i.MX RT1020 Arm core frequency

[arnaud2gerard_f]

Hello,

I have some questions on the Core frequency of the different versions of RT102x

i.MX RT1020 Crossover Processors for Consumer Products, Rev. 1, 04/2019 Page 7

There are different frequencies from 400MHz to 1000MHz.

I would like to know what the default frequencies are because Processor Reference manual and NXP website always specify a core frequency of 500MHz.

1. I have a custom board with MIMXRT1021CAG4A thus a core frequency of 400MHz: is this the default frequency? the maximum frequency?

2. Do I have to modify the core frequency at startup?

3. Can I keep the default frequency of 500MHz?

4. I set the clocks sel and clock podf and evk and custom board works at 400Mhz. Great. But code of the second bootloader (AN12604
Implement second bootloader on i.MXRT10xx series) do not modify the frequency. Is this a bug? a missing feature of the code?

5. I tried to set up  a DCD table to have the equivalent but some registers are not accessible (e.g. XTALOSC24M_LOWPWR_CTRL).

The configuration I need for the custom board (SRAM, SDRAM, LPUART, FLEXSPI, LPSPI requires some special frequencies and this constrain the clocks selection and dividers) is not possible with DCD table. Please, note that the configuration is working well with a connection script (.scp)

Thanks for you answers,

Regards.

[FelipeGarcia]

Hi,

I think this is a misunderstanding. The different frequencies listed in page 7 refers to all the RT families available not only RT1020 and it is just to demonstrate the part number nomenclature. To see what are the frequencies depending on the part number you need to check section 1.2 Ordering information. As you can see there is only 500 MHz (Max frequency) device.

To modify the core frequency I recommend you to use MCUXpresso Config Tools as it is easy to use. You can learn more about the registers used to configure clocks in clock_config.c file in our MCUXpresso SDK examples.

Best regards,

Felipe

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[arnaud2gerard_f]

Thanks for your answer Felipe.

- Yes, there is a misunderstanding: I thought that the frequency was set to 500MHz when the processor is powered on. Thanks to the clock tool of the IDE, I realized I was wrong: the default cor frequency is 24MHz ("BYPASS" names are weird)

- That's why I need to modify it to 400MHz. I thought it was possible with the DCD table, but some registers cannot be modified: I need to modify them with a program loaded in the OCRAM (SPL) because it is needed (for my application) to separate the clock path of the FlexSPI from the SEMC clock and to modify them separately.

- I was referring to the wrong datasheet in my initial post. This should be i.MX RT1020 Crossover MCUs for Industrial Products

Thanks and regards