add mising b2s function

main.c

@@ -129,6 +129,28 @@ int _write(int file, char *ptr, int len)
 	return -1;
 }
 
+char* b2s(uint32_t binary, uint8_t rjust)
+{
+	static char string[32+1] = {0}; // the string representation to return
+	int16_t bit = LENGTH(string)-1; // the index of the bit to print
+	string[bit--] = 0; // terminate string
+
+	while (binary) {
+		if (binary & 1) {
+			string[bit--] = '1';
+		} else {
+			string[bit--] = '0';
+		}
+		binary >>= 1;
+	}
+
+	while (32-bit-1<rjust && bit>=0) {
+		string[bit--] = '0';
+	}
+
+	return &string[bit+1];
+}
+
 /** @brief switch off all clock LEDs
  *  @note LEDs need to be set separately
  */