[MinnowBoard] Problem booting with activity on I2S_FRM

Anders, David david.anders at intel.com
Sat Mar 28 00:04:22 UTC 2015


Darren is correct that this is a boot strap pin, and I'd recommend using a different one if you are using it directly as a GPIO on startup, or else take care that it is not pulled low on reset...

Dave Anders

-----Original Message-----
From: elinux-MinnowBoard [mailto:elinux-minnowboard-bounces at lists.elinux.org] On Behalf Of Darren Hart
Sent: Friday, March 27, 2015 6:45 PM
To: MinnowBoard Development and Community Discussion
Subject: Re: [MinnowBoard] Problem booting with activity on I2S_FRM

On 3/27/15 2:24 PM, Lucas De Marchi wrote:
> Hey,
> I'm using the pin GPIO_I2S_FRM for gpio in my application. However 
> when I boot the board, if there's any activity on this pin already, 
> the board doens't boot. I get nothing on serial, not even the messages 
> from the bios. As far as I tested this is the only pin that exhibits 
> this behavior.
> Firmware version is 0.78.  Is there anything that can be done to boot 
> the board even with activity on this pin?

Thank you for reporting this Lucas. I've looked into the design documents and that pin is also a strapping line which happens to select the BIOS boot:


While there is a buffer/voltage-shifter between the LSE connector and the SoC, it is possible that a low signal to the LSE connector is causing the SoC side of the signal to be pulled low, overpowering the 10k strap pull-up, effectively telling the SoC to boot via LPC instead of SPI, causing the issue you describe.

Can you describe exactly what activity you have applied to this pin at boot?

Darren Hart
Intel Open Source Technology Center
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