Help with serial Arduino

Hi, I’ve recently built the serial Arduino single sided from scratch. I’ve loaded the bootloader without problems, the led blinks when reset button is pressed. The problem comes when I try to upload a program using the serial cable. I’m using pin 5 for ground and 2&3 for Tx and Rx. I’m using win xp and Arduino version 09. when I try to upload the following message appears:

Binary sketch size: 862 bytes (of a 7168 byte maximum)

avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

I tried everything, lower baudrate, changed the COM number, swapped Tx with Rx, pressing reset before/after upload and nothing works, I’ve no idea what to do next. Is there anything elese I should check? Please help.

Thanks in advance

I am new to Arduino and have been researching the issue with communications between a standard serial port and the Arduino. I assumed that I could connect pins 2 and 3 to the TX and RX pins on the Arduino and upload a sketch. Apparently this doesn’t work because the computer COM ports are RS232 and the ATMEL is a TTL serial chip. I didn’t know there were different protocols but Paul Badger over at gave me a little explanation about it. Anyway, he directed me to and the P4 which converts RS232 to TTL serial. I ordered a few kits. I am making an assumption that the TX and RX work the same way with Pauls BBB"Arduino" and the Diecimila RX/TX being that they have the same chip. I do not know why I have not read about this on this site. Of course the confirmation of this solution will occur after the receipt, assembly and test of the P4. I will test with both BBB and Arduino.
I am amazed that this is not something addressed outside the forums. I have seen a number of forum posts about this subject with little to no resolve.

I forgot to also include a link to a well explained description of the TTL to RS232:

Batou, do you have the NG or Diecimila bootloader?

David, thanks for the information. It’ll help me to better understand how the arduino works.

nkcelectronics: I don’t know what bootloader is in my arduino, I’m using an atmega8, the serial single sided version. I just uploaded the bootloader that came with the arduino 0009.
Luckily I solved the communication problem with the board. It seems that in my current computer, although I disable the antivirus and firewall there is still a hidden, invisible program preventing me to access the serial port. I created a new user, without deleting the old of course. This new user is “cleaner”: it doesn’t has all the programs and modifications my older user has. There, I only had to disable ZoneAlarm and my little Arduino finally worked