AM625: AM6254: MMC SDIO drive strength and PMT mode

Hello Anil Patel, 

Thank you for the query.

Let me check internally and update you. Please expect a delayed response due to US holiday.

Regards,

Sreenivasa

Sure. Thank you.

Hello Anil Patel, 

Noted.

Regards,

Sreenivasa

Hello Anil Patel, 

We want to know that, can we configure MMC SDIO pins drive strength in software on the platform side? Or do we need to control it through hardware only?

Could you please help us understand the use case to increase the drive strength.

Regards,

Sreenivasa

Hello Anil Patel, 

In addition to that, can you please explain what is PMT mode in AM6254?

The PMT mode is not recommended for external use and please ignore the PMT mode. 

Regards,

Sreenivasa

Hello Sreenivasa,

We are developing a custom board just like EVM.

We want to know that do we control drive strength through software or not? If we can control then there is no need for any extra hardware peripherals.

Otherwise, we need to provide provisions for extra registers for drive strength control through hardware.

Hope that answers your questions.

Thanks,

Anil Patel

Understood.

Can you just explain to me what is PMT mode?

What does it stand for?

Regards,

Anil

Hi Sreenivasa,

What is drive current fixed internally for all MMC I/Os? Does it needed to keep series resistor to control slew rate of signals for EMI ?

Hi Sreenivasa,

Thanks for info.

How about other interface like, OSPI, SPI, GPMC, I2C, GPIOs? Do they have drive strength control? 

If yes, Advise drive current range and configuration documents.

If no, Do you recommend series resistor on all output drive signals?

Hello Kalpesh, 

Thank you for the query.

Based on my understanding, the drive strength is not available for the peripherals you listed.

Can you pls hep me understand the use case for programmable drive strength. 

Adding series resistor is a good practice but that should also be followed up with simulations.

Regards,

Sreenivasa

Hi Sreenivasa,

Thanks.

Use for programmable drive strength is to control slew rate of signals to improve signal integrity and to control EMI if needed.

We generally doing this control with adjusting the series resistor value in range of 10R to 47R but this will not needed if drive control is there inside the soc. We can achieve the similar thing with reducing the drive control.

Thanks Sreenivasa.