Print an error on bad i2c request

Reference: https://github.com/MarlinFirmware/Marlin/pull/3713#issuecomment-218333678
9 years ago · a6d594665b
1 changed files with 5 additions and 1 deletions
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@ -5040,10 +5040,14 @@ inline void gcode_M121() { endstops.enable_globally(false); }
    uint8_t addr = code_seen('A') ? code_value_short() : 0;
    int bytes    = code_seen('B') ? code_value_short() : 0;

-    if (addr && bytes) {
+    if (addr && bytes > 0 && bytes <= 32) {
      i2c.address(addr);
      i2c.reqbytes(bytes);
    }
+    else {
+      SERIAL_ERROR_START;
+      SERIAL_ERRORLN("Bad i2c request");
+    }
  }

 #endif //EXPERIMENTAL_I2CBUS