[SOLVED] Sketch-Upload via USB/ TTL-Adapter does'nt work ...

Hi Guys

I'm quite desperate. I tried (several times ...) to upload a sketch on my Arduino Pro Mini (3.3V) . The Board is connected via USB/ TTL-Adapter (PL2303-Chip). All i get is the well known message "avrdude: stk500_getsync(): not in sync: resp=0x00" and therefore a three times short blinking "TX"-LED on the Adapter-Board without any answer from the Arduino.

  • The chosen Board in Arduino IDE is correct ("Arduino Pro Mini (3.3V, 8MHz) ATMega 328")
  • The chosen COM-Port in Arduino IDE is correct
  • The USB/ TLL-Adapter are correctly recognized in Windows 7 Hardwaremanager (The same Adapter receive correctly signals from a GPS-Module!)
  • The same USB-Port/ IDE operate correctly with a 5 Volt Arduino Duemillenova (of course without the USB/ TTL-Adapter ...)
  • All Levels (TX, RX) are correct set to 3.3 Volts (tested with Oscilloscope)

The first Arduino-Board does'nt work from the beginning. A second Board take suprisingly a sketch (Blinking LED Example), but only one time and all i get is an very expensive blinking green LED :wink:

Any Help and Ideas appreciated!

How are you wired up? A standard PL2303 module will not have DTR broken out to act as a reset pin. Instead, they bring out the PL2303 chip's reset (input) pin which does not help.
Press reset on the promini when the IDE shows "Compiled xxx of 32xxx bytes".
If you select File:Preferences and turn on verbose outputs, can be easier to time the press correctly.

Some PL2303 modules have DTR broken out to a hole where you can add a pin or a wire so that you can connect it to GRN pin (green) and output a reset signal to the promini.

Are you relying on the IDE autoreset function or are you using a ‘well timed’ manual reset method? Many people trying to use those
PL2303 won’t work as the signal name reset on those modules are not the DTR or RTS signal needed to pulse the arduino module. You can hack the PL2303 sometimes depending on board layout of the module.

Sometimes things can be so easy. I tried the "well timed" manually reset while the IDE compile the sketch and now it works as expected at one go. Thanks a lot to you both!

CrossRoads:
[snip]
Press reset on the promini when the IDE shows "Compiled xxx of 32xxx bytes".
If you select File:Preferences and turn on verbose outputs, can be easier to time the press correctly.
[/snip]

oh man thank you! I have always had issues w/ certain sketches uploading and needing to well-time a reset, that will maake it so much easier.

OK, that's my final autoreset-solution: I solder a 100nF Cap on Pin 2 of the PL2303-Chip and connect it to a additional pin of the USB/TTL-Board. A fifth wire are connected to the RST-Pin of the Arduino Mini Pro. Works fine to me!