After reading another post CH340 Nano avrdude: stk500_getsync() not in sync resp=0xa4 I have discovered that the bootloader on current Nano v3.0 has been upgraded. However, the advice given to overcome this problem is based around a more modern version of the Arduino IDE communicating with an old bootloader. I have the reverse problem. I damaged my Arduino Nano that was working with a laptop running Windows XP and bought a replacement. It obviously has the latest bootloader installed so my version of the Arduino IDE v0021 (recommended to run on Windows XP) can no longer upload sketches to the board.
I have uploaded GRBL v1.1h to the Nano board from an Arduino IDE v1.8.19 installation on a Windows 7 computer but the older version of GRBL Control v0.8.1 running on Windows XP has compatibility issues with GRBL 1.1h. I need to upload an earlier version of GRBL that is compatible with GRBL Control v0.8.1 but the bootloader on the new Arduino Nano v3.0 runs at 115200 and the Arduino IDE v0021 expects a baud rate of 57600 so I get these errors
stk500_getsync():not in sync: resp=0x09
stk500_disable(): protocol error, expect=0x14, resp=0x51
Can I upload an older bootloader to a newer Arduino Nano so I can then flash an older version of GRBL that is compatible with GRBL Control v0.8.1 to run on Windows XP?