Problem with start of board with AT91SAM9x5

Discussion around AT91RM9200 and SAM9 Series Products.

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Emco
Posts: 10
Joined: Wed Aug 02, 2017 11:16 am

Problem with start of board with AT91SAM9x5

Fri Jun 22, 2018 1:45 pm

Hello,
I have problem with start of board with AT91SAM9x25.

Board:
- MCU AT91SAM9x25
- 4.4.26-linux4sam_5.5
- buildroot 2016.11.2

If I do not use battery for RTC (VDDBU) all works fine.
But if I use battery for RTC (VDDBU), so several times start (several times power ON, power OFF, power ON, power OFF,...) is OK and then board don't start, and NRST pin is still in log. 0. After power OFF and power ON, board still don't work (NRST pin is still in log. 0). I must remove battery and insert battery and then board again works fine (NRST pin is still in log. 1).
I use 1K5 pullup resistor on NRST pin.

Thank you in advance

Regards
Emco
blue_z
Location: USA
Posts: 1716
Joined: Thu Apr 19, 2007 10:15 pm

Re: Problem with start of board with AT91SAM9x5

Mon Jun 25, 2018 1:04 am

Emco wrote:But if I use battery ... then board don't start,
You neglect to mention how closely your board adheres to the Atmel reference design, but I can get an Atmel SAM9X35-EK to power-up into a limbo state (indicated by absence of "RomBOOT" text on DBGU port ) quite easily (e.g. after one or two power cycles).
My testing of the EK board indicates that the power-up issue requires an installed battery and that the SoC is most vulnerable during the transition phase starting when AT91Bootstrap has loaded the U-Boot image and ending when U-Boot displays its version message.
If code is executing outside of this transition, then the power cycle is typically okay.
Issue seems distinct from the "Reset during SDRAM Accesses" Errata.

I'm not a circuit/board designer, so the only advice I have is try Microchip technical support or the other Atmel/Microchip site where there's more HW folks.


Emco wrote:- MCU AT91SAM9x25
That's a MPU.
Emco wrote:... NRST pin is still in log. 0.
Concocting your own abbreviation?
Don't, it's confusing like bad grammar.

Regards
Emco
Posts: 10
Joined: Wed Aug 02, 2017 11:16 am

Re: Problem with start of board with AT91SAM9x5

Mon Jun 25, 2018 2:22 pm

I'm sorry for my english.
My problem is "Reset Controller (RSTC)".
How can I disable (or set, or reset) this "Reset Controller (RSTC)"?
Is it possible change in file at91sam9x5.dtsi ?
In this file is define:

Code: Select all

rstc@fffffd00 {
				compatible = "atmel,at91sam9g45-rstc";
				reg = <0xfffffd00 0x10>;
			};

Thank you very much

Regards
Emco
blue_z
Location: USA
Posts: 1716
Joined: Thu Apr 19, 2007 10:15 pm

Re: Problem with start of board with AT91SAM9x5

Tue Jun 26, 2018 1:04 am

Emco wrote:My problem is "Reset Controller (RSTC)".
Maybe. Maybe not.
How do you know it's not the Slow Clock Controller?
You're just guessing.

Emco wrote:How can I disable (or set, or reset) this "Reset Controller (RSTC)"?
You can't. The RSTC doesn't even have a peripheral ID number.

Regards

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