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1  Using Arduino / Installation & Troubleshooting / Re: Is my Atmega8u2 on Mega2560 board bricked? on: July 15, 2013, 08:19:35 pm
Thanks.  Now I will thoroughly check all the power buses on the shield and get a new Mega2560 board. If that works well I'd forget about this board.
2  Using Arduino / Installation & Troubleshooting / Re: Is my Atmega8u2 on Mega2560 board bricked? on: July 15, 2013, 07:18:48 pm
Now I've tried loopback by shorting the 8u2 end of the resistor network, putting the rx resistor out of question, still failed.

Also, there are some more erratic behaviours. The sketches upload fine with the tx resistor shorted when the board is powered from usb. But with external power they fail like before. I'm using the analoginoutserial example sketch to test the serial communication. It works fine when the tx resistor is shorted with both usb and external power.

Also with the analoginoutserial example, when I open the serial monitor, there is no data from the board, and the pin13 led lights up and stays lit. When I reset the board the serial communication begins, the tx led lights and the pin13 doesn't light up. But when uploading sketches, there's no need to manually reset.

Also, the if I run the example for 2-3 minutes with usb power,  the 8u2 gets warm.  Not hot,  but warmer than the 2560.  And with external power it gets even warmer.

I guess I'd need to replace the board totally. But still it's necessary to learn what actually happened so that it doesn't repeat with the new board. As it was supposed to be my first project that would be practically used in field.
3  Using Arduino / Installation & Troubleshooting / Re: Is my Atmega8u2 on Mega2560 board bricked? on: July 15, 2013, 04:22:41 pm
Did you bypass both Tx and Rx paths on the 1k resistor network?

No, only the TX path. Meaning, the TX of the Atmega2560 to RX (sorry for my mistake on previous post) of the Atmega 8u2.
4  Using Arduino / Installation & Troubleshooting / Re: Is my Atmega8u2 on Mega2560 board bricked? on: July 15, 2013, 12:54:33 pm
Follow up: the update process through FTDI USB to serial works flawlessly. Uploaded sketches runs flawlessly. Only, no communication through the atmega8u2 usb seral bridge.

Now I've noticed something. If I short/bypass the 1k resistor on only the mega2560 rx to 8u2 tx path, the problems are gone and the sketches upload fine. All serial communication through the built in usb serial bridge works fine too.

But even with the resistor bypassed the loopback test fails. Any idea on what might be happening?
5  Using Arduino / Installation & Troubleshooting / Is my Atmega8u2 on Mega2560 board bricked? on: July 15, 2013, 06:13:58 am
I have a Mega2560 Rev2 board which haven't been used for quite a while. Today I tried to use it with a shield for a project and couldn't upload any sketch to it. So I detached everything from the board, plugged the USB and tried to upload the blink example to test. The upload gets stuck for a long time and doesn't respond until I get frustrated (i've tried 5 minutes). And on the board, when the upload starts the RX LED flashes once for a brief moment, the TX doesn't flash at all and the L13 LED turns on and stays on. It stays on even if I close the IDE and until I disconnect the USB.

Note, the board is recognized properly on the windows device manager as Arduino Mega2560.

I tried the serial loopback test. It doesn't echo anything. Every time I send something on the serial monitor, the RX LED flashes, but the TX doesn't.

I also checked that the version of the 8u2 firmware was 00000. I uploaded it to 00001 with DFU mode with Atmel FLIP programmer and it uploaded well. During the firmware upload, the RX and TX both LEDs were lit, so the TX LED is not dead.

When I connected it with the shield today, I was powering the board with 12v from my computers ATX power supply through the DC barrel jack. The shield was separately powered from the 12v and didn't take power from Arduino. Also, I might have shorted the Arduino 5v and 3.3v output pin for a brief moment. Could this possibly killed the board?

