ATMEGA 1284 boot loader

Using Arduino Microcontrollers
#1

Hi,
I have a MEGA 1284 built onto a breadboard, after installing Optiboot I ran a blinky test sketch and all was fine. After a change to 3.3v operation and 12 MHz crystal ( was 16 MHz) I loaded a different version of optiboot, ran the blinky again and all was well.

I then tried connection a Wiz820IO module, there was no response. Checked it using a MEGA 328 and the wiznet module was fine. I then though I would go back to the original Optiboot and try that, but now I can't load any version of Optiboot at all.

Error returned is: avrdude protocol error expect 0x14, response 0x50
Using an arduino as ISP
Original Optiboot was from maniacbug
Second version of Optiboot homehack-max

Any help or suggestions would be apreachiated.

#2

Two possible suggestions. First, are you really sure you hacked the bootloader code correctly
for operation at 12 Mhz? That's a non-standard clock value, and all the timing and baudrate
settings will be very different. Might be easier to try 8 Mhz, as that's a standard, and
bootloaders are already available.

Secondly, the 328 and 1284(P) chips run perfectly well with 16 mhz xtal at 3.3V [despite
some dire warnings of imminent chaos and disruption on the horizon]. So, you might "try"
it that way [but always be careful to watch for chaos showing up]. If you look at the
datasheets carefully, and interpolate the graphs, you'll see they show clock = 13.3 Mhz
at 3.3V, so 16 Mhz is "only" 20% overclocking.

Also, note that you cannot burn the bootloader into a 1284 chip using the 1284P setting,
in case you really have a 1284 and not a 1284P chip.

#3

It is an ATMEGA1284P so that should not be an issue.

I downloaded both bootloaders, I am afraid hacking a bootloader is beyond my skill set. The main issue at the moment is that I can no longer get a bootloader to load. Could this be due to an issue with the bootloader that is currently installed, nd is there a way to reset the processor back to default?

#4

The maniacbug optiboot will burn fine into the 1284P, with 16 Mhz xtal.
Look at this tutorial,

#5

Hi, the maniacbug boot loader did load fine, then I changed it to the home hack-max boot loader. Now I can't get any boot loader to load at all.

#6

Are you trying to reburn the bootloader or burn a sketch into the chip?

If you can't reburn the bootloader using the ArduinoISP, then maybe you be a regular
ISP programmer to erase the chip completely, but I don't know anything about that.
??? [you need to find one of the big guns around here, ;-)].

#7

The 1284p (328p) works fine @16MHz and 3V3. Set full swing oscillator to be safe..
Atmel guarantees the parameters in -40..+85 degC region, therefore the official MHz rating for 3V3 is lower..

#8