Tool/software:
Hi Experts,
Customer did not implement power switch and the reset logic for supporting UHS-I SD card.
So customer cannot provide a low to high to the GPIO11 to enable SD card supply.
In case customer does no use UHS-I speed and the POWER switch to control the SD card supply and the power switch EN logic is not implemented, is there a recommendation to connect GPIO11.
Currently the GPIO11 is left open and the LDO output is not available.
Regards,
Sreenivasa
Hello Kallikuppa,
In case customer does no use UHS-I speed and the POWER switch to control the SD card supply and the power switch EN logic is not implemented, is there a recommendation to connect GPIO11.
In short, the recommendation is to ground GPIO11, now GPIO11 is tied to enabling LDO1.
Setting on the TPS65931211 for GPIO11:
As for the output settings for LDO1:
BR,
Nicholas McNamara
Hello Kallikuppa,
For the customer, depending on what software they're using they can just connect it to one of the GPIOs on the AM62A and toggle it that way.
As for enabling LDO1, it can be turn on via software writes. Now it should be mentioned that with the 5V0 input of VCCA the following should be adhered to since LDO1 is by default a load switch for 3V3. If it does not see the 3V3 on the input when enabled it will flag and interrupt and attempt to restart. This configuration for bypass vs linear regulator mode can be changed via softwarewrites
The question on the recommendation for the GPIO11, please have this answered by the Sitara team as their recommendation as per their software package.
BR,
Nicholas McNamara
Kallikuppa,
Thank you for the context, this actually helps explain the problem and why you need all of the other details.
So unfortunately, it's not until the PORz (PMIC's nRSTOUT pin) goes high will the PMIC react to the anything on GPIO11 (SD_CARD enable, LDO1 on PMIC) as seen below on the diagram.
If the customer had to make a "blue wire" connect for GPIO11, it have to be a signal after the PORz goes high on the system. So it can not be tied to the VCC_3V3_MAIN as the GPIO11 reacts to a rise condition on the pin.
Okay so no special software considerations if there was software to turn on LDO1, but the issue now is that there needs to be a hardware signal to GPIO11 after the PORz goes high. Suggestion of a domain that goes high after the PORz is asserted.
BR,
Nicholas McNamara
Hello Kallikuppa,
If i can summarize the inputs, the only wany to enable the LDO1 is for the input to GPIO11 go from low to high after the nRSTOUT pin goes high.
That is correct.
I suspect there is no concern in terms of input slew in case any of the switched 3.3V supply is connected.
There are limitations on the pins as from the line items above, just for awareness, but rarely would this ever get violated. These line items imply that the VIO_IN should NOT ramp up before the VCCA/PVIN pins, other than that no concerns from the PMIC side.
BR,
Nicholas McNamara
