Add deactivated PT1000 measurement as error flag, startcode for calibration routine

stm-firmware/syscalls.c

@@ -1,4 +1,8 @@
 #include <stm-periph/uart.h>
+#include <sys/types.h>
+#include <errno.h>
+#include <stddef.h>
+
 
 char* _sbrk(int incr)
 {
@@ -12,12 +16,16 @@ char* _sbrk(int incr)
 	}
 
 	prev_heap_end = heap_end;
+
+
 	if (heap_end + incr > &heap_top) {
-		return 0;
+		errno = ENOMEM;
+		return (char *)-1;
 	}
 
 	heap_end += incr;
-	return (char*) prev_heap_end;
+
+	return (char *) prev_heap_end;
 }
 
 int _isatty(int fd)