AVR-MT-128 Fuses messed up - Help Olimex!

Development Boards MicroMod
1

I accidentally set the fuses incorrectly on my AVR-MT-128. Now I cannot do anything with this board. I cannot reset the fuses or set them to new values and I can’t erase or program the chip.

I am using an AVRISP in AVRStudio and no matter what I do, it tells me “Entering programming mode… FAILED!”.

I have seen some discussion in other forums about fixing this for a atmega128, but I would like to see some instructions from Olimex for the AVR-MT-128.

Thanks in advance

2

Can someone from Olimex suggest a fix for my problem? Or is there another method of getting support from them other than this forum?

3

AVRs are ubiquous that you can shot your leg if you set the wrong fuse and end up with dead chip :slight_smile:

probably you enabled the external oscillator and now your device waits for external clock to move on - apply freqency to Xin pin of the crystal and you will bring your AVR to life

if you want to receive prompt reply send e-mail to support at olimex dot com.

Tsvetan

4

If I set the fuse to external crystal oscillator why does it need a square wave on the Xin pin? Why doesn’t the crystal oscillator just ‘work’?

5

this question should be addressed to Atmel who decided to design the AVRs this way, not to us :slight_smile:

Tsvetan

6

…

probably you enabled the external oscillator and now your device waits for external clock to move on - apply freqency to Xin pin of the crystal and you will bring your AVR to life

Who so? The MT128 board has an external crystal. I configured my MT128 with Fuse settings: CKSEL=1111, SUT=11, which implies a high frequency external oscillator. And this works fine with the 16MHz oscillator onboard the MT128.

Also, it is not possible to mess up any fuse via a ICSP programmer. The fuse that can block further ICSP is called SPIEN, and that can not be messed by a serial programmer. However, the LockBits can be messed up with ICSP. If you messed up one of those you will need to get a JTAG programmer to reset them I think.

Things to note about the MT128 board, which Olimex does not mention in their documentation:

  • The board ships with CKSEL=0001, SUT=01, which is default from Atmel. So the mega128 is running on an internal 1MHz oscillator. I only realized this after trying to get the %&#" USAR to send some simple chars to my PC. With the 16MHz crystal on the MT128 it is not unreasonable that new users assume that the chip is clocked with that.

  • JTAG support is disabled. So if you want to use a JTAG programmer you must first change the jtag fuse with another serial programmer.

erik

7

baluba:
Things to note about the MT128 board, which Olimex does not mention in their documentation:

  • The board ships with CKSEL=0001, SUT=01, which is default from Atmel. So the mega128 is running on an internal 1MHz oscillator. I only realized this after trying to get the %&#" USAR to send some simple chars to my PC. With the 16MHz crystal on the MT128 it is not unreasonable that new users assume that the chip is clocked with that.

  • JTAG support is disabled. So if you want to use a JTAG programmer you must first change the jtag fuse with another serial programmer.

I just pulled my mt128 out of the box, it's been sitting here for a few months, never been used. It was configured for external oscillator with JTAG enabled by default:

Fuse Low Byte = 0xef (1110 1111)
Fuse High Byte = 0x09 (0000 1001)
Fuse Extended Byte = 0xff (1111 1111)