Trouble with fuse settings for atmega1284p-au

Other Hardware 3rd Party Boards
1

I having problems with choosing the correct fuse settings for a 1284P-au. I have tried using an avrisp MK11 with atmel studio 7, ardiuno as isp, and Nick Gammon's Atmega_Board_Programmer. So far it appears, I have bricked 4 uc's. Anybody know of a way to recover a chip after the fuse settings make it unrecognizable?
Here's settings i have tried which were taken from boards.txt:

#make atmega1284 AVR_FREQ=16000000L BAUD_RATE=115200 UART=0 LED=B0 LED_START_FLASHES=2
1284.menu.clock.16MHz_external=16MHz external (BOD 2.7v)
1284.menu.clock.16MHz_external.upload.speed=115200
1284.menu.clock.16MHz_external.bootloader.low_fuses=0xff
1284.menu.clock.16MHz_external.bootloader.high_fuses=0xde
1284.menu.clock.16MHz_external.bootloader.extended_fuses=0xfd
1284.menu.clock.16MHz_external.bootloader.file=optiboot/atmega1284/optiboot_atmega1284p_16MHz_external.hex
1284.menu.clock.16MHz_external.build.f_cpu=16000000L

What is really frustrating is that I have used the same settings to successfully flash the 40pin DIP package, no problems.

2

Try full swing crystal oscillator clock setttings:
Full Swing Crystal Oscillator 0111 - 0110
I use f7 in Low Fuse byte for that.
1284.menu.clock.16MHz_external.bootloader.low_fuses=0xf7

3

Assuming it's bricked because you've told them to use an external oscillator that is not present or functioning, or an external crystal that isn't present or functioning (as Crossroads noted, the 1284p doesn't seem to work reliably if crystal isn't set to full swing)...

Unbrick the microcontrollers by supplying an 8 or 16mhz square wave to XTAL1 pin and write the correct fuses. There's a version of arduinoasisp that outputs an 8mhz clock for this purpose.

4

I have attached pictures of the board with a 16Mhz Crystal; decoupling caps are on the bottom side. So you're suggesting that crystal isn't functioning properly. ill swap it out and see if that makes a difference. otherwise Ill have to wait until more IC's arrive :confused:

20151229_145333_resized_1.jpg
20151229_145333_resized_1.jpg1632×918 472 KB

20151229_144953_resized_3.jpg
20151229_144953_resized_3.jpg459×816 182 KB

5

It may not be functioning properly because you have the fuse set for low power crystal instead of full swing crystal, as crossroads noted above. From other posts I've seen, it sounds like lots of people have problems using fuses set for low power crystal, and that changing fuses to full swing crystal fixed it.

6

DOHHH! I had the crystal oriented wrong! I rotated it 90 degrees and everything is peachy, Thanks

7

Nice to hear you got it working.
I can see you're using an old version of the MightyCore. A lot have happens since then when it comes to bug fixes. Get the latest version at GitHub - MCUdude/MightyCore: Arduino hardware package for ATmega1284, ATmega644, ATmega324, ATmega324PB, ATmega164, ATmega32, ATmega16 and ATmega8535 . The full swing oscillator bits are enabled by default, making the microcontroller less sensitive :slight_smile:

8

What is the deal with that 4-leg crystal? Is that called an active crystal? I know about the 2-leg variety and the resonators with 3 legs and built-in caps, but don't know about when or where those 4-leg ones are used.

9

http://www.electroons.com/blog/2013/03/crystal-resonator-oscillator-difference/

In Other words, Oscillators are stand alone Clock Generating circuits while Quartz Crystal or Ceramic Resonators are just one part of the whole Oscillator Design. Quartz Crystal or Ceramic Resonator makes an Clock Oscillator when a feedback mechanism is incorporated with them. Like as shown in the Figure above where the feedback circuitry is actually exists inside the MCU itself. This kind of feedback circuit is necessary to achieve sustained oscillations.

A Clock Oscillator (One with 4 leg metal casing) has a Quartz Crystal as oscillating element and Feedback mechanism and Capacitors for sustained oscillations inside it, which makes it a stand alone clock generator.

10

Thanks. Looking at that article about the clock oscillator it appears you don't need to connect both XTAL1 and XTAL2, but in the photo seanz2003 attached it appears they are both connected anyway. I wonder about that.

11

most of those 4 pin smd parts are simple quartz crystal, not oscillators. i use thousands in my day job and the extra 2 pins are either case or completely nc. its quite easy to tell which are which with a simple continuity check.

12

EF=FC is recommended if you are using the chip at 5V. FD would set brown out detection at 2.7V.