AM5746: Initial setting of SDVS on MMCHS_HCTL register in the MMCSD driver

Hideaki Matsumoto

Part Number: AM5746

Hi,

The customer has a question about the MMCSD driver below.

In the MMCSD_v1.c, SDVS [bit 11:9] in the MMCHS_HCTL register is started from setting 0x6 (3.0V), but it’s started from 0x7 (3.3V) in the MMCSD_v2.c.

What does this difference impact ? What does this change mean ?

Used SD card : UHS support SD card (Speed class I)

Device : AM5746

Dev Environment : CCS v8

Compiler : GCC GNU v6.3.1 (Linaro)

Hardware : AM5746 customer’s own board

Software : pdk_am57xx_1_0_11

OS : Bios_6_76_00_08

XDCTools : 3.50.3.33

ICE : Lauterbach

Regards,

Hideaki

over 2 years ago

0 jian35385 over 2 years ago

TI__Mastermind 23125 points

Hideaki,

I would expect we set for 3.3v for the AM57 driver (_v1) also. It might worked as actual IOs are all 3.3v nominal. I will check with the hardware team if there were specific reasons we set it at 3.0v.

regards

Jian

0 jian35385 over 2 years ago in reply to jian35385

TI__Mastermind 23125 points

Hideaki,

I installed the latest RTOS SDK for AM57, and noticed in PDK 1_0_18 (RTOS SDK v6.03..2.8), the initial voltage was set at 1.8v.

./mmcsd/src/v1/MMCSD_v1.c: HSMMCSDSetBusVolt(hwAttrs->baseAddr, CSL_MMCHS_HCTL_SDVS__1V8);

So assuming your hardware have 3.3v for initial SD card voltage, you should set to 3.3 for initial commands, then switch to 1.8v for higher speed. Of course, if you are using 1.8v eMMC devices, then you should set IO voltage at 1.8v fixed.

regards

Jian

+1 jian35385 over 2 years ago in reply to jian35385

TI__Mastermind 23125 points

Hideaki,

Also I received a note from our team that the 3.0v voltage setting was due a TRM typo and later fixed.

Jian

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AM5746: Initial setting of SDVS on MMCHS_HCTL register in the MMCSD driver