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[on:]

Hi,
  Im trying to use the rx and tx pin to simulate and replace the USB port on my arduino UNO.. I am using the rx and tx pin of the arduino with a max232 IC.. Everything seems to work fine as i am able to get serial output from the arduino and even give serial input to the arduino. BUt when i try to upload code to the arduino using the same rx and tx pin , i get the not in sync error and the protocol error from the arduino IDE.
  I am powering the arduino from a 12v adapter and it works fine..The USB port is not used ( there is some problem with it ) . Any way on how to upload code to the arduino via the RX and TX pin?
Thanks..

[Reply #1 on:]

You need to Bypass the Firmware Loaded on the UNO's 8u2 Chip as the Loading into the ATmega happen's through it.

[Reply #2 on:]

Hi,
 thanks for your reply.. Could you please guide me as to how i should go about doing this?

[Reply #3 on:]

You are fighting an electrical conflict when trying to upload new sketches using the USB 8u2 on board serial converter chip and still being wired to your rs-232 convert chip. They are both wired to pins 0 & 1, thus the electrical conflict. Just disconnet the pins 0 and 1 wiring to your rs-232 chip and you will be able to upload from the PC, then reconnect the pins 0 and 1 wiring when done with the upload.

Lefty

[Reply #4 on:]

Well , its been over a month since my arduino stopped responding over USB for some reason.. I am able to send input to the arduino via USB ( serial connection) but not get output from the arduino. I was also not able to upload code to the arduino.. Im not sure why.. it randomly stopped working.. i guess that part is screwed up.. Which is why i thought i'd try using rx and tx pin to upload..
Thanks..

[Reply #5 on:]

RetroLefty says right prashanth , it's a situation of DEAD-LOCK as it happen's in Software development when same resource is to be used by two elements at the same time.

Do you have a Serial Port on your System?
make a Stand-Alone Atmega circuit ,just get it out of the Arduino board and use the PONY-PROG and you are on, it's definitely going to work, but make a Serial programmer for AVR's first.

[Reply #6 on:]

hey..thats something similar to what im trying to do here http://arduino.cc/forum/index.php/topic,54190.0.html .. tried burning the atmega8 hex files on a seperate atmega8.. but i think i screwed up in the lock bits part.. and im not sure if i can burn a atmega168 hex file to an atmega8.im looking for a good tutorial to guide me to burn the RIGHT arduino boot hex file to an atmega8.. with the right lock and fuse bits using avr studio..
Thanks..

[Reply #7 on:]

If you are trying to load your Sketch/Software on to the ATmega8 then you can compile the Sketch using the different board setting that uses the ATmega8 Controller and burn it using the Following Fuse Bit's.
 ATmega8: Use these fuse-bits and lock-bit.
hfuse = CA
lfuse = DF
unlock = 3F
lock = 0F

and you cannot burn bootloader's swapping them for other chips because the Siganture is Different and i'm not sure that will be accepted by the avr-gcc compiler.

Regards,
Nishant Sood

[Reply #8 on:]

thanks for your reply..so the fuse and lock bit settings are the same even if im burning a sketch's hex file or the bootloader's hex file?..the fuse and lock bit settings on this page for the atmega8 seem to be a little different http://www.arduino.cc/playground/Learning/Burn168 ..