AM3352: Flouting period for GPIO2_25 (LCD_AC_BIAS_EN) at power up

Are they observing a mid supply on this pin?  Or they are just suspecting that it is floating?  LCD_AC_BIAS_EN is pulled low after reset, so unless they have a pull-up on the board, it probably stays low until used as a GPIO.  

We don't spec a maximum time, only recommendation is that the time at mid-supply should be minimized.  

Regards,

James

Hi James

When they put external pull-up, the floating period is about 25ms.

When they removed external pull, the floating period is about 30ms.

The following light blue signal is what we discuss now.

According to their waveform, I guess that

(1) SoC reset:  GPIO2_25 is LOW

(2) SoC reset release: GPIO2_25 is floating

(3) SoC internal pull-down enable: GPIO2_25 is LOW

(4) Pin mux set: GPIO2_25 is HIGH

Does it correct?

The external device which is connected to GPIO2_25 are affecting its behavior by this floating.

(The external device read the level of this signal, and behaves something.)

Therefore, customer would like to control the latching timing by this external device.

Then, they are asking the maximum  floating period of the pin.

Rough value is ok for them (e.g. 40ms, 50ms, and so on)

Could you give me your advice?

Thanks and Best regards,

Tsurumoto.

Tsurumoto-san, i don't have any spec for this.  And i'm not sure you sequence is correct.  There might be a more optimized GPIO that they could have possibly chosen.  What exactly is the circuit connected to this pin (ie, pulls resistors, devices, etc.)?

Regards,

james