HI All, I have a Sanguinololu that uses the Atmega1284p, and am having some trouble with. The endstops will not register and the motors will only spin in one direction no matter what settings are changed in firmware(I'm using Marlin, btw). After some searching I believe the problem is that the JTAG fuse settings for the chip are wrong, and that it must be disabled. I never uploaded the bootloader myself, and bought it with it already installed, so I'm not *exactly* sure how to fix it. I don't want to buy an ISP programmer at all, and I know I could buy a new chip from a different seller that has been tested, but if can fix it for free while learning something new, I'm willing to try. Worse case scenario I brick the chip, and have to buy a new one anyway. Can I use the Arduino Uno as an ISP programmer? I've seen various post that say you can and cannot. It's usually said that it has to be a pre- Arduino Uno, one that uses an FTDI chip. Also I believe there are memory limits that restrict what type of programmer can be used. If the UNO can be used as an ISP, can it handle the memory size of the 1284p? I'm also under the impression that you can change the Fuse settings without burning an whole new bootloader? Is that true? Thanks in advance. https://reprap.org/forum/read.php?13,311417,311417#msg-311417 Thu, 05 Mar 2026 12:14:10 -0500 Phorum 5.2.23 https://reprap.org/forum/read.php?13,311417,311859#msg-311859 https://reprap.org/forum/read.php?13,311417,311859#msg-311859 theruss007 Controllers Sun, 16 Feb 2014 21:49:57 -0500 https://reprap.org/forum/read.php?13,311417,311856#msg-311856 https://reprap.org/forum/read.php?13,311417,311856#msg-311856 theruss007 Controllers Sun, 16 Feb 2014 21:18:40 -0500 https://reprap.org/forum/read.php?13,311417,311644#msg-311644 https://reprap.org/forum/read.php?13,311417,311644#msg-311644 theruss007 Controllers Sun, 16 Feb 2014 11:42:24 -0500 https://reprap.org/forum/read.php?13,311417,311611#msg-311611 https://reprap.org/forum/read.php?13,311417,311611#msg-311611
But reading though the issues, wow, another C syntax trap! I thought I knew them all :) I'd always assumed expressions would be evaluated left to right. Might explain some weird bugs I have had.]]> bobc Controllers Sun, 16 Feb 2014 09:32:54 -0500 https://reprap.org/forum/read.php?13,311417,311550#msg-311550 https://reprap.org/forum/read.php?13,311417,311550#msg-311550 github.com]

the above implies there was an issue with larger rom back 2010, but was fixed.

Uew this latest version, apparently the one with ardueno prier to v1 is quite old.]]> Dust Controllers Sun, 16 Feb 2014 06:32:22 -0500 https://reprap.org/forum/read.php?13,311417,311537#msg-311537 https://reprap.org/forum/read.php?13,311417,311537#msg-311537 heliosoph.mit-links.info]

Memory size of the target should not be a problem.]]> bobc Controllers Sun, 16 Feb 2014 06:17:02 -0500 https://reprap.org/forum/read.php?13,311417,311488#msg-311488 https://reprap.org/forum/read.php?13,311417,311488#msg-311488
Yes you can set the fuses without uploading a new bootloader. Just use the command line tool avrdude

Cant help with the rest, I use a real programmer :)]]> Dust Controllers Sun, 16 Feb 2014 01:59:49 -0500 https://reprap.org/forum/read.php?13,311417,311417#msg-311417 https://reprap.org/forum/read.php?13,311417,311417#msg-311417
I have a Sanguinololu that uses the Atmega1284p, and am having some trouble with. The endstops will not register and the motors will only spin in one direction no matter what settings are changed in firmware(I'm using Marlin, btw). After some searching I believe the problem is that the JTAG fuse settings for the chip are wrong, and that it must be disabled. I never uploaded the bootloader myself, and bought it with it already installed, so I'm not *exactly* sure how to fix it. I don't want to buy an ISP programmer at all, and I know I could buy a new chip from a different seller that has been tested, but if can fix it for free while learning something new, I'm willing to try. Worse case scenario I brick the chip, and have to buy a new one anyway.

Can I use the Arduino Uno as an ISP programmer? I've seen various post that say you can and cannot. It's usually said that it has to be a pre- Arduino Uno, one that uses an FTDI chip. Also I believe there are memory limits that restrict what type of programmer can be used. If the UNO can be used as an ISP, can it handle the memory size of the 1284p?

I'm also under the impression that you can change the Fuse settings without burning an whole new bootloader? Is that true?

Thanks in advance.]]> theruss007 Controllers Sat, 15 Feb 2014 17:18:47 -0500