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Topic: Regression between uno and uno R2 VALIDATED. HARDWARE PROBLEM CONFIRMED (Read 27 times) previous topic - next topic

westfw

optiboot (which has run on ALL the Uno boards) does not enable ANY interrupts.  At least not on purpose.
PD0/PD1 would be used explicitly if the bootload was compiled to use a software uart (not likely.)

foubarre

#11
Jun 21, 2011, 12:30 pm Last Edit: Jun 21, 2011, 12:32 pm by foubarre Reason: 1
Thanks for the answers. Hopefully, if standard peripherals sold by sparkfun don't work anymore, we can expect a fix rapidly.

As a note, i do not use the SMD version of uno. This, then, seems to indicate that at least it would not be due to a faulty CPU batch and that if there is a routing mistake, it has to be the same on both boards.

edit: By the way, it seems that pulling up non-PWM pins block the boot, while PWM pins don't. Any clue?

foubarre


If you take the AVR out of one of the new and misbehaving boards, and put it in a Rev1 board, does it start behaving?

I tried that. Swapping AVR from a R1 UNO to R2 UNO does not change behavior. It is not related to AVR, looks like the board itself is the culprit.

robert rozee

#13
Jun 21, 2011, 02:49 pm Last Edit: Jun 21, 2011, 02:51 pm by robert rozee Reason: 1

I tried that. Swapping AVR from a R1 UNO to R2 UNO does not change behavior. [...]


a little confused here - can you just clarify: if you swap the 328p chips over, the R1 works (is not disrupted by a pullup on D7) while the R2 stops working with the pullup present?

this might suggest a problem in the area of the USB controller the UNO uses, where the presence of the pullup affects how the bootloader responds to incoming serial traffic from the 8U2. but this still depends on the bootloader "caring" that a pullup is present.

another thing to check on - is the 328p getting good power? that is a solid 5v, preferably monitored with a scope for any spikes. remembering that the power comes via a FET that is wired up in an arrangement that has been questioned in the past.

foubarre

Sorry for confusion.

Quote
a little confused here - can you just clarify: if you swap the 328p chips over, the R1 works (is not disrupted by a pullup on D7) while the R2 stops working with the pullup present?

TRUE.
And i should add "R1 still works while R2 still does not"

Quote
is the 328p getting good power? that is a solid 5v, preferably monitored with a scope for any spikes. remembering that the power comes via a FET that is wired up in an arrangement that has been questioned in the past.

It fails the same way using the USB power or external power.
As USB is done to only use power once alimentation stabilized, it should be fine. Not tested, though.

AFAIU, FET is not implied when board is powered through usb, right?

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