I'm in the process of obtaining a separate FTDI USB to Serial adapter to check if I can upload through pin 0 and 1. Will post the results later.
6  Using Arduino / Microcontrollers / Re: Atmega328-PU non-optiboot bootloader not working on: October 13, 2012, 03:05:20 pm
Sorry for late reply. I tried with both SLOW_SCK on and off. But the Duemilanove bootloader never worked. I even tried the chip by putting it on a firend's Arduino NG board instead of bredboard. But it doesn't matter now, I am using the chips fine with optiboot recompiled with baudrate set to 57600bps. I'll be getting some better crystals next week, hope that will solve everything.

I would've posted a picture of the setup, but believe me or not, I don't even have a working camera for that. smiley-confuse
7  Using Arduino / Microcontrollers / Re: Atmega328-PU non-optiboot bootloader not working on: October 12, 2012, 05:49:30 am
Thanks for the reply.

I'm using 16 MHz Crystals, but they are cheap, and has low tolerance levels (for example, one of them can do baudrate up to 57600 but the same model another gives garbage at anything higher than 28800). And I have experience with other blink sketches but this is nothing like them. This blinks start as soon as I apply power, they are short blinks (.5s) with long gaps (1.5s) like it is trying to give the initial blinks of the bootloader but resets in the middle of the process.

Also, I'm using lfuse=0xFF, hfuse=0xDA and efuse=0x05 for Non-Optiboot, and lfuse=0xFF, hfuse=0xDE, efuse=0x05 for Optiboot.
8  Using Arduino / Microcontrollers / Atmega328-PU non-optiboot bootloader not working on: October 11, 2012, 07:57:03 pm
Hi, I tried to upgrade my breadboard arduino, and ended up ordering some Atmega328-PU instead of Atmega328P-PU chips. I could burn the bootloader to them by modifying the avrdude.conf file with no problem, but the problem I'm facing is, the chips aren't working with any bootloader other than the Uno optiboot.

I've tried the bootloaders for Atmega328 versions of Duemilanove, Nano and Pro and with each of them, the Pin 13 LED just keep giving short blinks every 1.5 seconds and nothing else happens. I've read somewhere in this forum that this happened to someone who apparently overflown the memory with a sketch which changed the watchdog timer settings. He solved it by re-flashing the bootloader, but in my case, the bootloader is causing the problem.

I've tried the Uno bootloader and it works fine, or at least the Pin 13 LED doesn't blink continuously. With optiboot, it blinks fast 3 times and then stops. But still, I can't use the optiboot because my 16MHz crystals are very cheap and cannot provide the accuracy required to support UART at baudrate 115200. I've once tried by recompiling optiboot with baudrate 57600 and it worked very well.

I'm using USBasp to burn the bootloader and a USB-Serial TTL converter based on the VUSB protocol.

Thanks for any Reply.
9  Development / Other Hardware Development / Re: 16.0083 MHz crystal with Atmega8 on: August 27, 2012, 10:48:03 am
Thanks. Going back to the breadboard now. smiley
10  Development / Other Hardware Development / Re: 16.0083 MHz crystal with Atmega8 on: August 27, 2012, 09:57:46 am
Thanks for the reply. So, would I need to recompile the bootloader with new F_CPU or just use the original one?

Also, I cannot order online as I live in a country where most shipping services either never reach or take ridiculously long time. I got all the caps and resistors already, only the crystal got me. But if I wait a I might be able to get correct crystals when the local stores replenish their stocks. But I don't know how long that will take.
11  Development / Other Hardware Development / 16.0083 MHz crystal with Atmega8 on: August 27, 2012, 09:41:49 am
Hi, I am a newbie to arduino and to the microcontrollers too. I am trying to build a cheap Arduino NG clone on a breadboard with atmega8, purely for educational/learning purposes. I seem to get everything right up to this point, using another Atmega8 with V-USB (http://www.obdev.at/products/vusb/index.html) for USB UART bridge, and everything else. The problem I have now is that surprisingly I can't find any 16MHz crystals on any local store.. I have 4MHz, 8MHz, 12MHz and the closest I got is marked 16.0083 MHz. So, can I somehow use the 16.0083 MHz crystal  and live with that? Can I do this with default bootloader for NG or would I have to compile one with different F_CPU value? And if I do that, would I be able to upload sketches with the UART bridge or use the UART for communicating with any PC while running the sketch?

Any help will be appreciated.
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