diff --git a/src/main/common/string_light.c b/src/main/common/string_light.c
new file mode 100755
index 0000000000..1546f733c4
--- /dev/null
+++ b/src/main/common/string_light.c
@@ -0,0 +1,74 @@
+/*
+ * This file is part of Cleanflight.
+ *
+ * Cleanflight is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Cleanflight is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <limits.h>
+
+#include "string_light.h"
+#include "typeconversion.h"
+
+int sl_isalnum(int c)
+{
+    return sl_isdigit(c) || sl_isupper(c) || sl_islower(c);
+}
+
+int sl_isdigit(int c)
+{
+    return (c >= '0' && c <= '9');
+}
+
+int sl_isupper(int c)
+{
+    return (c >= 'A' && c <= 'Z');
+}
+
+int sl_islower(int c)
+{
+    return (c >= 'a' && c <= 'z');
+}
+
+int sl_tolower(int c)
+{
+    return sl_isupper(c) ? (c) - 'A' + 'a' : c;
+}
+
+int sl_toupper(int c)
+{
+    return sl_islower(c) ? (c) - 'a' + 'A' : c;
+}
+
+int sl_strcasecmp(const char * s1, const char * s2)
+{
+    return sl_strncasecmp(s1, s2, INT_MAX);
+}
+
+int sl_strncasecmp(const char * s1, const char * s2, int n)
+{
+    const unsigned char * ucs1 = (const unsigned char *) s1;
+    const unsigned char * ucs2 = (const unsigned char *) s2;
+
+    int d = 0;
+
+    for ( ; n != 0; n--) {
+        const int c1 = sl_tolower(*ucs1++);
+        const int c2 = sl_tolower(*ucs2++);
+        if (((d = c1 - c2) != 0) || (c2 == '\0')) {
+            break;
+        }
+    }
+
+    return d;
+}
diff --git a/src/main/common/string_light.h b/src/main/common/string_light.h
new file mode 100755
index 0000000000..005a6c6b12
--- /dev/null
+++ b/src/main/common/string_light.h
@@ -0,0 +1,28 @@
+/*
+ * This file is part of Cleanflight.
+ *
+ * Cleanflight is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Cleanflight is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+int sl_isalnum(int c);
+int sl_isdigit(int c);
+int sl_isupper(int c);
+int sl_islower(int c);
+int sl_tolower(int c);
+int sl_toupper(int c);
+
+int sl_strcasecmp(const char * s1, const char * s2);
+int sl_strncasecmp(const char * s1, const char * s2, int n);