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Why i.MX6 doesn't resets after POR_B?

Question asked by Ingo Mersch on Jan 6, 2015
Latest reply on May 17, 2017 by jsmith883

Hello everyone.

 

I have a custom board based on i.MX6 ( Quad core version) and with linux running on it.

The board is bootingU-Boot from SPI. And then boots Linux from Network, SD-Card or CFast (on SATA). All works fine.

 

The configuration is done via GPIO overrides (BOOTMODE '10', "internal Boot"). The Fuses are not set.

 

I have an external reset-button which controlles the POR_B pin via a FPGA open drain output. The PF0100 also can generate a reset on POR_B pin with his open drain output RESETBMCU.

 

Now I have discovered that a reset propagated via FPGA doesn't work. The POR_B behaviour looks fine. So I had a deeper look into this issue.

 

What I discovered:  The i.IMX6 seems to ignore the GPIO overrides (or wrong read) and is falling back to serialdownload mode

                             If USB cable with Manufacturing Tool is connected (SPI flash is empty), the i.MX6 resets correctly and is booting in serial download mode.

 

May I solve this issue with burning the FUSEs? Or do I have to solve this issue like it is done in i.MX6 POR_B pin behaviour by also resetting the PF0100?

 

KR

Ingo

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