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I have designed a board based on an ATmega2560 chip and I burned the bootloader by following this tutorial.

Now I am able to load Blinky and other programs using an FTDI cable. But the issue I am facing right now is the controller runs Blinky fine if I leave the FTDI connected there. If I disconnect the FTDI cable and power-cycle the board it is not running Blinky. If I connect the FTDI, right away it starts blinking.

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It looks like something is wrong with my RESET pin connection? Here is what my RESET circuitry looks like:

  • I also have tried by removing D1 diode but no luck !
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  • Looks like something wrong with my RESET pin connection ... how do you know. please post your schematic – jsotola Jan 13 '18 at 5:35
  • I am not having schematic but I have followed the circuit given above and in additional I put 0.1uf to connect RESET pin with FTDI. – HallMark Jan 13 '18 at 6:17
  • What happens if you momentarily short the reset line to ground and then release it? Also, what is your power source? Did you have the 5v line from the FTDI connected when it was working? Try to figure out which connections to the FTDI correlate with it starting to work. – Chris Stratton Jan 15 '18 at 5:49
  • Chris, I have 12v supply which is then stepped down to 5v. No I am not using power from FTDI connection. It starts running when I connect my board Ground with FTDI Ground Pin and FTDI plugged into my PC. I checked I have ground line common. – HallMark Jan 17 '18 at 15:01
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The issue was there was some noise on RX Pin of the chip and because of that when it is powered on in bootloader it was stuck at that place. And it was working good with FTDI because RX gets proper connection with my FTDI.

Solution:- Connect 10K pull-down on RX pin resolved this problem.

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Or get rid of C6, I have never used that in a design.

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    C6 was not a problem. I have posted the exact solution I found in this case. – HallMark Feb 9 '18 at 4:02

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