I need to change a sketch remotely via an external device (not a PC) that has an RS232 with a TTL converter.
My issue is that I am getting no response on the serial port after the reboot. I can see the reboot happen on the led's and I am both manually and over the DTR pulling the reset pin low. So I am sure I am rebooting the MCU, but I am not getting anything that looks even close to the STK500 response. any ideas.
I have tried to send 0x50 0x20 (the enter programming command) but still nothing. the bootloader times out and starts the existing sketch, but I am not getting anything out of the serial.
I have confirmed that the serial works both on my device as on the Arduino, they can talk to each other over serial on a standard sketch. I have confirmed that serials are in identical configurations (I have gone through them all). I am using TX1 and RX1 not the USB cable.
What am I missing ???