EIM Signals and Boot Configuration

[durmus]

Hi all,

In our design based on SABRE SDP, we try to implement 3 configurations for boot selection:

• eMMC via USDHC3
• external SD/MMC card via USDHC1
• SPI NOR flash via ECSPI1

Out of 32 EIM signals related with boot configuration, we are using only 2 in our design, specifically EIM_EB2 (E22) as SPI1_CS0 and EIM_EB3 (F23) as UART1_RI_B.

I already removed the series bus isolation resistors (4.7k) because they are not connected to anywhere, except for those two above. I have 2 questions to make sure what I did is correct:

I checked the reference manual for the related signals for boot selections. When I guarantee that the boot-up process will occur either from USDHC1, USDHC3 or ECSPI1;

1) Do I have to connect other unrelated boot signals to ground via 10k resistors? Or can I connect them directly to ground?

2) Since EIM_EB2 and EIM_EB3 are irrelevant for the mentioned boot selections, do I need any isolation or pull-down for them? (since I'm using them as low active signals, it would not be correct to pull them down)

Thanks in advance.

Durmus

[igorpadykov · Accepted solution]

Hi Durmuş

1. one can connect them directly to ground

2. if these signals are used as outputs, they can not be grounded.

    They can be pull-ed with resistor. You may wish to look at

    sect.4.6.2 "General Purpose I/O (GPIO) DC Parameters" IMX6DQCEC

Best regards

chip

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