Programm loss

Hi all,

i am haveing strange Problems with the arduinoi Board. I am using the arduino as an interface to max msp, powered through the usb plug.

OH sorry not finished......

So again. I have wired a very simple circuit to the board. the components are 3 LEDs, and 3 Schurter Capacitive touchsensors. Verything seems to work fine, but after a few (i guess 20) restarts the Programm on the Atmega8 was lost! After reprogramming the arduino again, verything works out fine.

So how can i prevend the progroamm being erased?

any suggestions?

Is there a way to protect the Programm on the atmeag8 via fuse bits?




i figured out that the easiest way to achive this programmloss/startup problem is to attach a capacitor (i used a 4700 µF Elko) direkt to +5V and GND. Switch external power on and off a few times. Then the stratup/programmloss problems arise.

I have had various problems with the FTDI chip on other boards. Sometimes this chip behaves abnormal....perhabs erasing the application on the µC.

Any comments on that?

Thanks for help and comments.



do you need the 4700Uf capacitor? it will take several milliseconds, if not more, for the regulator to fill that cap... my guess is that the watchdog, or whatever is watching the voltage levels in the chip to say it's ok to start program execution, is saying the +5V voltage rise is too slow. Would 470Uf do it? 4700 is really huge! The Arudino regulator is a 78M05, rated for 500ma... how much current do the cpacitive sensors draw?


Hi Daniel,

i don't need the capacitor,- it was perhabs some kind of missleading- I just noticed by chance that the same problem i have with some kind of "normal circuit" every 20-50th powerup, happens every second or third powerup when attached the capacitor....... -it's hard to search for problems solution when you have to powerup the Board 50 times hoping to get the malfunction....-

I guess this shows that some "noise" on the +5V circuit can erase the application and/or confuse the bootloader/FTDI in such way that the application does not start..... repowerup the board does noz solve the problem.

Answeres toi the question: The capacitive sensors are Schurter ones with the ID 1243.5213.1.1, they draw normally 5mA (and switching current max 175mA regualted by the arduino Board).

My Ansatz: *separte the arduino circuit totally from all other electronic device (through optocouplres and another +5V circuit). *protect the application by some lockbit (any advice?) *try out some other BrownOut Options (any advice?) *try some other Bootloader. (any advice?)

Thanks for any comment and help


Hi Stephan,

can I ask, in the cases where you apply the power and the program does not start up properly, what happens if you leave the power applied and simply press the reset button? Does it start up normally?


Hallo Daniel,

in front of, thanks for your interest...

The power is applied through the 9V external Power ( the female header not the plug). An USB cable powers the FTDI chip for transferring data to max/msp/jitter. Pressing Reset doesent work in neither combination with powerup/down. This does not happen to one specific board, i have tried different.

Yesterday i've deleted the bootloader for the chip, now running the pure application with lockbits for memory/application protection enabled. haven't got hte chance to test it. may be after the weekend.