+                                       break;
+
                                case 'h':
                                        print_usage(argv[0]);
                                        return 0;
@@ -128,5 +135,6 @@ void print_usage(const char *argv0)
        printf(" -n: number of pulses to emit (default: 1)\n");
        printf(" -f: frequency of pulses in hz (default: 1)\n");
        printf(" -d: duty cycle [1, 255] (default: 128)\n");
+       printf(" -p: BCM pin number [1, 27] (default: 24)\n");
        printf(" -h: print usage and exit\n");
 }