Second time loading sketch sync error

Development Tools IDE 1.x
1

I have scratch-built a duemilanove using an ATmega328P and an FTDI FT232RL. It uses a 16MHz resonator and gets power from the USB port. For the 328P to 232RL section, t's built per the reference schematic; double checked the layout and schematic. Running Arduino 1.0.1 on a Windows 7. Installed the standard bootloader using an UNO (SMD R2).

A sketch [in my case, Blink] will compile and upload only once after the bootloader has been installed. However, trying to upload any subsequent sketches yields the dreaded "avrdude: stk500_getsync(): not in sync: resp=0x00" error. This is very repeatable. I've re-loaded the bootloader 3 times. Each time the first upload works, but the second time produces the same error. The blink sketch still runs after power is cycled, so the original [first uploaded] program isn't being lost after power down or after the second uploading fails.

I also tried out optiboot. Optiboot loaded without problem, but the system choked and didn't upload any sketch; even selected the board type as both a Duemilanove and a UNO; neither worked.

Any suggestions on how to resolve this issue?

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(deleted)

3

They're set at:

atmega328.bootloader.unlock_bits=0x3F
atmega328.bootloader.lock_bits=0x0F

4

Try burning the bootloader again and before uploading Blink, change the delays to 100ms.

5

Did that to prove that the original sketch wasn't still loaded into memory. In fact, blink was modified to have different on/off times just to make sure.

I'm building up a second "bare minimum" board - just the FT232RL, 328P and associated circuitry. This should eliminate the possibility that downstream circuits are the root cause. More on that later...

6

Found the culprit, issue resolved!!! I had a 0.1uF cap from the /RESET line to ground. BTW, this is not the 0.1uF cap inline between the FT232RL (DTR#) and /RESET; that one is still there. Now I need to see the downstream effects on the peripheral circuit.

Thanks for everyone's help.

All the best,

Bob