Question, i.MX6SX IO Voltage change

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Question, i.MX6SX IO Voltage change

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SLICE
Contributor IV

Hello team,

My customer is trying to switch IO voltage of eMMC from 3.3V to 1.8V.

And they have changed LVE bit in following registers into 1 (this operations were done from u-boot prompt), but they cannot saw the IO voltage got to change.

 

MX6_PAD_SD3_CLK__USDHC3_CLK

MX6_PAD_SD3_CMD__USDHC3_CMD

MX6_PAD_SD3_DATA0__USDHC3_DATA0

MX6_PAD_SD3_DATA1__USDHC3_DATA1

MX6_PAD_SD3_DATA2__USDHC3_DATA2

MX6_PAD_SD3_DATA3__USDHC3_DATA3

MX6_PAD_SD3_DATA4__USDHC3_DATA4

MX6_PAD_SD3_DATA5__USDHC3_DATA5

MX6_PAD_SD3_DATA6__USDHC3_DATA6

MX6_PAD_SD3_DATA7__USDHC3_DATA7

 

Could you show me how to change the IO voltage of eMMC I/F?

 

They tried the way described in the following thread, but they saw there is no change in the IO voltage.

https://community.nxp.com/message/597607

 

Please show me the way to change the IO voltage of eMMC I/F of i.MX6SoloX.

Thanks,

Miyamoto

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7 Replies

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igorpadykov
NXP Employee
NXP Employee

Hi Miyamoto

as stated on that link customer succeeded with jtag settings, while

operations from u-boot prompt were not reliable. So one can attach jtag and

write LVE bit with jtag. Also check NVCC_HIGH which is 3.3 V supply input for the

dual-voltage I/Os on the SD3 interface, NVCC_LOW - 1.8 V supply input for the

dual-voltage IOs on the SD3 interface as described in Table 109. 19x19 mm Supplies

Contact Assignments i.MX6SX Datasheet
https://www.nxp.com/docs/en/data-sheet/IMX6SXCEC.pdf

Best regards
igor
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550 Views
SLICE
Contributor IV

Hi igorpadykov

Thanks for your support.

The customer is still trying to connect with JTAG, but it does not work yet.

What the customer wants to achieve is to use eMMC I/F of i.MX6SX with 1.8V.

They do not want to change the voltage dynamically.

Now the voltage level is 3.3V on their board, and they believe changing LVE bit can change the physical voltage level of eMMC to 1.8V. 

If any other procedure needed to achieve their requirement, please let me know.

Thanks,

Miyamoto

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igorpadykov
NXP Employee
NXP Employee

Hi Miyamoto

I am afraid such procedure is not available. One can use

linux, it changes voltage automatically if eMMC supports modes

which require 1.8V switching.

Best regards
igor

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550 Views
SLICE
Contributor IV

Hi igorpadykov

Thanks for your support.

Can I understand that your current LinuxBSP contains automatic voltage switching feature if LVE bits are correctly set-ped?

BR,

Miyamoto

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igorpadykov
NXP Employee
NXP Employee

Hi Miyamoto

 

yes linux changes voltage automatically, one can look in mmc driver
 linux/drivers/mmc/host/sdhci-esdhc-imx.c, function sdhci_esdhc_imx_probe_dt

Best regards
igor

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550 Views
SLICE
Contributor IV

HI igorpadykov

Actually, the customer uses Linux for their board, and its versions are as below.

- U-Boot 2015.04-imx_v2015.04_4.1.15_1.0.0_ga+gd7d7c43

- Linux imx6sxsabresd 4.1.15-1.1.1+gd5d7c02

Does it contain the 'automatic voltage switching' feature?

BR,

Miyamoto

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igorpadykov
NXP Employee
NXP Employee

Hi Miyamoto

 

yes nxp linux bsps described below, change voltage automatically

Best regards
igor

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