J721EXSOMXEVM: Unable to write to registers - MCU1_0 SBL

Arun Belamge

Part Number: J721EXSOMXEVM

Tool/software:

Hello Everyone.

I am booting the MCU Domain Cortex - R5F (mcu1_0) using the SBL in lockstep mode.

I have a baremetal code running on the R5F, but any register i try to write, I am unable to write. I can successfully read the register, but my writes to registers are failing.

Above snippet shows that I am trying to first read the CTRLMMR_GTC_CLKSEL register and then writing 0xF to this register.

But when i run the program, I can see that the register has not been written. I ve tried directly using the address and writing as well as using the "hw_types.h" API (HW_WR_REG32(addr, value)). But both fail to write to the register.

Please help.

4 months ago

0 Karthikeyan S 4 months ago

TI__Genius 13220 points

Hi Arun,

Arun Belamge said:
But when i run the program, I can see that the register has not been written. I ve tried directly using the address and writing as well as using the "hw_types.h" API (HW_WR_REG32(addr, value)). But both fail to write to the register.

Could you please share me the register Address?

Regards,

Karthik

0 Arun Belamge 4 months ago in reply to Karthikeyan S

Prodigy 110 points

Hi Karthikeyan.

Thanks for the response.

The register address is 0x00108030 (CTRLMMR_GTC_CLKSEL - 0010 8030h).

I ve even tried writing to the Counter value registers GTC_CNTCV_LO - 00A9 0008h and GTC_CNTCV_HI - 00A9 000Ch.

Still, I am not able to write to the registers. (read is happening)

Thank you.

0 Arun Belamge 3 months ago in reply to Arun Belamge

Prodigy 110 points

Hi Karthikeyan.

Any information on this?

And one more question.

The default value for this register, CTRL_MMR_GTC_CLKSEL, is 0, which corresponds to the clock signal MAIN_PLL3_HSDIV1_CLKOUT.

I am not able to figure out the frequency of this signal. Is it 200MHz or 250MHz or something else?

Thank you!

+1 Karthikeyan S 3 months ago in reply to Arun Belamge

TI__Genius 13220 points

Hi Arun,

The CTRL_MMR0 module has a protection mechanism which prevents spurious writes from changing the values
of its registers. there need to unlock the MMR register for write the CTRLMMR_GTC_CLKSEL register.

    printf("CTRL_MMR_UNLOCK \n");
        
     Board_init(BOARD_INIT_UNLOCK_MMR);            //  MMR Unlock
     
     HW_WR_REG32(0x00108030, 0x0F);
     
     Board_deinit(BOARD_DEINIT_LOCK_MMR);          //  MMR Lock
     
     printf("CTRL_MMR_GTC_CLK Write Complete\n");

Arun Belamge said:
I am not able to figure out the frequency of this signal. Is it 200MHz or 250MHz or something else?

Could you please refer the following documents.

file: <pdk>/packages/ti/drv/sciclient/soc/sysfw/binaries/system-firmware-public-documentation/5_soc_doc/j721e/pll_data.html

file: <pdk>/packages/ti/drv/sciclient/soc/sysfw/binaries/system-firmware-public-documentation/5_soc_doc/j721e/clocks.html

Regards,

Karthik

0 Arun Belamge 3 months ago in reply to Karthikeyan S

Prodigy 110 points

Hello Karthikeyan.

Thanks for the response.

And I can confirm it works, didn't know there was Write protection for the register. Is there any documentation which discusses the same?

Thank you!

Best regards

0 Arun Belamge 3 months ago in reply to Arun Belamge

Prodigy 110 points

Hi Karthikeyan.

Arun Belamge said:
The default value for this register, CTRL_MMR_GTC_CLKSEL, is 0, which corresponds to the clock signal MAIN_PLL3_HSDIV1_CLKOUT.

From the documentation you provided... I could find this,

So, MAIN_PLL3_HSDIV1_CLKOUT corresponds to,

MAIN3 - 2000000000U - HSDIV1 (8) == 250MHz. Is my understanding correct?

Thank you!

0 Karthikeyan S 3 months ago in reply to Arun Belamge

TI__Genius 13220 points

Hi Arun,

Arun Belamge said:
MAIN3 - 2000000000U - HSDIV1 (8) == 250MHz. Is my understanding correct?

Could you please refer the https://software-dl.ti.com/jacinto7/esd/processor-sdk-rtos-jacinto7/10_01_00_04/exports/docs/pdk_jacinto_10_01_00_25/docs/userguide/jacinto/faq/faq_module_clocking.html FAQ, it helps to know which module is running at what frequency.

Regards,

Karthik

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J721EXSOMXEVM: Unable to write to registers - MCU1_0 SBL