topic Re: i.MX 8M Mini Configuration Resistor Strength in i.MX Processors

i.MX 8M Mini Configuration Resistor Strength

adevries — Fri, 27 Sep 2019 19:56:29 GMT

Hello Community,

For boot mode configuration pins on the 8M Mini like BOOT_MODE0, BOOT_MODE1, TEST_MODE, and JTAG_MOD, does it matter if I connect a very strong pull-up or pull-down resistor to these pins? Can I connect these pins directly to NVCC_JTAG or GND?

I believe these pins are always inputs, so I think it's acceptable to tie them directly to a power rail, but I want to ask and verify this before I accidentally blow up my 8M Mini.

Thanks

Re: i.MX 8M Mini Configuration Resistor Strength

AldoG — Tue, 01 Oct 2019 23:12:02 GMT

Hello,

Usually for pull-up resistors any value between 4.7k ~ 10k ohms, 4.7k ohm is preferred in high noise environments, for pull downs usually a 100k ohm is recommended.

Hope this helps,

Best regards,

Aldo.

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Re: i.MX 8M Mini Configuration Resistor Strength

adevries — Tue, 01 Oct 2019 23:29:15 GMT

Hi Aldo,

Thanks for the response. I know that the recommendation is for a 4.7-10k pull up and 100k pull down resistor. However, in my application, I'm looking to temporarily override some pull-up and pull-down resistors. For example, if I have BOOT_MODE1 set to 1 by pulling it high with 4.7k ohms, and I need to set BOOT_MODE1 to 0 temporarily, can I just ground the pin?

What if BOOT_MODE0 was set to 0 by pulling it low with 100k ohms, and I need to set it to 1. Can I connect the pin to NVCC_JTAG?

Thanks

Re: i.MX 8M Mini Configuration Resistor Strength

AldoG — Thu, 03 Oct 2019 21:39:36 GMT

Hello,

For this case scenario we suggest to place a switch, just like in our EVK, if you plan to change the logic state of the BOOT_MODE.

Also, the connection you mentioned shouldn't be done, you can use one of these two options for the BOOT_MODE pins:

Pulled up or down using the resistor I previously mentioned
Connected directly to NVCC_JTAG or GND

Pull-up regulate the amount of current it drives to the pin, if the power is not an issue it can be tied directly to VDD.

Hope this helps,

Best regards,

Aldo.

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Re: i.MX 8M Mini Configuration Resistor Strength

adevries — Fri, 04 Oct 2019 18:29:44 GMT

Thanks Aldo, that's good to know!