AM623: How to set SDIO Clock/Data samping?

Hello Gibbs,

You may get a delayed reply as today is a holiday in Dallas.

Regards,

S.Anil.

The MMCSD module is able to support the timing modes defined in the respective MMCSD timing section of the datasheet. The software driver will determine what is supported by the attached device and configure the peripheral to achieve the best throughput. I'm not able to answer software questions but can assign this thread to someone from our software team if you have additional questions about configuring the software driver to use a specific timing mode.

Regards,
Paul

Hi, Peaves

Thanks your replies, pls help me forwarding this problems to SW team.

I want to know how to adjust timing on SW.

Thanks

Gibbs

HI Gibbs,

What software do you use on AM623? Linux?

Hi, Bin

They use Linux. but I think you can

1. Provide us Linux DTS setting , or

2. Tell us how to setting related register

Thanks

Gibbs

Hi, Bin

I feel a little bit confuse.

Our question is "How to set SDIO Clock/Data samping? "

For example, capture data on clock raising edge or fall edge ...

I think DT property "max-frequency" just adjust MDIO clock speed, isn't?

https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/sdhci-st.txt

Thanks

Gibbs 

Why are you trying to select a specific data transfer mode rather than allowing the software driver to select the most appropriate mode supported by the attached SD Card?

Note: you may need to limit the modes software can use based on your PCB design. For example, you may need to restrict software to only use up to the fastest 3.3V mode if you do not provide an IO power supply that is able to change the IO voltage from 3.3V to 1.8V when using a UHS-I card that initially operates with 3.3V signaling and later changes to operate with 1.8V signaling. Even with this example, you do not specify a specific mode of operation. You simply define the max mode supported by your hardware implementation.

Hi, Peaves

Sorry, let's me explain more detail.

Customer use AM62x SDIO to connect WiFi module (CC3300), NOT eMMC device.

Question 1 : 

They try to capture signal as below.

blue line --> clock, green line -->data

Data line "change state" when clock on "rasing edge",  Is it a normal SDIO chart? (y/n)

Compare to data sheet, I feel a little bit confuse.

Question 2 : 

As far as I know, "standard" sdio interface capture data on raising edge, so capture data on falling edge is unusual requirements? (y/n)

Question 3 :

Does AM623x support connect to CC3300? (y/n)

I think the answer should be yes, because I think CC3300 also raising edge capture by default.

Ref page 15

https://www.ti.com/lit/ds/symlink/cc3300.pdf?ts=1705556819644&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FCC3300%253FkeyMatch%253DCC3300%2526tisearch%253Dsearch-everything%2526usecase%253DGPN-ALT

Many Thanks

Gibbs

Hi Gibbs,

I will leave the first two questions to Peaves, but for questions 3, yes I think CC3300 can be connected to AM62x devices. There are several reference designs with AM62x and CC33xx.

Thanks peaves and BIN, your explanation is very clear