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Topic: Yay, got my new 1284 pcbs (Read 987 times) previous topic - next topic

tack

Pretty rich advice from Atmel considering where they put the Xtal pins!!

Surely a better design would have been between nice solid DC lines, where capacitive coupling would be virtually eliminated (possibly a very tiny amount due to ripple or noise on the DC lines). Maybe between Vcc and Gnd, or less frequently switched input like Reset and Gnd?

Siting the low impedance Xtal pin right next to RX0 on the 1284 wasn't very bright was it?

;-)

oric_dan

Quote
Siting the low impedance Xtal pin right next to RX0 on the 1284 wasn't very bright was it?

That's about what we're all thinking too.

I've been continuing to test my new pcb layout. So far, no problems using the atmega1284P
chips with data code 1247 - apparently very recent batch. I do have guard rings around the
xtal and RX0 pins. Am now also running the 1284P at 3.3V with 16-Mhz xtal now [against
all warnings, BTW], and not seen any problems uploading my large 86 KByte sketch.
So, either I have a good pcb layout, or else the latest chips are less prone to glitching.

Coding Badly

So, either I have a good pcb layout, or else the latest chips are less prone to glitching.


Those two are not mutually exclusive.   ;)

oric_dan

Guess it should say "and/or else", LOL.

tack

Well, I've not taken any special precautions on my first version prototype PCB layout, so when they arrive I'll check them with both fuse settings and the exact same 1284P I currently have sitting on a breadboard.

I know this chip wouldn't upload via serial until I either added the 10k series resistor in RX0 or altered the fuse settings. If I repeat that on the PCB then it will also show if the problem manifests more profoundly when on a breadboard.

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