BOOT_CFG pin pull ups during reset

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BOOT_CFG pin pull ups during reset

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AlexHarford
Contributor II

The BOOT_CFG balls are listed as having pull ups, and I would like to know if these pull-ups are active during reset. This would let us save the routing to those balls if we want them to be set to 1, and aren't using them after reset. I could not find any details about this in the SRC, Fusemap, or System Boot chapters of the iMX6 Reference Manual.

This would be using Internal Boot Mode (BOOT_MODE[1:0] = 0b10).

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Yuri
NXP TechSupport
NXP TechSupport

Pull up / down options of i.MX6 pins are software configurable, therefore BOOT_CFG pins pulling during reset / power-up are not fully

defined. This means external resistors should be applied (except the case fuse-only boot configuration), as recommended in the Design Checklist :
"The BOOT_CFG signals are required for proper functionality and operation and should not be left floating."

"Each EIM boot signal should connect to a series resistor to isolate the bus from the resistors and/or switchers; [...].

Each configured EIM boot signal sees either a 14.7 kΩ pulldown or a 4.7 kΩ pullup. For each switch-enabled

pulled-up signal, the supply is presented with a 10 kΩ current load. "   

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MehmetAliIpin
Contributor V

Dear Yuri,

Hello,

if we want to use serial boot mode ("01"), in order to program the fuses with manufacturer tool kit (over USB) or JTAG tool software, do we still need to use all of these resistors?

Best regards

Mehmet Ali Ipin

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Yuri
NXP TechSupport
NXP TechSupport

For fuse only or serial boot modes there is no need for the resistors.

In the same time, SD Manufacture mode may influence here :

Re: i.MX6 solo: problem forcing it into USB serial downloader mode

~Yuri.

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